Production Of Biodegradable Polymers Research Articles

Kinetics and synthesis of poly(3-hydroxybutyrate) by a putative-mutant of Bacillus licheniformis

The present study deals with the kinetics of improved poly(3-hydroxybutyrate) (PHB) production by an L-cysteine HCl-depressed mutant of Bacillus licheniformis. Production of biodegradable polymers is to eliminate use of materials derived from petrochemicals and also because of their environmental impact. For the current study, mutant strain (NA-21) & wild-type (IIB-isl19) were used for PHB production. Submerged culture with two-stage fermentation technique was used for PHB production. Results indicated that PHB production was improved with 300 mM of –HNO2. The superior mutant strain (NA-21) resulted in 2-fold more PHB as compared to the wild-type (IIB-isl9). It was selected, and resistance against L-cysteine HCl was developed. At 4 ppm concentration of L-cysteine HCl, PHB production by mutant strain (NA-cys4) was higher than its wild counterpart by 5.7-fold. Kinetic study of parameters including specific growth rate (µ h− 1), growth (Yx/s,Ys/x), product yield coefficients (Yp/s,Yp/x), volumetric rate constants (Qp, Qs, Qx) and specific rate constants (qp, qs, qx), were also accomplished. Moreover, Yp/x, Qp and qp = µ × Yp/x were found to be very significant as 1.254 ± 0.06 (g/g biomass), 0.134 ± 0.01 (g/l/h) and 0.168 ± 0.01 (g/g/h), respectively. The effect of fatty acids on PHB production highlighted the improvement in PHB production by 1.94-fold. The highest PHB production during the study was 16.35 ± 3.12 g/l which highlighted its significance (p ≤ 0.05) and impact on the overall process. The variation in PBH yield between wild-type and mutant B. licheniformis is possibly because of induced DNA interstrand thus making unstable thymidine-thymidine dymers. From the results, it was concluded that improved PHB production on industrial scale is fairly possible and it holds the potential to contribute significantly to plastic circularity in the future.

Polyhydroxybutyrate synthesis in Camelina: Towards coproduction of renewable feedstocks for bioplastics and fuels.

Plant-based co-production of polyhydroxyalkanoates (PHAs) and seed oil has the potential to create a viable domestic source of feedstocks for renewable fuels and plastics. PHAs, a class of biodegradable polyesters, can replace conventional plastics in many applications while providing full degradation in all biologically active environments. Here we report the production of the PHA poly[(R)-3-hydroxybutyrate] (PHB) in the seed cytosol of the emerging bioenergy crop Camelina sativa engineered with a bacterial PHB biosynthetic pathway. Two approaches were used: cytosolic localization of all three enzymes of the PHB pathway in the seed, or localization of the first two enzymes of the pathway in the cytosol and anchoring of the third enzyme required for polymerization to the cytosolic face of the endoplasmic reticulum (ER). The ER-targeted approach was found to provide more stable polymer production with PHB levels up to 10.2% of the mature seed weight achieved in seeds with good viability. These results mark a significant step forward towards engineering lines for commercial use. Plant-based PHA production would enable a direct link between low-cost large-scale agricultural production of biodegradable polymers and seed oil with the global plastics and renewable fuels markets.

Grape Stalk Valorization: An Efficient Re-Use of Lignocellulosic Biomass through Hydrolysis and Fermentation to Produce Lactic Acid from Lactobacillus rhamnosus IMC501

