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Journal ArticleDOI

Production of PHB and P (3HB-co-3HV) biopolymers by Bacillus megaterium strain OU303A isolated from municipal sewage sludge

01 Mar 2009-World Journal of Microbiology & Biotechnology (Springer Netherlands)-Vol. 25, Iss: 3, pp 391-397
TL;DR: This is the first report of B. megaterium strain producing HV copolymer, without the addition of any precursor in the fermentation medium, and it is found that this strain was capable of producing 2.5% hydroxyvalerateCopolymer from a single carbon substrate, glucose.
Abstract: Bacillus megaterium strain OU303A isolated from municipal sewage sludge was selected for the study of biosynthesis of polyhydroxybutyrate (PHB) and polyhydroxybutyrate-co-hydroxyvalerate P (HB-co-HV) copolymer. The strain yielded a maximum of 62.43% DCW polymer in the medium containing glycerol as carbon source, which was followed by 58.63% DCW polymer in glucose containing medium. We found that this strain was capable of producing 2.5% hydroxyvalerate copolymer from a single carbon substrate, glucose. The strain showed an increase in the amount of HV monomer content, when the precursor for the copolymer was included in the fermentation medium. The characterization of the biopolymers was carried out using FTIR, GC-MS, H1 NMR and DSC. This is the first report of B. megaterium strain producing HV copolymer, without the addition of any precursor in the fermentation medium.
Citations
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Journal ArticleDOI
TL;DR: Bacillus can be considered the dark horse in the race to generate sustainable energy, ecofriendly non-fossil fuel-based polymers, and bioactive molecules for use as therapeutics.

200 citations


Additional excerpts

  • ...11 Reddy et al. (2009b)...

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  • ...7 Reddy et al. (2009a)...

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Journal ArticleDOI
TL;DR: The isolated Bacillus sp can be used for feasible production of PHB using agro-residues especially sugarcane bagasse which can reduce the production cost in addition to reducing the disposal problem of these substrates.
Abstract: Polyhydroxybutyrates (PHBs) are macromolecules synthesized by bacteria. They are inclusion bodies accumulated as reserve materials when the bacteria grow under different stress conditions. Because of their fast degradability under natural environmental conditions, PHBs are selected as alternatives for production of biodegradable plastics. The aim of this work was to isolate potential PHB producing bacteria, evaluate PHB production using agro-residues as carbon sources. Among fifty bacterial strains isolated from different localities, ten PHB accumulating strains were selected and compared for their ability to accumulate PHB granules inside their cells. Isolate Arba Minch Waste Water (AWW) identified as Bacillus spp was found to be the best producer. The optimum pH, temperature, and incubation period for best PHB production by the isolate were 7, 37 °C, and 48 h respectively at 150 rpm. PHB production was best with glucose as carbon source and peptone as nitrogen source. The strain was able to accumulate 55.6, 51.6, 37.4 and 25% PHB when pretreated sugar cane bagasse, corn cob, teff straw (Eragrostis tef) and banana peel were used as carbon sources respectively. Fourier transform-infrared authentication results of the extracted and purified PHB identified its functional units as C–H, CH2, C=O and C–O groups. UV–Vis spectrophotometric analysis and biodegradability test confirmed the similarity of the extract with standard PHB and its suitability for bioplastic production. The isolated Bacillus sp can be used for feasible production of PHB using agro-residues especially sugarcane bagasse which can reduce the production cost in addition to reducing the disposal problem of these substrates. The yield of PHB can further be boosted by optimization of production parameters as substrates.

188 citations


Additional excerpts

  • ...Bacillus sp are reported to be ideal PHB producers in many previous studies [17, 18]....

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Journal ArticleDOI
TL;DR: Two isolates, NAP11 and NAC1, were selected and classified up to genus level by studying their morphological and biochemical characteristics and were found to be Enterococcus sp.
Abstract: Background. Polyhydroxyalkanoates (PHAs) are storage materials that accumulate by various bacteria as energy and carbon reserve materials. They are biodegradable, environmentally friendly, and also biocompatible bioplastics. Unlike petrochemical-based plastics that take several decades to fully degrade, PHAs can be completely degraded within a year by variety of microorganisms into CO2 and water. In the present study, we aim to utilize pulp, paper, and cardboard industry sludge and waste water for the isolation and screening of polyhydroxyalkanoates (PHAs) accumulating bacteria and production of cost-effective PHB using cardboard industry waste water. Results. A total of 42 isolates showed black-blue coloration when stained with Sudan black B, a preliminary screening agent for lipophilic compounds, and a total of 15 isolates showed positive result with Nile blue A staining, a more specific dye for PHA granules. The isolates NAP11 and NAC1 showed maximum PHA production 79.27% and 77.63% with polymer concentration of 5.236 g/L and 4.042 g/L with cardboard industry waste water. Both of the selected isolates, NAP11 and NAC1, were classified up to genus level by studying their morphological and biochemical characteristics and were found to be Enterococcus sp., Brevundimonas sp. and, respectively. Conclusion. The isolates Enterococcus sp. NAP11 and Brevundimonas sp. NAC1 can be considered as good candidates for industrial production of PHB from cardboard industry waste water. We are reporting for the first time the use of cardboard industry waste water as a cultivation medium for the PHB production.

