Showing papers in "Bioprocess and Biosystems Engineering in 2019"
TL;DR: The synthesized silver and gold nanoparticles had a momentous anticancer effect against lung carcinoma cell line A549 in a dose-dependent manner and showed high antioxidant potentials, and were observed to be good catalysts for the reduction of organic dyes.
Abstract: The synthesis of metal nanoparticles by green methods attained enormous attention in recent years due to its easiness, non-toxicity, and eco-friendly nature. In the present study, noble metal nanoparticles such as silver and gold were prepared using an aqueous leaf extract of a medicinal plant, Bauhinia purpurea. The leaf extract performed as both reducing and stabilizing agents for the development of nanoparticles. The formations of silver and gold nanoparticles were confirmed by observing the surface plasmon resonance peaks at 430 nm and 560 nm, respectively, in UV–Vis absorption spectrum. Various properties of nanoparticles were demonstrated using the characterization techniques such as FTIR, XRD, TEM, and EDX. The synthesized silver and gold nanoparticles had a momentous anticancer effect against lung carcinoma cell line A549 in a dose-dependent manner with IC50 values of 27.97 µg/mL and 36.39 µg/mL, respectively. The antimicrobial studies of synthesized nanoparticles were carried out by agar well diffusion method against six microbial strains. Silver and gold nanoparticles were also showed high antioxidant potentials with IC50 values of 42.37 µg/mL and 27.21 µg/mL, respectively; it was measured using DPPH assay. Additionally, the nanoparticles were observed to be good catalysts for the reduction of organic dyes.
79 citations
TL;DR: The present study is the first effort done to synthesize of Cu-NPs from the extract of M. pinnata flower to establish the antioxidant, antibacterial, an anti-diabetic and anti-inflammatory agent, in vivo studies are made in the molecular level.
Abstract: The phenomenal and astonishing properties and their different application in the field of pharmaceutical made copper nanoparticles (Cu-NPs) to be in the spotlight of the researcher's focus. In the present study, copper nanoparticles were biologically synthesized with the aqueous extract of the flower Millettia pinnata, and their corresponding characteristics were studied using UV–visible spectroscopy, XRD, FT-IR, SEM, TEM, and SAED analysis. Copper acetate was reduced to copper nanoparticles and is confirmed by UV–visible spectrophotometer analysis. The maximum absorption occurring at 384 nm at the visible spectrum of UV rays confirms the surface plasmon resonance of the nanoparticles. The result of the FTIR spectroscopy analysis of the nanoparticles complements the involvement of organic mioties of the flower extract in the synthesis. The synthesized particles were extremely durable, spherical with the average particle size in the range of 23 ± 1.10 nm. The Cu-NPs exhibited greater inhibition on DPPH radical and nitric oxide scavenging activities. The biologically synthesized Cu-NPs was receptive to the Gram-negative and Gram-positive bacteria as well. The Cu-NPs exhibited strong anti-inflammatory activity using albumin denaturation and membrane stabilization. The present study is the first effort done to synthesize of Cu-NPs from the extract of M. pinnata flower. Consequently, to authenticate the results and to establish the antioxidant, antibacterial, an anti-diabetic and anti-inflammatory agent, in vivo studies are made in the molecular level.
71 citations
TL;DR: Gold nanoparticles have a range of applications in medicine, diagnostics, catalysis, and sensors because of their significant key roles in important fields and can be accredited to a combination of optical, physical, and chemical properties as well as the miscellany of size, shape, and surface composition that has been adopted through green synthesis methods.
Abstract: The hazardous effects of current nanoparticle synthesis methods have steered researchers to focus on the development of newer environmentally friendly and green methods for synthesizing nanoparticles using nontoxic chemicals. The development of environmentally friendly methods of nanoparticle synthesis with different sizes and shapes is one of the pressing challenges for the current nanotechnology. Several novel green approaches for the synthesis of AuNPs have been explored using different natural sources, such as plants, algae, bacteria, and fungi. Among organisms, algae and blue-green algae are of particular interest for nanoparticle synthesis. Gold nanoparticles (AuNPs) have a range of applications in medicine, diagnostics, catalysis, and sensors because of their significant key roles in important fields. AuNPs have attracted a significant interest for use in a variety of applications. The widespread use of AuNPs can be accredited to a combination of optical, physical, and chemical properties as well as the miscellany of size, shape, and surface composition that has been adopted through green synthesis methods.
69 citations
TL;DR: A new heterotrophic nitrifying–aerobic denitrifying bacterium was isolated and named as Pseudomonas mendocina TJPU04, which maintains high nitrogen removal efficiency over a wide range of nitrogen concentrations and showed efficient nitrogen removal performance in the presence of high concentration of salt and nitrogen.
