Showing papers on "Solid-state fermentation published in 2012"

Solid state and submerged fermentation for the production of bioactive substances: a comparative study

Abstract: Fermentation has been widely used for the production of a wide variety of substances that are highly beneficial to individuals and industry. Over the years, fermentation techniques have gained immense importance due to their economic and environmental advantages. Ancient techniques have been further modified and refined to maximize productivity. This has also involved the development of new machinery and processes. Two broad fermentation techniques have emerged as a result of this rapid development: Submerged Fermentation (SmF) and Solid State Fermentation (SSF). Discovery of the beneficial activity of several secondary metabolites produced by microorganism s (bioactive compounds) has resulted in the further exploration of fermentation as a production technique for these compounds. At the research level, both SSF and SmF have been used; however, some techniques yielded better results than others. Much work still needs to be done to identify the best fermentation technique for each bioactive compound. This paper reviews different fermentation techniques for the production of bioactive compounds. Comparison of these techniques for the identification of the better technique is also dealt with.

Isolation, Purification, and Characterization of Xylanase Produced by a New Species of Bacillus in Solid State Fermentation

Abstract: A thermoalkalophilic new species of Bacillus, similar to Bacillus arseniciselenatis DSM 15340, produced extracellular xylanase under solid state fermentation when wheat bran is used as carbon source. The extracellular xylanase was isolated by ammonium sulfate (80%) precipitation and purified using ion exchange chromatography. The molecular weight of xylanase was ~29.8 kDa. The optimum temperature and pH for the enzyme activity were 50°C and pH 8.0. The enzyme was active on birchwood xylan and little active on p-nitrophenyl xylopyranoside but not on Avicel, CMC, cellobiose, and starch, showing its absolute substrate specificity. For birchwood xylan, the enzyme gave a Km 5.26 mg/mL and Vmax 277.7 μmol/min/mg, respectively. In addition, the xylanase was also capable of producing high-quality xylo-oligosaccharides, which indicated its application potential not only in pulp biobleaching processes but also in the nutraceutical industry.

Correlation between agar plate screening and solid-state fermentation for the prediction of cellulase production by Trichoderma strains.

Abstract: The viability of converting biomass into biofuels and chemicals still requires further development towards the reduction of the enzyme production costs. Thus, there is a growing demand for the development of efficient procedures for selection of cellulase-producing microorganisms. This work correlates qualitative screening using agar plate assays with quantitative measurements of cellulase production during cultivation under solid-state fermentation (SSF). The initial screening step consisted of observation of the growth of 78 preselected strains of the genus Trichoderma on plates, using microcrystalline cellulose as carbon source. The 49 strains that were able to grow on this substrate were then subjected to a second screening step using the Congo red test. From this test it was possible to select 10 strains that presented the highest enzymatic indices (EI), with values ranging from 1.51 to 1.90. SSF cultivations using sugarcane bagasse and wheat bran as substrates were performed using selected strains. The CG 104NH strain presented the highest EGase activity (25.93 UI·g−1). The EI results obtained in the screening procedure using plates were compared with cellulase production under SSF. A correlation coefficient () of 0.977 was obtained between the Congo red test and SSF, demonstrating that the two methodologies were in good agreement.

Comparative study of the effects of solid-state fermentation with three filamentous fungi on the total phenolics content (TPC), flavonoids, and antioxidant activities of subfractions from oats (Avena sativa L.).

Abstract: The aim of present work was to investigate the effect of solid-state fermentation with filamentous fungi (Aspergillus oryzae var. effuses, Aspergillus oryzae, and Aspergillus niger) on total phenolics content (TPC), flavonoids, and antioxidant activities of four subfractions of oat, namely, n-hexane, ethyl acetate (EA), n-butanol, and water, and compare them to their corresponding subfractions of unfermented oat. The TPC and total flavonoids increased dramatically, especially in EA subfractions (p < 0.05). The levels of antioxidant activity of subfractions were also significantly enhanced (p < 0.05). The highest antioxidant activities were also found in the EA subfractions. The polyphenols in EA were analyzed by high-performance liquid chromatography at 280 nm. Most polyphenols were increased remarkably, especially ferulic and caffeic acids. There was a clear correlation between the TPC and antioxidant activity. In conclusion, fungi fermentation is a potential bioprocess for increasing the TPC, flavonoids, and antioxidant activities of oat-based food.