145 citations

Journal ArticleDOI
20 Sep 2012-PLOS ONE
TL;DR: The biosynthesis and characterization of medium chain length poly-3-hydroxyalkanoates (mcl-PHA) produced by Pseudomonas putida Bet001 isolated from palm oil mill effluent was studied and showed semi-crystalline polymer with good thermal stability.
Abstract: The biosynthesis and characterization of medium chain length poly-3-hydroxyalkanoates (mcl-PHA) produced by Pseudomonas putida Bet001 isolated from palm oil mill effluent was studied. The biosynthesis of mcl-PHA in this newly isolated microorganism follows a growth-associated trend. Mcl-PHA accumulation ranging from 49.7 to 68.9% on cell dry weight (CDW) basis were observed when fatty acids ranging from octanoic acid (C8:0) to oleic acid (C18:1) were used as sole carbon and energy source. Molecular weight of the polymer was found to be ranging from 55.7 to 77.7 kDa. Depending on the type of fatty acid used, the 1 H NMR and GCMSMS analyses of the chiral polymer showed a composition of even and odd carbon atom chain with monomer length of C4 to C14 with C8 and C10 as the principal monomers. No unsaturated monomer was detected. Thermo-chemical analyses showed the accumulated PHA to be semi-crystalline polymer with good thermal stability, having a thermal degradation temperature (Td) of 264.6 to 318.8 (60.2) o C, melting temperature (Tm) of 43. (60.2) o C, glass transition temperature (Tg )o f21.0 (60.2) o C and apparent melting enthalpy of fusion (DHf) of 100.9 (60.1) J g 21 .

124 citations


Cites background from "Production of PHB and P (3HB-co-3HV..."

  • ...2), where 99% analogy was observed between the isolate and Pseudomonas putida strains AJ785569, AN2, BCNU106, DQ060242 and DQ087528....

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  • ...Among the extensively studied bacterial species are those belonging to genus Pseudomonas [9,10,11,12,13], that are known to accumulate intracellular PHA under limited cell growth phase in the presence of abundant carbon source and minimal nutrient condition [14]....

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  • ...The biochemical analyses indicated a probability of 99.5% for the isolate to be identified as Pseudomonas putida....

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  • ...The biosynthesis and characterization of medium chain length poly-3-hydroxyalkanoates (mcl-PHA) produced by Pseudomonas putida Bet001 isolated from palm oil mill effluent was studied....

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  • ...This observation was found to be in good agreement with what has been reported by Matsusaki et al. [32] when observing the PHA biosynthesis in recombinant Pseudomonas sp. 6 1–3 strain fed with dodecanoic acid (C12:0)....

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Journal ArticleDOI
TL;DR: This is the first report demonstrating the abilities of B. thuringiensis to convert CG into PHA co-polymer under non-limiting N conditions.

107 citations

References
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Journal ArticleDOI
TL;DR: The physiological functions of PHB as a reserve material and in symbiotic nitrogen fixation and its presence in bacterial plasma membranes and putative role in transformability and calcium signaling are also considered.