Abstract: Excess inorganic nitrogen in water poses a severe threat to enviroment. Removal of inorganic nitrogen by heterotrophic nitrifying–aerobic denitrifying microorganism is supposed to be a promising and applicable technology only if the removal rate can be maintained sufficiently high in real wastewater under various conditions, such as high concentration of salt and wide range of different nitrogen concentrations. Here, a new heterotrophic nitrifying–aerobic denitrifying bacterium was isolated and named as Pseudomonas mendocina TJPU04, which removes NH4+-N, NO3−-N and NO2−-N with average rate of 4.69, 5.60, 4.99 mg/L/h, respectively. It also maintains high nitrogen removal efficiency over a wide range of nitrogen concentrations. When concentration of NH4+-N, NO3−-N and NO2−-N was up to 150, 150 and 50 mg/L, 98%, 93%, and 100% removal efficiency could be obtained, respectively, after 30-h incubation under sterile condition. When it was applied under non-sterile condition, the ammonia removal efficiency was slightly lower than that under sterile condition. However, the nitrate and nitrite removal efficiencies under non-sterile condition were significantly higher than those under sterile condition. Strain TJPU04 also showed efficient nitrogen removal performance in the presence of high concentration of salt and nitrogen. In addition, the removal efficiencies of NH4+-N, NO3−-N and TN in real wastewater were 91%, 52%, and 75%, respectively. These results suggest that strain TJPU04 is a promising candidate for efficient removal of inorganic nitrogen in wastewater treatment.
58 citations
TL;DR: A model-assisted Design of Experiments concept is introduced for the knowledge-based reduction of boundary values, where the parameters of a mathematical process model are estimated and the investigated factor combinations are simulated instead of experimentally derived.
Abstract: Design of Experiments methods offer systematic tools for bioprocess development in Quality by Design, but their major drawback is the user-defined choice of factor boundary values. This can lead to several iterative rounds of time-consuming and costly experiments. In this study, a model-assisted Design of Experiments concept is introduced for the knowledge-based reduction of boundary values. First, the parameters of a mathematical process model are estimated. Second, the investigated factor combinations are simulated instead of experimentally derived and a constraint-based evaluation and optimization of the experimental space can be performed. The concept is discussed for the optimization of an antibody-producing Chinese hamster ovary batch and bolus fed-batch process. The same optimal process strategies were found if comparing the model-assisted Design of Experiments (4 experiments each) and traditional Design of Experiments (16 experiments for batch and 29 experiments for fed-batch). This approach significantly reduces the number of experiments needed for knowledge-based bioprocess development.
57 citations
TL;DR: The results indicated a higher growth, leading to a dominant population in unsterilized conditions and higher PHB production, showed the conditions for halophilic PHA producers to be later implemented at a larger scale.
Abstract: Polyhydroxybutyrates (PHB) are biodegradable polymers that are produced by various microbes, including Ralstonia, Pseudomonas, and Bacillus species. In this study, a Vibrio proteolyticus strain, which produces a high level of polyhydroxyalkanoate (PHA), was isolated from the Korean marine environment. To determine optimal growth and production conditions, environments with different salinity, carbon sources, and nitrogen sources were evaluated. We found that the use of a medium containing 2% (w/v) fructose, 0.3% (w/v) yeast extract, and 5% (w/v) sodium chloride (NaCl) in M9 minimal medium resulted in high PHA content (54.7%) and biomass (4.94 g/L) over 48 h. Addition of propionate resulted in the production of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (P(HB-co-HV)) copolymer as propionate acts as a precursor for the HV unit. In these conditions, the bacteria produced poly(3-hydroxybutyrate-co-3-hydroxyvalerate) containing a 15.8% 3HV fraction with 0.3% propionate added as the substrate. To examine the possibility of using unsterilized media with high NaCl content for PHB production, V. proteolyticus was cultured in sterilized and unsterilized conditions. Our results indicated a higher growth, leading to a dominant population in unsterilized conditions and higher PHB production. This study showed the conditions for halophilic PHA producers to be later implemented at a larger scale.
55 citations
TL;DR: This article aims to present a review regarding different extraction techniques of biopolymers from waste using bio-based methods and advocates the implementation of biomass waste from food, organic, and other bio- based industries that revolutionizes the stance ofBiopolymer in various emerging fields.
Abstract: Regardless of considerable progress in synthetic plastic or polymer-based industry, its low biodegradability is a critical issue. Nevertheless, natural “biopolymers” are gradually replacing them for being inherently biodegradable, eco-friendly with other unique properties. This article aims to present a review regarding different extraction techniques of biopolymers [natural (cellulose, chitin, lignin, pectin, starch, xylan), synthetic (polyglycolic acid (PGA), polylactic acid (PLA), polycaprolactone (PCL), polyvinyl alcohol (PVA), polymethayl methacrylate (PMMA)] from waste using bio-based methods. The role of bio-based techniques in terms of conventional/ecologically stable strategies for biomass pre-treatment was investigated for proper utilization of waste. The review summarizes strong interplay between technological and future challenges of biopolymer extraction from waste and paints a discussion of how conventional resources could be replaced with more environmentally friendly materials. Therefore, we advocate the implementation of biomass waste from food, organic, and other bio-based industries that revolutionizes the stance of biopolymer in various emerging fields.
