Biotechnological strategies to improve production of microbial poly-(3-hydroxybutyrate): a review of recent research work (original) (raw)
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Production of Polyhydroxybutyrate Using Bacterial Strains
2015
Polyhydroxybutyrate is a polyhydroxyalkanoate (PHA), a polymer having a place with the polyesters classes. That areinterest as biodegradable and bio-derived plastics. The poly-3-hydroxybutyrate (P3HB) sort of PHB ispresumably the most widely recognized sort of polyhydroxyalkanoate, yet different polymers of this class are created by a mixture of life forms: these incorporate poly-4-hydroxybutyrate (P4HB), polyhydroxyvalerate (PHV), polyhydroxyhexanoate (PHH), polyhydroxyoctanoate (PHO) and their copolymers.Synbiotic sachets were obtained from general medical store and Soil was gathered from garden and screened for PHB delivering microscopic organisms. A few unidentified bacterial colonies were confined utilizing serial dilation method. Every bacterial colony was kept up in slants and liquid cultures. A lab strain of Lactobacillus was refined and kinetic studies were performed. Lactobacillus acidophilus produced PHB.
Microbial polyhydroxybutyrate production by using cheap raw materials as substrates
Indian Journal of Pharmaceutical and Biological Research
Bioplastic, Polyhydroxybutyrate (PHB) is well known for it’s environmental friendliness and complete decomposition into water and carbon dioxide by microorganisms. The main drawback of PHB commercialization is it’s high production cost which is 10 times higher than that of synthetic plastic. So, the present research work mainly focussed on the fermentative production of PHB by Bacillus amyloliquifaciens and Nocardiopsis potens using low cost raw materials like Molasses, wheat bran, rice bran, ragi bran, jambul seed powder, orange peel and whey as substrates. Bacillus amyloliquifaciens and Nocardiopsis potens gives maximum PHB 16.5 µg/ ml and 26.8 µg/ ml respectively in the medium containing molasses and wheat bran as a substrates. Further the functional groups of extracted PHB were confirmed by Fourier transform infrared spectroscopy.
Polyhydroxyalkanoates (PHAs) are bacterial polymers that are formed as naturally occurring storage polyesters by a wide range of microorganisms. Biodegradable and biocompatible poly(3-hydroxybutyrate) (PHB) and its copolymers with 3-hydroxyvalerate (PHBV) are the best known representatives of PHA family. For more than 20 years biosynthesis, biodegradation and applications of PHB and its copolymers have been studied in the Bach Institute of Biochemistry RAS. An effective technology for production of PHB and PHBV of different molecular weight (from 200 to 1500 kDa) by diazotrophic bacteria of Azotobacter and Rhizobium genus has been developed. In order to clarify mechanism of PHB biodegradation degradation of PHB at different conditions in vitro and in vivo have been studied. A number of medical devices on basis of PHB: surgical meshes, screws and plates for bone fixation, periodontal membranes, and wound dressing are developed. High biocompatibility of PHB films and medical devices implanted in animal tissues has been demonstrated. Nowadays, development of systems of sustained drug delivery on the base of PHAs microspheres and microcapsules as a new and promising trend in the modern pharmacology is intensively in progress.