Lactobacillus rhamnosus is a homofermentative probiotic strain that was previously demonstrated to grow on lignocellulosic-derived raw materials and to convert glucose into L-lactic acid (LA) with yields that vary between 0.38 and 0.97 g/g. Lactic acid is a key platform chemical, largely applied in different biotechnological fields (spanning from the pharmaceutical to the food sector) and also as a building block for the production of biodegradable polymers. In the present study, grape stalks were evaluated as sources of fermentable sugars for the growth of L. rhamnosus IMC501 and for the production of LA, since millions of hectoliters of wine are produced every year worldwide, generating a huge amount of waste. Although grape stalks are quite recalcitrant, the combination of a steam explosion pre-treatment with optimized two-step hydrolysis and commercial enzymes (Cellic-CTec2) allowed us to obtain a cellulose conversion efficiency of about 37% and to develop small-scale 2 L batch fermentation processes. Results successfully demonstrate that L. rhamnosus IMC501 can tolerate biomass-derived inhibitors and grow on grape stalk hydrolysate without the need for additional sources of nitrogen or other nutritional elements, and that the strain can convert all glucose present in the medium into LA, reaching the maximal theoretical yield.

Making Persistent Plastics Degradable.

The vastness of the scale of the plastic waste problem will require a variety of strategies and technologies to move toward sustainable and circular materials. One of these strategies to address the challenge of persistent fossil-based plastics is new catalytic processes that are being developed to convert recalcitrant waste such as polyethylene to produce propylene, which can be an important precursor of high-performance polymers that can be designed to biodegrade or to degrade on demand. Remarkably, this process also enables the production of biodegradable polymers using renewable raw materials. In this Perspective, current catalyst systems and strategies that enable the catalytic degradation of polyethylene to propylene are presented. In addition, concepts for using "green" propylene as a raw material to produce compostable polymers is also discussed.

Electrocatalytic Upcycling of Biomass and Plastic Wastes to Biodegradable Polymer Monomers and Hydrogen Fuel at High Current Densities.

Transformation of biomass and plastic wastes to value-added chemicals and fuels is considered an upcycling process that is beneficial to resource utilization. Electrocatalysis offers a sustainable approach; however, it remains a huge challenge to increase the current density and deliver market-demanded chemicals with high selectivity. Herein, we demonstrate an electrocatalytic strategy for upcycling glycerol (from biodiesel byproduct) to lactic acid and ethylene glycol (from polyethylene terephthalate waste) to glycolic acid, with both products being as valuable monomers for biodegradable polymer production. By using a nickel hydroxide-supported gold electrocatalyst (Au/Ni(OH)2), we achieve high selectivities of lactic acid and glycolic acid (77 and 91%, respectively) with high current densities at moderate potentials (317.7 mA/cm2 at 0.95 V vs RHE and 326.2 mA/cm2 at 1.15 V vs RHE, respectively). We reveal that glycerol and ethylene glycol can be enriched at the Au/Ni(OH)2 interface through their adjacent hydroxyl groups, substantially increasing local concentrations and thus high current densities. As a proof of concept, we employed a membrane-free flow electrolyzer for upcycling triglyceride and PET bottles, attaining 11.2 g of lactic acid coupled with 9.3 L of H2 and 13.7 g of glycolic acid coupled with 9.4 L of H2, respectively, revealing the potential of coproduction of valuable chemicals and H2 fuel from wastes in a sustainable fashion.

Optimal Integrated Plant for Biodegradable Polymer Production.

An integrated facility for the production of biodegradable polymers from biomass residues has been developed. Lignocellulosic residues (sawdust), CO2, and organic waste such as manure or sludge are the raw materials. Manure and sludge are digested to provide the nutrients needed to grow algae. Algae are used in full to oil and starch production. The oil is transesterified with methanol generated via biogas dry reforming to obtain biodiesel and glycerol. The starch is used together with glycerol and the pretreated sawdust for the production of the biodegradable polymer. A mathematical optimization approach is used to identify the best use of each resource and the optimal operation of the integrated facility for each case. 4732 kt/yr of manure or 4653 kt/yr of sludge was processed to produce 354 kt/yr of biopolymer and 84 Mgal/yr of fatty acid methyl ester, capturing 2.47 kg of CO2 per kg of biopolymer with production costs of 0.89 and 0.95 $/kg, respectively, and an investment capital of 717 and 712 M$, respectively.