48 citations
TL;DR: The synthesized AgNPs showed an excellent photocatalytic degradation of methylene blue dye in less than 3 h under visible light proving their potential as a catalytic agent for bioremediation for next-generation dye degradation in effluent treatment and proposing promising ways for the valorization of the waste fermentation supernatant left after cell harvesting and desired metabolite extraction.
Abstract: The present study reports the optimization of a green method for the synthesis of silver nanoparticles (AgNPs) via reduction of Ag+ ions using cell-free supernatant of mutant Bacillus licheniformis M09. UV–Visible spectroscopy showing an absorption peak at ~ 430 nm confirmed the synthesis of AgNPs. Transmission electron microscope (TEM) analysis exhibited spherical AgNPs within the size range of 10–30 nm. Fourier transform infrared (FTIR) measurements assured the presence of effective functional molecules which could be responsible for stabilizing the AgNPs. X-ray diffraction (XRD) pattern verified the crystalline nature of AgNPs. Furthermore, the synthesized AgNPs showed an excellent photocatalytic degradation of methylene blue dye in less than 3 h under visible light proving their potential as a catalytic agent for bioremediation for next-generation dye degradation in effluent treatment. The AgNPs demonstrated antimicrobial activity against Gram-positive and Gram-negative foodborne pathogens which endorsed its suitability as agents to extend shelf-life in food packaging and food safety applications. The results also revealed a strong concentration-dependent cytotoxicity of AgNPs against human breast adenocarcinoma cells (MCF-7), while 15.07 µg/mL of IC50 was attained. The outcome suggests the possible application of these AgNPs in nanomedicine formulations. Thus, these findings propose promising ways for the valorization of the waste fermentation supernatant left after cell harvesting and desired metabolite extraction.
45 citations
TL;DR: This study evaluated the production of cellulolytic enzymes from different agricultural residues and found that all enzymatic activities were highly stable at 40 °C at a pH range of 4.5–5.5.
Abstract: This study evaluated the production of cellulolytic enzymes from different agricultural residues. The crude enzyme extract produced was characterized and applied for saccharification of some agricultural residues. Maximum cellulolytic activities were obtained using soybean hulls. All enzymatic activities were highly stable at 40 °C at a pH range of 4.5–5.5. For stability at low temperatures, the enzyme extract was stored at freezing temperature and cooling for about 290 days without major loss of activity. The Km values found for total cellulase (FPase), endoglucanase (CMCase), and xylanase were 19.73 mg ml−1, 0.65 mg ml−1, and 22.64 mg ml−1, respectively, and Vmax values were 0.82 mol min−1 mg−1, 0.62 mol min−1 mg−1, and 104.17 mol min−1 mg−1 to cellulose, carboxymethyl cellulose, and xylan, respectively. In the saccharification tests, the total amount of total reducing sugars (TRS) released from 1 g of soybean hulls catalyzed by the enzymes present in the crude enzyme extract was 0.16 g g−1 dry substrate.
44 citations
TL;DR: This review describes and compares the efficiency of different conventional and novel techniques that can be used for cell disruption and recovery of bio-molecules from Nannochloropsis sp.
Abstract: Microalgae of Nannochloropsis sp. present valuable source of bio-molecules (pigments, lipids, proteins) that have nutritional potential for the prevention and treatment of human diseases. Moreover, some species of Nannochloropsis are the promising sources of biofuels and excellent candidates for the replacement of classical biofuel crops. This review describes and compares the efficiency of different conventional and novel techniques that can be used for cell disruption and recovery of bio-molecules from Nannochloropsis sp. Classification of different extraction techniques includes chemical, enzymatic, mechanical and other physical methods. The detailed analysis of extraction efficiency assisted by pressure and temperature (subcritical and supercritical fluids, hydrothermal liquefaction), ultrasound, microwaves, and pulsed electric energy (pulsed electric fields and high voltage electrical discharges) is presented. The general discussion includes comparison between techniques, their effectiveness for cell disruption and selectivity of bio-molecules extraction from Nannochloropsis sp. The cost-effectiveness, benefits and limitations of different techniques are also analyzed.
43 citations
TL;DR: The present results confirmed that C. sorokiniana isolate BENHA721_ABO4 grown in secondary effluent municipal wastewater offers real potential for future application in wastewater treatment and biodiesel production.
Abstract: The isolated microalga Chlorella sorokiniana BENHA721_ABO4 was grown in Bold’s basal medium (BBM) as a control, municipal wastewater (WW), and wastewater enriched with BBM elements (WW+). Cultivation in WW+ showed the highest cell number which represented 25.3 and 47.3% over that grown in WW and BBM, respectively. However, rapid growth in WW+ was accompanied by significant reduction in lipid content. Due to lipid accumulation in WW, it showed the maximum significant lipid productivity of 16.2 mg L−1 day−1. Microalgae cultivation in WW for 10 days showed 74.2, 83.3, and 78.0% removal efficiency for NO3–N, NH3–N and TP, respectively. In addition, growth in WW significantly reduced polyunsaturated fatty acids by 36.0% with respect to BBM in favor of monounsaturated fatty acids. The present results confirmed that C. sorokiniana isolate BENHA721_ABO4 grown in secondary effluent municipal wastewater offers real potential for future application in wastewater treatment and biodiesel production.