2,654 citations

Journal ArticleDOI
TL;DR: An overview of the different PHA biosynthetic systems and their genetic background is provided, followed by a detailed summation of how this natural diversity is being used to develop commercially attractive, recombinant processes for the large-scale production of PHAs.
Abstract: Poly(3-hydroxyalkanoates) (PHAs) are a class of microbially produced polyesters that have potential applications as conventional plastics, specifically thermoplastic elastomers. A wealth of biological diversity in PHA formation exists, with at least 100 different PHA constituents and at least five different dedicated PHA biosynthetic pathways. This diversity, in combination with classical microbial physiology and modern molecular biology, has now opened up this area for genetic and metabolic engineering to develop optimal PHA-producing organisms. Commercial processes for PHA production were initially developed by W. R. Grace in the 1960s and later developed by Imperial Chemical Industries, Ltd., in the United Kingdom in the 1970s and 1980s. Since the early 1990s, Metabolix Inc. and Monsanto have been the driving forces behind the commercial exploitation of PHA polymers in the United States. The gram-negative bacterium Ralstonia eutropha, formerly known as Alcaligenes eutrophus, has generally been used as the production organism of choice, and intracellular accumulation of PHA of over 90% of the cell dry weight have been reported. The advent of molecular biological techniques and a developing environmental awareness initiated a renewed scientific interest in PHAs, and the biosynthetic machinery for PHA metabolism has been studied in great detail over the last two decades. Because the structure and monomeric composition of PHAs determine the applications for each type of polymer, a variety of polymers have been synthesized by cofeeding of various substrates or by metabolic engineering of the production organism. Classical microbiology and modern molecular bacterial physiology have been brought together to decipher the intricacies of PHA metabolism both for production purposes and for the unraveling of the natural role of PHAs. This review provides an overview of the different PHA biosynthetic systems and their genetic background, followed by a detailed summation of how this natural diversity is being used to develop commercially attractive, recombinant processes for the large-scale production of PHAs.

1,540 citations

Book ChapterDOI
TL;DR: The chapter considers the evidence for the energy-storage roles of glycogen, polyphosphates and poly-p-hydroxybutyrate, and the current state of knowledge concerning the regulation of their biosynthesis and degradation in the microbial cell.
Abstract: Publisher Summary This chapter focuses on the polymeric reserve materials and thus excludes the consideration of lipids other than poly-β-hydroxybutyrate, and the disaccharide trehalose, which plays an important role in the economy of the yeast cell, but displays certain features that are at variance with the normally accepted behavior of storage compounds. The chapter considers the evidence for the energy-storage roles of glycogen, polyphosphates and poly-p-hydroxybutyrate, and the current state of knowledge concerning the regulation of their biosynthesis and degradation in the microbial cell. The intracellular location of the enzymes concerned with polymer synthesis and degradation is an intriguing problem. The most detailed work has been carried out with PHB granules, which have PHB synthetase and a factor involved in depolymerase activity associated with the membrane that bounds the granule. The depolymerase system is a complex one that also involves a soluble fraction, underlining the importance of reactions at liquid-solid interfaces in the process and emphasizing that relatively little work has been done to isolate polyphosphate or glycogen granules in their native state in order to examine the possibility of regulation by a membranous system.

829 citations

Journal ArticleDOI
TL;DR: It is shown that the intermediate 3-Hydroxy fatty acids can also be polymerized to intracellular poly-(R)-3-hydroxyalkanoates (PHAs) when the medium contains limiting amounts of essential elements, such as nitrogen.
Abstract: Pseudomonas oleovorans grows on C(6) to C(12)n-alkanes and 1-alkenes. These substrates are oxidized to the corresponding fatty acids, which are oxidized further via the beta-oxidation pathway, yielding shorter fatty acids which have lost one or more C(2) units. P. oleovorans normally utilizes beta-oxidation pathway intermediates for growth, but in this paper we show that the intermediate 3-hydroxy fatty acids can also be polymerized to intracellular poly-(R)-3-hydroxyalkanoates (PHAs) when the medium contains limiting amounts of essential elements, such as nitrogen. The monomer composition of these polyesters is a reflection of the substrates used for growth of P. oleovorans. The largest monomer found in PHAs always contained as many C atoms as did the n-alkane used as a substrate. Monomers which were shorter by one or more C(2) units were also observed. Thus, for C-even substrates, only C-even monomers were found, the smallest being (R)-3-hydroxyhexanoate. For C-odd substrates, only C-odd monomers were found, with (R)-3-hydroxyheptanoate as the smallest monomer. 1-Alkenes were also incorporated into PHAs, albeit less efficiently and with lower yields than n-alkanes. These PHAs contained both saturated and unsaturated monomers, apparently because the 1-alkene substrates could be oxidized to carboxylic acids at either the saturated or the unsaturated ends. Up to 55% of the PHA monomers contained terminal double bonds when P. oleovorans was grown on 1-alkenes. The degree of unsaturation of PHAs could be modulated by varying the ratio of alkenes to alkanes in the growth medium. Since 1-alkenes were also shortened before being polymerized, as was the case for n-alkanes, copolymers which varied with respect to both monomer chain length and the percentage of terminal double bonds were formed during nitrogen-limited growth of P. oleovorans on 1-alkenes. Such polymers are expected to be useful for future chemical modifications.

714 citations