Optimization of Methane Feed and N:C Ratio for Biomass and Polyhydroxybutyrate Production by the Alphaproteobacterial Methanotroph Methylocystis sp. Rockwell

The consumption of methane and the production of biodegradable polymers using alphaproteobacterial methanotrophs offers a promising strategy to mitigate greenhouse gas emissions and reduce non-biodegradable plastic pollution. This study identified an ideal amount of added methane and N:C ratio in 100 mL batch cultures of the alphaproteobacterial methanotroph Methylocystis sp. Rockwell growing in 1-L sealed bottles using Response Surface Methodology (RSM) to achieve both high biomass and high polyhydroxybutyrate (PHB) production. RSM analysis showed achievement of optimal biomass at 474.7 ± 10.1 mg/L in nitrate mineral salts (NMS) medium and 480.0 ± 65.5 mg/L biomass in ammonium mineral salts (AMS) medium with 8 mmol of methane and an N:C ratio of 0.022. However, optimal PHB concentration was achieved with 6 mmol methane at N:C ratios of 0.012 in NMS medium (149.7 ± 16.1 mg/L) and 0.022 in AMS medium (200.3 ± 5.1 mg/L). A multi-objective RSM analysis projected maxima in PHB production and %PHB cell content (based on dry weight) when using 4.88 mmol methane and N:C ratio of 0.016 in NMS cultures, and 6.28 mmol methane and the 0.016 N:C ratio in AMS cultures. Cultures grown under these projected conditions produced 173.7 mg PHB/L with 46.8% PHB cell content in NMS and 196.9 mg/L with 53.1% PHB cell content in AMS. Taken together, these analyses predicted the optimal conditions for growth and PHB production in batch cultures of Methylocystis sp. Rockwell and confirmed a preference for ammonium as the N-source for PHB production. This information is valuable for media formulation in industrial scale-up of Methylocystis sp. Rockwell in PHB production.

A Stable and Reusable Supported Copper Catalyst for the Selective Liquid-Phase Hydrogenation of 5-Hydroxymethylfurfural to 2,5-Bis(hydroxymethyl)furan

Synthesis of 2,5-bis(hydroxymethyl)furan (BHMF) by selective 5-hydroxymethylfurfural (HMF) hydrogenation is ecofriendly and industrially important since HMF is obtained from renewable sources, and BHMF is a raw material used for production of biodegradable polymers. Four copper-based catalysts were prepared by incipient wetness impregnation (Cu/SiO2-I, Cu/Al2O3-I), precipitation–deposition (Cu/SiO2-PD) and coprecipitation (CuMgAl), and then tested in the liquid-phase hydrogenation of HMF. Metallic phases with large copper particles were obtained by incipient wetness impregnation, while precipitation methods gave highly dispersed metal copper nanoparticles. The pattern found for the concentration and strength of surface acid sites was: CuMgAl > Cu/Al2O3-I > Cu/SiO2-PD > Cu/SiO2-I. The copper-based catalysts active in HMF hydrogenation are all highly selective to BHMF, but the intrinsic activity and stability depend on metallic copper dispersion and support nature. The catalyst stability becomes poorer in the cases that the metallic phase is formed by large copper particles or interacts with high-acidity supports. Therefore, the catalyst with the highest activity, BHMF yield and stability was Cu/SiO2-PD. Furthermore, it was found that Cu/SiO2-PD is reusable in the selective liquid-phase HMF hydrogenation after being submitted to a two-step thermal treatment: (1) calcination under air flow at 673 K; (2) reduction under H2 flow at 523 K.