TL;DR: Results indicate the lethal effect of green-synthesized silver NPs on A. gossypii, in vitro.
Abstract: Simpler and biocompatible greener approaches for the assembly of nanoparticles (NPs) have been the focus lately which have minimum environmental damage and often entails the use of natural biomolecules to synthesize NPs. Such greener synthesis of nanoparticles has capitalized on the use of microbes, fungi, and plants using biological resources. In this study, Periplaneta americana (American cockroach) wings' extract (chitin-rich) is studied as a novel biomaterial for the first time to synthesize silver NPs (less than 50 nm); chitin is the second most abundant polymer after cellulose on earth. The physicochemical properties of these NPs were analyzed using UV–visible spectroscopy, X-ray diffraction, and transmission electron microscopy (TEM). The insecticidal effect of ensuing NPs was examined on the mortality of Aphis gossypii under laboratory conditions; 48 h after treatments of A. gossypii with silver NPs (100 μg/ml), the mortality rate in treated aphids was about 40% (an average), while an average percentage of losses in the control sample was about 10%. These results indicate the lethal effect of green-synthesized silver NPs on A. gossypii, in vitro. Greener synthesis of silver nanoparticles using American cockroach wings and their insecticidal activities.
TL;DR: The result showed that Hortaea sp.
Abstract: Polycyclic aromatics hydrocarbons (PAHs) are ubiquitous and toxic pollutants that are dangerous to humans and living organism in aquatic environment. Normally, PAHs has lower molecular weight such as phenanthrene and naphthalene that are easy and efficient to degrade, but high-molecular-weight PAHs such as chrysene and pyrene are difficult to be biodegraded by common microorganism. This study investigated the isolation and characterization of a potential halophilic bacterium capable of utilizing two high-molecular-weight PAHs. At the end of the experiment (25–30 days of incubation), bacterial counts have reached a maximum level (over 40 × 1016 CFU/mL). The highest biodegradation rate of 77% of chrysene in 20 days and 92% of pyrene in 25 days was obtained at pH 7, temperature 25 °C, agitation of 150 rpm and Tween 80 surfactant showing to be the most impressive parameters for HMWPAHs biodegradation in this research. The metabolism of initial compounds revealed that Hortaea sp. B15 utilized pyrene to form phthalic acid while chrysene was metabolized to form 1-hydroxy-2-naphthoic acid. The result showed that Hortaea sp. B15 can be promoted for the study of in situ biodegradation of high molecular weight PAH.
TL;DR: The green microalga Scenedesmus bajacalifornicus BBKLP-07 is a rich source of biological active compounds and nutraceuticals and can be exploited for commercial applications.
Abstract: Microalgae are photosynthetic eukaryotes which are primary producers in the food chain and also excellent sources for bioactive compounds such as alkaloids, flavonoids, phenols, saponins and other fine chemicals. In the present study, the microalga Scenedesmus bajacalifornicus BBKLP-07 was subjected to soxhlet extraction using solvents like chloroform, acetone, ethanol, methanol and aqueous solvents. All the solvents were tested for the presence of phytochemical constituents such as alkaloids, flavonoids, glycosides, phenols, lignin's, saponins, sterols, tannins, anthraquinone and reducing sugar using the standard procedures. Furthermore, all the crude extracts were subjected to antidiabetic, antioxidant, anti-inflammatory and antimicrobial activities. Antidiabetic activity of the microalgal extracts was observed maximum in Aqueous extract. Methanolic extracts have shown maximum antioxidant activity and chloroform extracts have exhibited highest anti-inflammatory effects. Antimicrobial activities were tested against E.coli, S, typhi, C.perfringens and B.subtilis bacteria and fungi A.niger, and C. albicans. Therefore, the green microalga Scenedesmus bajacalifornicus BBKLP-07 is a rich source of biological active compounds and nutraceuticals and can be exploited for commercial applications.
TL;DR: The present review covers some recent developments in sustainable bioreactor scale production of PHAs and identifies some areas in which future research in this field might be focused.
Abstract: Polyhydroxyalkanoates (PHAs) are biological plastics that are sustainable alternative to synthetic ones. Numerous microorganisms have been identified as PHAs producers. They store PHAs as cellular inclusions to use as an energy source backup. They can be produced in shake flasks and in bioreactors under defined fermentation and physiological culture conditions using suitable nutrients. Their production at bioreactor scale depends on various factors such as carbon source, nutrients supply, temperature, dissolved oxygen level, pH, and production modes. Once produced, PHAs find diverse applications in multiple fields of science and technology particularly in the medical sector. The present review covers some recent developments in sustainable bioreactor scale production of PHAs and identifies some areas in which future research in this field might be focused.
TL;DR: The present work concluded that the MO-1 was successfully degraded by C. aurelium RY06 and transformed to be maleic acid and to be isophtalic acid.