Poly-3-hydroxybutyrate production byAzotobacter chroococcum
Folia Microbiologica, 2001
Thirty-seven soil isolates and mutants of Azotobacter chroococcurn tested for poly-3-hydroxybutyrate (PHB) production using Sudan black B staining method were found to be positive. One mutant showed a higher number of PHB-producing ceils and maximum number of granules per cell. Using 2 % glucose and 15 mmol/L ammonium acetate, PHB production was found to be maximum at 36 and 48 h of growth under submerged cultivation and under stationary cultivation, respectively. PHB production was found to be higher on sucrose and commercial sugar (as carbon sources) as compared to glucose and mannitol. As commercial sugar is cheaper than sucrose it was selected as carbon source for PHB production, that being found to be maximum at 1% concentration. Inorganic nitrogen sources seemed to have no stimulatory effect on the production of PHB. However, ammonium acetate (15 retool/L) was found to be best for PHB production. Peptone (0.2 %) gave a better yield of PHB under both growth conditions. Using all optimized conditions, PHB production was studied in ten selected strains. Two of them were found to be best PHB producers under both growth conditions, one producing 621 and 740 ttg/g dry mass under submerged cultivation and under stationary cultivation, respectively, while the second one produced 589 and 733 pg/g. Plastic materials have become an integral part of contemporary life because of their many desirable properties including durability and resistance to degradation. When these polymers are discarded in nature, they can persist for many decades, at best a mere eyesore, at worst posing a threat to wildlife. Recently, the problems concerning global environment and solid waste management have generated much interest in the development of biodegradable plastics with desired physical and chemical properties of synthetic plastics. Polyhydroxyalkanoates (PHAs), most commonly represented by poly-3-hydroxybutyrate (PHB) are such biologically produced biodegradable plastics that have many of the general properties of synthetic plastics (Byrom I987) and can be synthesized by cells in various chemical forms. They are synthesized as intracellular carbon and energy compounds and accumulated as granules in the cytoplasm of cells. Organisms that have been used for PHB production are Alcaligenes eutrophus, A. latus, Pseudomonas spp., Bacillus spp., Azospirillum spp., Azotobacter spp., methylotrophs and recombinant Escherichia coli (see, e.g. Pal et al. 1998). The possibility of producing PHB in transgenic plants is also being studied by several researchers. Poly-3-hydroxybutyrate is found to possess various important properties including moisture resistance, piezoelectricity and optical purity besides having the most important property of biodegradability. The possible applications of PHB include packaging films, bags and containers as a biodegradable carrier for long-term dosage of drugs, medicines, disposable items in other medical areas, such as wound dressing and blood vessel replacements. Keeping in view the wide range of its applications, particularly in overcoming pollution, the biggest hazard of today, studies were undertaken with the objective to investigate PHB production in Azotobacter chroococcum and to find out the best possible physiological conditions for PHB production in A. chroococcum. MATERIALS AND METHODS Bacterial cultures. Thirty-seven soil isolates and mutants ofAzotobacter chroococcum used were procured from the culture collection,
Poly-β-hydroxybutyrate (PHB) is the intracellular lipid reserve accumulated by many bacteria. The most potent terrestrial bacterium Bacillus cereus SE-1 showed more PHB accumulating cells (22.1 and 40% after 48 and 72 h) than that of the marine Bacillus sp. CS-605 (5 and 33% after 48 and 72 h). Both the isolates harbored phbB gene and the characteristics C=O peak was observed in the extracted PHB by Fourier transformed infrared spectroscopy analysis. Maltose was found to be the most suitable carbon source for the accumulation of PHB in B. cereus SE-1. The extracted PHB sample from B. cereus SE-1 was blended with a thermoplastic starch (TS) and an increased thermoplasticity and decreased crystallinity were observed after blending in comparison to the standard PHB. The melting temperature (T m ), melting enthalpy (ΔHf), and crystallinity (X c ) of the blended PHB sample were found to be 109.4°C, 64.58 J/g, and 44.23%, respectively.
Polymers, 2022
In this work, the strains Bacillus megaterium BM 1, Azotobacter chrocococcumAz 3, Bacillus araybhattay RA 5 were used as an effective producer of poly-3-hydroxybutyrate P(3HB). The purpose of the study was to isolate and obtain an effective producer of P(3HB) isolated from regional chestnut soils of northern Kazakhstan. This study demonstrates the possibility of combining the protective system of cells to physical stress as a way to optimize the synthesis of PHA by strains. Molecular identification of strains and amplification of the phbC gene, transmission electron microscope (TEM), extracted and dried PHB were subjected to Fourier infrared transmission spectroscopy (FTIR). The melting point of the isolated P(3HB) was determined. The optimal concentration of bean broth for the synthesis of P(3HB) for the modified type of Bacillus megaterium RAZ 3 was 20 g/L, at which the dry weight of cells was 25.7 g/L−1 and P(3HB) yield of 13.83 g/L−1, while the percentage yield of P(3HB) was 53....