Langmuir monolayers as models of the lipid matrix of cyanobacterial thylakoid membranes

Cyanobacteria are omnipresent photosynthetic microorganisms that are crucial for the proper functioning of multiple environmental niches. Recently, these organisms have found various applications in soil remediation, waste utilization, and the production of biodegradable polymers. A significant volume of the cyanobacterial cell is occupied by thylakoid membranes, where the photosynthesis process is localized. These membranes are inhomogeneous and highly compartmentalized; however, the stimuli and forces leading to such a high degree of self-organization are not entirely understood. In our study, we apply Langmuir monolayers formed by the main lipids of cyanobacterial membranes: monogalactosyldiacylglycerol (MGDG), digalactosyldiacylglycerol (DGDG), sulfoquinovosyldiacylglycerol (SQDG), and phosphatidylglycerol (PG), as versatile models of thylakoid membranes. Special attention was paid to the binary system formed by the two neutral glycolipids MGDG and DGDG, as these two substances are most abundant in the membrane. Then the effects implied by the incorporation of anionic lipids were investigated. The morphology of the monolayers was studied by Brewster angle microscopy, while the ordering of the monolayer-forming molecules on the molecular scale was investigated with the Grazing incidence X-ray diffraction technique. It was proved that the inhomogeneous structure of cyanobacterial membrane is an intrinsic property of the applied structural lipids. It was also proved that the increase in anionic lipid content, frequently applied by cyanobacteria as a response to unfavorable environmental conditions, leads to significant changes in the morphology of the model membranes.

Tandem production of high-purity sodium glycolate via the dual purification technology of crystallization and active carbon adsorption

High-purity glycolic acid (GA) are highly required for the production of biodegradable polymers, pharmaceuticals, and fine chemicals. For production of bio-polyester, GA purity has emerged as a bottleneck. In this paper, we innovatively propose crystallization to dispose of purity problem and investigated the repurification of sodium glycolate crystals. Compared to traditional chemical techniques, resting cell catalysis with bio-oxidation of ethylene glycol (EG) is a promising method for the green industrial production of GA. Gluconobacter oxydans is one of the most promising strains because of its ability to ferment high GA titer from EG. However, the GA directly from fermentation broth does not meet the high purity requirements for biodegradable materials. Therefore, a tandem process was designed and experimentally verified by combining crystallization and active carbon (AC) adsorption. Sodium glycolate (SG) formation was adopted due to low-cost operation in the biological step and easy electrodialysis of GA. According to the dissociation constants (Kɑ) of glycolate, the fermentation broth was adjusted to pH 9.50 and SG saturates at 60 ℃ for SG crystallization. The macroscopic yellow plate-like crystals 91.1 g of SG with 94 % purity were produced at room temperature (25℃). In the tandem process, AC rapidly removed most pigment-like contaminants in the fermentation broth but adsorbed only a little SG (1 %), indicating selective and effective adsorption. Over 97 % of the color was removed by adding 8 % AC to a saturated solution (188 g/L). Finally, 79.2 g SG with 99 % purity was obtained at the yield of 87 % from 104 g/L SG broth. This tandem process could provide an economically-feasible approach for the industrial bioproduction of high-purity SG and GA derived from EG.

Facile Fabrication of Lignin-Cellulose Green Nanogels.

There has been increasing exploration of the development and production of biodegradable polymers in response to issues with petrol-based polymers and their impact on the environment. Here we report a new approach to synthesize a natural nanogel from lignin and nanocellulose. First, lignin nanobeads were synthesized by a solvent-shifting method, which showed a spherical shape with a diameter of 159.7 nm. Then the lignin nanobeads were incorporated into a nanocellulose network to form the lignin/cellulose nanogels. The nanocellulose fibrils (CNF-C) nanogels reveal a higher storage modulus than the nanocellulose crystal (CNC-C) ones due to the denser network with self-entanglement of longer cellulose chains. The presence of lignin nanobeads in the nanogels helped to increase the viscoelasticity of the nanogels. This work highlights that the new kinds of green nanogels could be potentially utilized in a variety of biomedical applications such as drug delivery and wound dressing.

Bioplastics / Biopolymers: How Aware Are We?