Abstract: Due to environmental concern, the research to date has tended to focus on how textile dye removal can be carried out in a greener manner. Therefore, this study aims to evaluate the decolorization and biotransformation pathway of Mordant Orange-1 (MO-1) by Cylindrocephalum aurelium RY06 (C. aurelium RY06). Decolorization study was conducted in a batch experiment including the investigation of the effects of physio-chemical parameters. Enzymatic activity of C. aurelium RY06 during the decolorization was also investigated. Moreover, transformation and biodegradation of MO-1 by C. aurelium RY06 were observed using the gas chromatography–mass spectrometry. Manganese peroxidase, lignin peroxidase, laccase, 1,2-dioxygenase, and 2,3-dioxygenase enzymes were detected during the decolorization. In general, the present work concluded that the MO-1 was successfully degraded by C. aurelium RY06 and transformed to be maleic acid and to be isophtalic acid.
TL;DR: SBM is a promising carbon source for inulinase production by Aspergillus niger in shake flask fermentation and the first report on the determination of some properties of A. niger A42 (ATCC 204,447) inulinases is reported.
Abstract: Inulinases are used for the production of high-fructose syrup and fructooligosaccharides, and are widely utilized in food and pharmaceutical industries. In this study, different carbon sources were screened for inulinase production by Aspergillus niger in shake flask fermentation. Optimum working conditions of the enzyme were determined. Additionally, some properties of produced enzyme were determined [activation (Ea)/inactivation (Eia) energies, Q10 value, inactivation rate constant (kd), half-life (t1/2), D value, Z value, enthalpy (ΔH), free energy (ΔG), and entropy (ΔS)]. Results showed that sugar beet molasses (SBM) was the best in the production of inulinase, which gave 383.73 U/mL activity at 30 °C, 200 rpm and initial pH 5.0 for 10 days with 2% (v/v) of the prepared spore solution. Optimum working conditions were 4.8 pH, 60 °C, and 10 min, which yielded 604.23 U/mL, 1.09 inulinase/sucrase ratio, and 2924.39 U/mg. Additionally, Ea and Eia of inulinase reaction were 37.30 and 112.86 kJ/mol, respectively. Beyond 60 °C, Q10 values of inulinase dropped below one. At 70 and 80 °C, t1/2 of inulinase was 33.6 and 7.2 min; therefore, inulinase is unstable at high temperatures, respectively. Additionally, t1/2, D, ΔH, ΔG values of inulinase decreased with the increase in temperature. Z values of inulinase were 7.21 °C. Negative values of ΔS showed that enzymes underwent a significant process of aggregation during denaturation. Consequently, SBM is a promising carbon source for inulinase production by A. niger. Also, this is the first report on the determination of some properties of A. niger A42 (ATCC 204,447) inulinase.
TL;DR: It is shown that bootstrap aggregation significantly decreases the prediction mean squared error of new batch experiments for all three designs and the availability of several predictions allowed computing error bounds for the different parts of the model, which provides an additional insight into the variation of predictions within the model components.
Abstract: Hybrid semi-parametric modeling, combining mechanistic and machine-learning methods, has proven to be a powerful method for process development. This paper proposes bootstrap aggregation to increase the predictive power of hybrid semi-parametric models when the process data are obtained by statistical design of experiments. A fed-batch Escherichia coli optimization problem is addressed, in which three factors (biomass growth setpoint, temperature, and biomass concentration at induction) were designed statistically to identify optimal cell growth and recombinant protein expression conditions. Synthetic data sets were generated applying three distinct design methods, namely, Box–Behnken, central composite, and Doehlert design. Bootstrap-aggregated hybrid models were developed for the three designs and compared against the respective non-aggregated versions. It is shown that bootstrap aggregation significantly decreases the prediction mean squared error of new batch experiments for all three designs. The number of (best) models to aggregate is a key calibration parameter that needs to be fine-tuned in each problem. The Doehlert design was slightly better than the other designs in the identification of the process optimum. Finally, the availability of several predictions allowed computing error bounds for the different parts of the model, which provides an additional insight into the variation of predictions within the model components.
TL;DR: Evidently, biofilm reactors present a reliable strategy to address the operational issues that occur during MK-7 biosynthesis on an industrial scale production.
Abstract: Menaquinone-7 (MK-7) as the most important form of Vitamin K has been reported to have miraculous benefits such as preventing cardiovascular diseases and osteoporosis along with antitumor effects. Therefore, there have been numerous studies in the past decades to improve MK-7 production via microbial fermentation. Unfortunately, both solid and liquid state fermentation strategies that are utilized for MK-7 production, face fundamental operational and scale-up issues as well as intense heat and mass transfer problems during fermentation. In this regard, biofilm reactors seem to be a practical solution to overcome these issues and enhance the production in agitated liquid fermentation. Therefore, this study was undertaken to utilize biofilm reactors in investigating and optimizing different media components in a glycerol-based medium. Using response surface methodology, the effects of glycerol, yeast extract, and soytone were studied in the fermentation medium on MK-7 production in biofilm reactor. With a composition of 48.2 g/L of glycerol, 8.1 g/L of yeast extracts, 13.6 g/L of soytone and 0.06 g/L of K2HPO4, MK-7 concentrations could reach 14.7 ± 1.4 mg/L in biofilm reactors, which was 57% higher compared to the MK-7 concentration achieved in suspended-cell reactors under similar conditions, while glycerol was depleted by the end of the fifth day in biofilm reactors, but glycerol was never depleted in suspended-cell reactors. Evidently, biofilm reactors present a reliable strategy to address the operational issues that occur during MK-7 biosynthesis on an industrial scale production.