Polymers
Thirty bacterial isolates were tested on three different media for Poly-ß-hydroxybutyrate (PHB) production. The best bacterial isolates for producing PHB were screened and identified based on molecular biology; then, using three different alternative carbon sources (dried whey, sugar beet molasses and date molasses), physical properties were evaluated by Infrared (IR) spectrometry and Gas chromatography–mass spectrometry (GC-MS/MS) analysis. Our results showed that the best isolates identified based on molecular biology were Bacillus paramycoides MCCC 1A04098, Azotobacter salinestris NBRC 102611 and Brevundimonas naejangsanensis BIO-TAS2-2. The addition of sugar beet molasses to the medium of A. salinestris increased the cell dry weight (CDW), PHB concentration, PHB% and conversion coefficient (4.97 g/L, 1.56 g/L, 31.38% and 23.92%, respectively). The correlation coefficient values between PHB g/L and CDW g/L varied between very strong and moderate positive correlation. IR of the pr...
Bacterial Production of Poly-β-hydroxybutyrate (PHB): Converting Starch into Bioplastics
Bioplastics for Sustainable Development
Poly-β-hydroxybutyrate (PHB) is a thermoplastic polyester accumulated intracellularly by many microorganisms under unfavorable growth conditions. The features of PHB are biodegradable and biocompatible, and the physical properties are similar to polypropylene, which has attracted industrial attention as an environmentally degradable plastic for a wide range of agricultural, marine, and medical applications and appropriate substitutes for hydrocarbon-based plastics. Starch is a renewable carbon source from plant sources available abundantly in large quantities throughout the globe and has recently been used as a carbon source for PHB production. The utilization of starch in PHB production needs enzymatic hydrolysis for starch degradation since many microorganisms do not produce these enzymes natively. This suggests there is a need for exploitation of bacterial culture for the co-production of the starch-hydrolyzing enzyme (amylolytic bacteria) as well as PHB. Some bacteria have been reported capable to convert starch into PHB directly, which are from the genus Bacillus. The process of PHB production from starch by amylolytic bacteria is simultaneous saccharification and fermentation (SSF). The mechanism of bacteria synthesizing PHB from starch is divided into two groups, namely, the growth-associated PHB
Microbial production of polyhydroxybutyrate, a
2013
Plastics produced from petrochemical sources and known as polypropylene are now accumulating in our environment at rates of millions of tons per year creating severe problems. The present study aims to the production and isolation of PHB (polyhydroxy-buty rate), a biodegradable plastic, from agro-industrial waste products (whey and date molasses) due to its high economic and industrial importance , taking into consideration many points that lead to produce PHB on large scale. The methodology of this study includes screening study for the isolation of a promising microbial producer of PHB , and optimization experiments to evaluate the best environmental and physiological factors that lead to maximum PHB production. Under the optimized conditions, Lactobacillus acidophilus has shown maximum production when grown for 4 days on date molasses supplemented with NB yielding 0.412g/50ml of PHB, followed by Bacillus thuringiensis (0.367g/50ml) grown for 4 days on the same medium, and Bacillus subtilis (0.337g/50ml) grown for 6 days on whey supplemented with glucose, yeast extract, and peptone. Eleven nutritional factors were examined for their significance on PHB production using a statistical design known as Plackette-Burman. Maximum PHB output of 43.1 g/l produced by Lactobacillus acidophilus was revealed by the statistical design, which represents about 7.04 fold increase in PHB production. Fedbatch fermentation was carried out using the optimized fermentation medium and PHB production has been increased to 27.5% as compared with batch closed process. PHB was detected by transmission electron microscopy and monitoring UV spectra of the sample by scanning the samples between 220 and 300nm compared with standard PHB. Lactobacillus acidophilus can be used for PHB production on large industrial scale, solving by this one of the problems of solid waste management that results from the accumulation of plastics and saving the environment from additional air pollution caused by its recycling.