Using Amazon forest fungi and agricultural residues as a strategy to produce cellulolytic enzymes

Abstract: The successful strategy to produce cellulolytic enzymes includes both microorganism selection and improved fermentation process conditions. This work describes the isolation, screening and selection of biomass-degrading fungi species from the Amazon forest and analyzes the enzymatic complex produced by a selected strain of Aspergillus fumigatus cultivated using different agro-industrial residues (wheat bran, sugarcane bagasse, soybean bran, and orange peel) as substrate in solid state fermentation (SSF). The profile of endoglucanase (CMCase), FPase, β-glucosidase and xylanase enzymatic activities obtained during 120 h of cultivation is presented. Enzyme activities up 160.1 IU g−1 for CMCase, 5.0 FPU g−1 for FPAse, 105.82 IU g−1 for β-glucosidase and 1055.62 IU g−1 for xylanase were achieved. The enzymatic extract with higher CMCase activity was used to run a zymogram analysis that showed 3 bands of endoglucanase activity. Characterization studies of this extract showed that the CMCase was most active at either 65 °C or pH 3–3.5, indicating that this microorganism produces a thermophilic and acid endoglucanase. These data demonstrate that the fungal isolates from the Amazon forest are a potential source of cellulases and xylanases, providing support to further studies related to the use of these microorganisms to obtain the enzymes needed for biomass conversion.

Bio-modification of soybean meal with Bacillus subtilis or Aspergillus oryzae

Abstract: The nutritional quality of soybean meal (SBM) was improved via solid-state fermentation using the Aspergillus oryzae or Bacillus subtilis microbes in conical flasks. Compared to the control, the protein content in fermented soybean meal (FSBM) was increased by 8.37% and 0.34% with B. subtilis and A. oryzae , respectively, and their trypsin inhibitor contents were reduced by 96% and 82%, respectively. Furthermore, the concentrations of small-size proteins in FSBM were increased from 5% to 63% and from 5% to 35% by B. subtilis and A. oryzae , respectively, while the concentrations of large-size proteins were reduced from 40% to 2% and from 40% to 8%, respectively. Significantly lower levels of antigenic proteins were observed in FSBM compared to SBM. Also, FSBM exhibited a higher level of DPPH free radical-scavenging activity than did the control. The in vitro digestibility of crude protein by pepsin (IVDI) was increased strongly by fermentation. Fermentation with B. subtilis mediated a higher IVDI than did fermentation with A. oryzae . However, the in vitro digestibility of crude protein by pepsin and trypsin (IVDII) derived from B. subtilis and A. oryzae showed no significant difference from that of the control. In general, the protein content and anti-oxidation activity were increased and trypsin inhibitors and antigenic proteins were reduced in FSBM culture, indicating that it could be used as a new protein source in animal diets.

Metabolic and microbial community dynamics during the hydrolytic and acidogenic fermentation in a leach-bed process

Abstract: Biogas production from lignocellulosic feedstock not competing with food production can contribute to a sustainable bioenergy system. The hydrolysis is the rate-limiting step in the anaerobic digestion of solid substrates such as straw. Hence, a detailed understanding of the metabolic processes during the steps of hydrolysis and acidogenesis is required to improve process control strategies. The fermentation products formed during the acidogenic fermentation of maize silage as a model substrate in a leach-bed process were determined by gas and liquid chromatography. The bacterial community dynamics was monitored by terminal restriction fragment length polymorphism analysis. The community profiles were correlated with the process data using multivariate statistics. The batch process comprised three metabolic phases characterized by different fermentation products. The bacterial community dynamics correlated with the production of the respective metabolites. In phase 1, lactic and acetic acid fermentations dominated. Accordingly, bacteria of the genera Lactobacillus and Acetobacter were detected. In phase 2, the metabolic pathways shifted to butyric acid fermentation, accompanied by the production of hydrogen and carbon dioxide and a dominance of the genus Clostridium. In phase 3, phylotypes affiliated with Ruminococcaceae and Lachnospiraceae prevailed, accompanied by the formation of caproic and acetic acids, and a high gas production rate. A clostridial butyric type of fermentation was predominant in the acidogenic fermentation of maize silage, whereas propionic type fermentation was marginal. As the metabolite composition resulting from acidogenesis affects the subsequent methanogenic performance, process control should focus on hydrolysis/acidogenesis when solid substrates are digested.