TL;DR: A two-step cultivation strategy to efficiently produce astaxanthin using microalgae is proposed, which suggested that the ROS, MAPK and astxanthin biosynthetic gene expression was involved in astaxantin biosynthesis in H. pluvialis under different culture media conditions.
Abstract: In the present study, the effects of four different culture media on the growth, astaxanthin production and morphology of Haematococcus pluvialis LUGU were studied under two-step cultivation. The interactions between astaxanthin synthesis and secondary messengers, reactive oxygen species (ROS) and mitogen-activated protein kinases (MAPK) were also investigated. In the first green vegetative cell stage, maximal biomass productivity (86.54 mg L−1 day−1) was obtained in BBM medium. In the induction stage, the highest astaxanthin content (21.5 mg g−1) occurred in BG-11 medium, which was higher than in any other media. The expressions of MAPK and astaxanthin biosynthetic genes in BG-11 were higher than in any other media, whereas the ROS content was lower. Biochemical and physiological analyses suggested that the ROS, MAPK and astaxanthin biosynthetic gene expression was involved in astaxanthin biosynthesis in H. pluvialis under different culture media conditions. This study proposes a two-step cultivation strategy to efficiently produce astaxanthin using microalgae.
TL;DR: Production and recovery of poly(3-hydroxybutyrate) P(3HB) from agro-industrial residues using Ralstonia eutropha strain with hemp hurd biomass hydrolysates sugars as a carbon source and ammonium chloride as the nitrogen source and results show that maximum hydrolysis yield was achieved.
Abstract: The present study describes production and recovery of poly(3-hydroxybutyrate) P(3HB) from agro-industrial residues. Production was conducted using Ralstonia eutropha strain with hemp hurd biomass hydrolysates sugars as a carbon source and ammonium chloride as the nitrogen source. Results show that maximum hydrolysis yield of 72.4% was achieved with total sugar hydrolysate concentration (i.e., glucose and xylose) of 53.0 g/L. Sugar metabolism by R. eutropha showed preference for glucose metabolism over xylose. Under optimum conditions, cells can accumulate P(3HB) polymer in quantity up to 56.3 wt% of the dry cell weight. This corresponds to total production of 13.4 g/L (productivity of 0.167 g/L h). Nitrogen source showed no adverse effect on P(3HB) biosynthesis, but rather on cell growth. Among several examined recovery techniques, ultrasonic-assisted sodium dodecyl sulfate (SDS) recovered bioplastic directly from the broth cell concentrate with P(3HB) content of 92%. Number average molecular weights (Mn) of final recovered bioplastic were in the range of 150–270 kDa with polydispersity index (Mw/Mn) in the range of 2.1–2.4.
TL;DR: The results showed that the transcriptional expression levels of all these genes in high yield strain AR-47 had increased compared with the starting strain KA-11, indicating that mutagenesis breeding still plays a vital role for obtaining strains with high kojic acid production.
Abstract: Kojic acid is a kind of secondary metabolites, whose biosynthesis pathway remains unclear to date. It is produced industrially by microbial fermentation, and thus, mutagenesis breeding still plays a vital role for obtaining strains with high kojic acid production. The starting strain KA-11 isolated from mildewed fruits was identified as Aspergillus oryzae and then subjected to a combined mutagenesis program including microwave mutagenesis, UV irradiation, heat-LiCl, atmospheric, and room temperature plasma (ARTP). The kojic acid production was increased by 47.0%, 87.1%, 126.2%, and 292.3% compared with the starting strain KA-11 after each mutagenesis stage. A mutant strain AR-47 with kojic acid production of 96.5 g/L in flask-shake fermentation was finally obtained. The fermentation time also decreased from 7 to 5 days. Real-time quantitative PCR was used to determine the transcriptional expression levels of genes that may be relevant to kojic acid biosynthesis, including kojA, kojR, kojT, AO090113000141, AO090113000143, AO090113000145, nrtA, and laeA. The results showed that the transcriptional expression levels of all these genes in high yield strain AR-47 had increased compared with the starting strain KA-11.
TL;DR: Covalent immobilization of steapsin lipase (SL) on Immobead-350 support matrix (IMB) is reported to make a robust biocatalytic system to work under supercritical carbon dioxide condition (Sc-CO2) to convert waste cooking sunflower oil into value-added energy chemical (biodiesel) in Sc- CO2.
Abstract: The present work reports covalent immobilization of steapsin lipase (SL) on Immobead-350 support matrix (IMB) to make a robust biocatalytic system to work under supercritical carbon dioxide condition (Sc-CO2). The developed biocatalyst (IMB:SL) was characterized in details and utilized to convert waste cooking sunflower oil (WCSO) into value-added energy chemical (biodiesel) in Sc-CO2. All reaction process parameters were optimized in detail which offered 86.33% yield of biodiesel from WCSO. The developed Sc-CO2 protocol is compared with the solvent-free conventional synthesis, which indicates almost twofold higher yield of biodiesel in Sc-CO2 media as compared to solvent-free condition. To extend the scope, we have tested fresh and waste cooking oils (WCO) from various sources, offering 81-94% yield of biodiesel. The biocatalyst activity was investigated in various parameters of supercritical condition to know the biocatalyst stability in Sc-CO2. Besides this, IMB:SL biocatalyst was effectively reused up to five recycle.
TL;DR: The transesterification of sunflower oil in a semi-continuous regime of alcohol improved the results, compared to the discontinuous regime, and those were similar to the obtained in a discontinued regime with step-by-step methanol addition.
Abstract: The transesterification of sunflower oil with methanol, using immobilized lipase enzymes as catalysts, was studied. The process was carried out in a semi-continuous mode. Temperature (30–50 °C), methanol flow (0.024–0.04 ml/min), kind of enzyme (Lipozyme 62350, Lipozyme TL-IM, Novozym 435 and Pseudomonas cepacia Sol–Gel-AK) and enzyme concentrations (1.25–10% by weight) were the operating variables. The final product was characterized by the EN 14214 standard. All the parameters, except for cold filter plugging point, were similar to a diesel fuel. For low methanol flows, reaction rate was proportional to methanol concentration. High flows caused catalyst deactivation. Novozyme 435, Lipozyme TL-IM and Lipozyme 62350 showed similar maximum reaction rates, but Novozyme 435 was more resistant to deactivation. Pseudomonas cepacia hardly obtained 1% conversion. The catalyst concentration, up to 2.5%, had a positive effect on the reaction rate and conversion. The optimum temperature was 40 °C. The initial reaction rate was in line with the Arrhenius law, up to 50 °C. By differential and integral methods, the Michaelis–Menten, competitive inhibition and ping-pong bi–bi kinetic parameters were determined. The transesterification of sunflower oil in a semi-continuous regime of alcohol improved the results, compared to the discontinuous regime, and those were similar to the obtained ones in a discontinuous regime with step-by-step methanol addition. The lipase that showed the best yield and higher resistance to deactivation was Novozym 435. The kinetic models that forecast the deactivation of lipases by an inhibitor described the experimental behavior properly.
TL;DR: The results show that the addition of immobilized bacteria with IONs resulted in a lower water absorption and volume of permeable pore space, and CaCO3 was precipitated in bio-concrete specimen as a result of microbial biosynthesis.
Abstract: Despite the advantages of concrete, it has a pore structure and is susceptible to cracking The initiated cracks as well as pores and their connectivity accelerate the structure degradation by permitting aggressive substances to flow into the concrete matrix This phenomenon results in a considerable repair and maintenance costs and decreases the concrete lifespan In recent years, biotechnological approach through immobilization of bacteria in/or protective vehicles has emerged as a viable solution to address this issue However, the addition of macro- or micro scale size particles can decrease the integrity of matrix In this study, the immobilization of bacteria with magnetic iron oxide nanoparticle (ION) was proposed to protect the bacterial cell and evaluate their effect on healing the concrete pore space The results show that the addition of immobilized bacteria with IONs resulted in a lower water absorption and volume of permeable pore space Crystal analysis using scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDS) revealed that CaCO3 was precipitated in bio-concrete specimen as a result of microbial biosynthesis
TL;DR: Environmental conditions, including light quality, temperature and light wavelength mixing ratio, were individually altered to enhance the cell growth rate and lutein production in strain JSC4 and the two-stage strategy proved to be effective markedly improving luteIn content from 2.52 to 4.24 mg/g.
Abstract: The marine microalga Chlamydomonas sp. JSC4 was examined for its potential as a lutein producer. Environmental conditions, including light quality, temperature and light wavelength mixing ratio, were individually altered to enhance the cell growth rate and lutein production in strain JSC4. Results showed that optimal cell growth was obtained under white light and a temperature of 35 °C, while the optimal lutein content was obtained under blue light and a lower temperature of 20–25 °C. The best lutein production occurred when using a mixing ratio of 3:1 (white light: blue light). Strategies related to light quality and temperature (namely, temperature-gradient and two-stage strategies) were then used to further improve lutein production. Among them, the two-stage strategy proved to be effective markedly improving lutein content from 2.52 to 4.24 mg/g and resulting in the highest lutein productivity of 3.25 mg/L/day.
TL;DR: Investigation of the immobilization of lipase NS-40116 in polyurethane foam using a biopolyol obtained through the enzymatic glycerolysis between castor oil and glycerol, catalyzed by the commercial lipase Novozym 435 for the PUF formation proves that the support obtained using environmentally friendly techniques is applicable.