Investigation of antimicrobial activity and statistical optimization of Bacillus subtilis SPB1 biosurfactant production in solid-state fermentation.

Abstract: During the last years, several applications of biosurfactants with medical purposes have been reported. Biosurfactants are considered relevant molecules for applications in combating many diseases. However, their use is currently extremely limited due to their high cost in relation to that of chemical surfactants. Use of inexpensive substrates can drastically decrease its production cost. Here, twelve solid substrates were screened for the production of Bacillus subtilis SPB1 biosurfactant and the maximum yield was found with millet. A Plackett-Burman design was then used to evaluate the effects of five variables (temperature, moisture, initial pH, inoculum age, and inoculum size). Statistical analyses showed that temperature, inoculum age, and moisture content had significantly positive effect on SPB1 biosurfactant production. Their values were further optimized using a central composite design and a response surface methodology. The optimal conditions of temperature, inoculum age, and moisture content obtained under the conditions of study were 37°C, 14 h, and 88%, respectively. The evaluation of the antimicrobial activity of this compound was carried out against 11 bacteria and 8 fungi. The results demonstrated that this biosurfactant exhibited an important antimicrobial activity against microorganisms with multidrug-resistant profiles. Its activity was very effective against Staphylococcus aureus, Staphylococcus xylosus, Enterococcus faecalis, Klebsiella pneumonia, and so forth.

Use of Agro-Industrial Wastes in Solid-State Fermentation Processes

Abstract: Large amount of wastes is generated every year from the industrial processing of agricultural raw materials. Most of these wastes are used as animal feed or burned as alternative for elimination. However, such wastes usually have a composition rich in sugars, minerals and proteins, and therefore, they should not be considered “wastes” but raw materials for other industrial processes. The presence of carbon sources, nutrients and moisture in these wastes provides conditions suitable for the development of microorganisms, and this open up great possibilities for their reuse in solid-state fermentation (SSF) processes, for example. Agro-industrial wastes can be used as solid support, carbon and/or nutrient source in SSF processes for the production of a variety of value-added compounds.

New perspectives of gibberellic acid production: a review

Abstract: The gibberellins (GAs) are an important group of hormones which exert various effects on promoter and regulator of plant growth. Gibberellic acid (GA(3)) is a natural plant hormone, with great economical and industrial importance. It affects stem elongation, germination, elimination of dormancy, flowering, sex expression, enzyme induction and leaf and fruit senescence. Despite its diverse applications, the use of GA(3) is limited due to its high production costs. The industrial process currently used for the production of GA(3) is based on submerged fermentation (SmF) techniques. As an alternative for its production, solid state fermentation (SSF) has also been investigated for its ability to increase the yields of GA(3) with the use of agro-industrial wastes as support/substrate, which contributes to the decreased production costs. This review describes GA(3)'s physical, chemical and biological properties, its production by fermentation and new advances that are being carried out with special interest on the SSF technique.

Transcriptional and Enzymatic Profiling of Pleurotus ostreatus Laccase Genes in Submerged and Solid-State Fermentation Cultures

Abstract: The genome of the white rot basidiomycete Pleurotus ostreatus includes 12 phenol oxidase (laccase) genes. In this study, we examined their expression profiles in different fungal strains under different culture conditions (submerged and solid cultures) and in the presence of a wheat straw extract, which was used as an inducer of the laccase gene family. We used a reverse transcription-quantitative PCR (RT-qPCR)-based approach and focused on determining the reaction parameters (in particular, the reference gene set for the normalization and reaction efficiency determinations) used to achieve an accurate estimation of the relative gene expression values. The results suggested that (i) laccase gene transcription is upregulated in the induced submerged fermentation (iSmF) cultures but downregulated in the solid fermentation (SSF) cultures, (ii) the Lacc2 and Lacc10 genes are the main sources of laccase activity in the iSmF cultures upon induction with water-soluble wheat straw extracts, and (iii) an additional, as-yet-uncharacterized activity (Unk1) is specifically induced in SSF cultures that complements the activity of Lacc2 and Lacc10. Moreover, both the enzymatic laccase activities and the Lacc gene family transcription profiles greatly differ between closely related strains. These differences can be targeted for biotechnological breeding programs for enzyme production in submerged fermentation reactors.