Abstract: The use of green sources for materials synthesis has gained popularity in recent years. This work investigated the immobilization of lipase NS-40116 (Thermomyces lanuginosus lipase) in polyurethane foam (PUF) using a biopolyol obtained through the enzymatic glycerolysis between castor oil and glycerol, catalyzed by the commercial lipase Novozym 435 for the PUF formation. The reaction was performed to obtain biopolyol resulting in the conversion of 64% in mono- and diacylglycerol, promoting the efficient use of the reaction product as biopolyol to obtain polyurethane foam. The enzymatic derivative with immobilized lipase NS-40116 presented apparent density of 0.19 ± 0.03 g/cm3 and an immobilization yield was 94 ± 4%. Free and immobilized lipase NS-40116 were characterized in different solvents (methanol, ethanol, and propanol), temperatures (20, 40, 60 and 80 °C), pH (3, 5, 7, 9 and 11) and presence of ions Na+, Mg++, and Ca++. The support provided higher stability to the enzyme, mainly when subjected to acid pH (free lipase lost 80% of relative activity after 360 h of contact, when the enzymatic derivative lost around 22%) and high-temperature free lipase lost 50% of relative activity, while the immobilized remained 95%. The enzymatic derivative was also used for esterification reactions and conversions around 66% in fatty acid methyl esters, using abdominal chicken fat as feedstock, were obtained in the first use, maintaining this high conversion until the fourth reuse, proving that the support obtained using environmentally friendly techniques is applicable.
TL;DR: Analysis of the metabolomics of the microalga Scenedesmus obliquus cultivated in 24:0 and 12:12 (light:dark) photoperiods and different phases of cell growth found that metabolite production could be related to both the environmental conditions under which cultivation occurred and to the different concentrations of products present in the S. ob liquus biomass.
Abstract: Environmental factors directly affect the growth and composition of microalgal biomass. Therefore, the present work analyzed the metabolomics (amino acids, organic acids, and fatty acids) of the microalga Scenedesmus obliquus cultivated in 24:0 and 12:12 (light:dark) photoperiods and different phases of cell growth. Furthermore, the metabolites were related to protein, lipid, and chlorophyll contents at the end of cultivation. The highest biomass concentration (4020 mg L− 1) and protein (47.3%) were obtained in culture under constant illumination. The cultivation 12:12 (light:dark) photoperiod triggered higher production of lipids (23.0%) and chlorophylls (26.4 mg g− 1) by S. obliquus. Microalgal metabolites were greatly affected by photoperiod and by phase of cell growth. Thus, metabolite production could be related to both the environmental conditions under which cultivation occurred and to the different concentrations of products (proteins, lipids, and chlorophylls) present in the S. obliquus biomass.
TL;DR: HH permitted an effective release overall of intracellular compounds from P. kessleri microalgae including a large quantity of proteins, whose release was 4.9 times higher than that obtained by HVED.
Abstract: Treatments with high-voltage electrical discharges (HVED) and high-pressure homogenization (HPH) were studied and compared for the release of ionic components, carbohydrates, proteins, and pigments from microalgae Parachlorella kessleri (P kessleri) Suspensions (1% w/w) of microalgae were treated by HVED (40 kV/cm, 1–8 ms) or by HPH (400–1200 bar, 1–10 passes) Particle-size distribution (PSD) and microscopic analyses were used to detect the disruption and damage of cells HVED were very effective for the extraction of ionic cell components and carbohydrates (421 mg/L after 8 ms of the treatment) However, HVED were ineffective for pigments and protein extraction The concentration of proteins extracted by HVED was just 750 mg/L and did not exceed 15% of the total quantity of proteins HPH permitted an effective release overall of intracellular compounds from P kessleri microalgae including a large quantity of proteins, whose release (at 1200 bar) was 49 times higher than that obtained by HVED Consequently, HVED can be used at the first step of the overall extraction process for the selective recovery of low-molecular-weight components HPH can be then used at the second step for the recovery of remaining cell compounds
TL;DR: A global strategy to identify interactions between cultivation parameters for valorization of food industry by-products is described, giving the opportunity to optimize the process depending on the objective and making an “in silico” pre-evaluation of the process conditions.
Abstract: Submerged fermentation (SmF) is an attractive biotechnological option for waste treatment, generating fungal bioprotein from food industry by-products. Using different Rhizopus sp. strains as fermentation agents, this paper describes a global strategy to identify interactions between cultivation parameters (pH 4.75–7.75, 7.5–82.5 g/l glucose, 0.75–3.75 g/l nitrogen, incubation time up to 5 days) for valorization of food industry by-products. Selected parameters and/or their interactions are critical for most of the proposed resulting values, giving the opportunity to optimize the process depending on the objective and making an “in silico” pre-evaluation of the process conditions. SmF of orange molasses leads to a high biomass and protein yield (11.9 g biomass/l and 4.0 g protein/l), with 43.1 ± 0.1% of essential amino acids and chemical oxygen demand (COD) reduction of almost 50%. Experiments with cheese whey result in 76.3 ± 1.1% of glucose consumption and a biomass production of 5.6 ± 2.2 g/l with 48.9 ± 5.1% of essential amino acids. SmF of orange molasses and cheese whey could contribute to promoting a sustainable feed industry while reducing by-product treatment.