Production and Application of Xylanase from Penicillium sp. Utilizing Coffee By-products

Abstract: The lignocellulosic coffee by-products such as coffee pulp, coffee cherry husk, silver skin, and spent coffee were evaluated for their efficacy as a sole carbon sources for the production of xylanase in solid-state fermentation using Penicillium sp. CFR 303. Among the residues, coffee cherry husk was observed to produce maximum xylanase activity of 9,475 U/g. The process parameters such as moisture (50%), pH (5.0), temperature (30 °C), particle size (1.5 mm), inoculum size (20%), fermentation time (5 days), carbon source (xylose), and nitrogen source (peptone) were optimized and the enzyme activity was in the range of 19,560–20,388 U/g. The enzyme production was further improved to 23,494 U/g with steam as a pre-treatment. The extracellular xylanase from the fungal source was purified to homogeneity from culture supernatant by ammonium sulfate fractionation, DE32-cellulose with a recovery yield of 25.5%. It appeared as a single band on SDS-PAGE gel with a molecular mass of approximately 27 kDa. It had optimum parameters of 50 °C temperature, pH 5.0, K m 5.6 mg/mL, and V max 925 μmol mg−1 min−1 with brichwood xylan as a substrate. The crude enzyme hydrolysed lignocellulosic substrate as well as industrial pulp. Production of xylanase utilizing coffee by-products constitutes a renewable resource and is reported for the first time.

Optimization of Lignin Peroxidase, Manganese Peroxidase, and Lac Production from Ganoderma lucidum Under Solid State Fermentation of Pineapple Leaf

Abstract: This study was undertaken to isolate ligninase-producing white-rot fungi for use in the extraction of fibre from pineapple leaf agriwaste. Fifteen fungal strains were isolated from dead tree trunks and leaf litter. Ligninolytic enzymes (lignin peroxidase (LiP), manganese peroxidase (MnP), and laccase (Lac)), were produced by solid-state fermentation (SSF) using pineapple leaves as the substrate. Of the isolated strains, the one showing maximum production of ligninolytic enzymes was identified to be Ganoderma lucidum by 18S ribotyping. Single parameter optimization and response surface methodology of different process variables were carried out for enzyme production. Incubation period, agitation, and Tween-80 were identified to be the most significant variables through Plackett-Burman design. These variables were further optimized by Box-Behnken design. The overall maximum yield of ligninolytic enzymes was achieved by experimental analysis under these optimal conditions. Quantitative lignin analysis of pineapple leaves by Klason lignin method showed significant degradation of lignin by Ganoderma lucidum under SSF.

Polyphenolic Antioxidant Mobilization in Apple Pomace by Different Methods of Solid-State Fermentation and Evaluation of Its Antioxidant Activity

Abstract: An investigation was carried out to understand the changes and mobilization of polyphenolics and the improvement in their antioxidant properties in apple pomace by solid-state fermentation using Generally Recognized as Safe grade fungus, Phanerochaete chrysosporium, by different fermentation techniques, such as flask, tray, and fermentor. β-glucosidase, ligninolytic enzymes activity, and polyphenolic-linked antioxidant activity of apple pomace during solid-state fermentation was studied. During the course of solid-state fermentation, there was an increase in the extractable polyphenolic content (15.53 to 29.28 mg of gallic acid equivalents per gram of dry weight (DW)) on the 7th day followed by a decline in the polyphenol content. Antioxidant activity was measured by 1,1-diphenyl-2-picrylhydrazyl radical inhibition system, and the increase in activity (∼35%) was directly proportional to polyphenolic content over the course of solid-state fermentation. After an initial lag phase with little activity, the β-glucosidase activity increased by 6-, 7-, and 6-fold in flask (18.12 U/g DW samples), fermentor (44.52 U/g of DW sample), and tray fermentation (46.66 U/g DW sample) methods, respectively. Both polyphenolics and antioxidant capacity correlated with the increase in the β-glucosidase activity and showed that the enzyme played an important role in the release of polyphenolic aglycones from apple pomace and therefore increased the antioxidant capacity. In addition, ligninolytic enzymes showed a direct correlation with the mobilization and polymerization of polyphenolic content during the solid-state fermentation.