Today, polymers have found a wide range of uses from kitchen utensils to artificial heart valves, thanks to their lightness, easy shaping, corrosion resistance, and cheapness. A large number of polymers are used in the packaging of food, textiles, and machinery, and they are an important part of solid waste disposed of in landfills. In addition, microplastics, which are small particles under 5 mm, pose a major problem in the pollution of rivers, lakes, seas, and oceans and increase our carbon footprint. Many strategies are being developed in parallel with the Green Deal to reduce both all the negative effects caused by polymers and our carbon footprint. According to the European Green Deal, reducing waste, compensating for carbon footprint emissions, and protecting resources and sustainability are key priorities for the EU now and in the future. Reusability and biodegradable polymer production are important parts of these strategies. The scientific works demonstrated the opportunity for renewable, biodegradable biopolymers to replace their synthetic counterparts in a variety of /application. Biopolymer is a type of polymer and a biodegradable chemical compound that is produced by living beings in the ecosphere. Biopolymers obtained from natural materials (e.g. alginate, zein, gelatin, agar, and chitin/chitosan) are highly abundant but underexploited renewable biomasses. Besides their natural biological and structural functions, the biopolymers can be tailored to new biomaterials with novel functionalities. The roles of biopolymers in obtaining environmentally friendly materials are very important for the future of the world. 
 So, are we aware of plastic pollution and ways to reduce it? Is there enough awareness in academia, industry, and society for biopolymers that are so important for a sustainable environment? In this study, the answers to these questions are researched and discussed.

Sustainable Production of the Cyanophycin Biopolymer in Tobacco in the Greenhouse and Field.

The production of biodegradable polymers as coproducts of other commercially relevant plant components can be a sustainable strategy to decrease the carbon footprint and increase the commercial value of a plant. The biodegradable polymer cyanophycin granular polypeptide (CGP) was expressed in the leaves of a commercial tobacco variety, whose seeds can serve as a source for biofuel and feed. In T0 generation in the greenhouse, up to 11% of the leaf dry weight corresponded to the CGP. In T1 generation, the maximum content decreased to approximately 4% dw, both in the greenhouse and first field trial. In the field, a maximum harvest of 4 g CGP/plant could be obtained. Independent of the CGP content, most transgenic plants exhibited a slight yield penalty in the leaf biomass, especially under stress conditions in greenhouse and field trials. After the harvest, the leaves were either Sun dried or ensiled. The resulting material was used to evaluate the extraction of CGP compared to that in the laboratory protocol. The farm-level analysis indicates that the extraction of CGP from tobacco plants can provide alternative income opportunities for tobacco farmers. The CGP yield/ha indicates that the CGP production in plants can be economically feasible depending on the cultivation and extraction costs. Moreover, we analyzed the consumer acceptance of potential applications associated with GM tobacco in four European countries (Germany, Finland, Italy and the Netherlands) and found unexpectedly high acceptance.

Synthetic Celluloses as Green Fillers for the Enhancement of the Crystallization and Mechanical Properties of Poly(3-hydroxybutyrate-co-3-hydroxyvalerate)

Enzymatically synthetic cellulose is a novel green filler combining the advantage of degradability and environmental friendliness. In this work, poly(3-hydroxybutyrate-co-3-hydroxyvalerate) [P(HB-co-HV)] nanocomposites were fabricated using the melt blending technique through the addition of slatted cellulose (SC) or disc-shaped cellulose (DC). The effects of different morphologies and weight contents of cellulose on the crystallization behavior, morphology, and interaction of P(HB-co-HV) nanocomposites were investigated and analyzed. Compared with neat P(HB-co-HV), the yield strength and elongation at break of P(HB-co-HV)/0.1 wt %-SC nanocomposites were increased by 29 and 79%, respectively, while those for P(HB-co-HV)/0.5 wt %-DC nanocomposites were increased by 34 and 59%, respectively. Differential scanning calorimetry and polarized optical microscopy results demonstrated that cellulose increased the crystallization temperature and decreased the spherulite size of P(HB-co-HV). Wide-angle X-ray diffraction results illustrated that the growth of the grain and crystal plane was affected by cellulose. Fourier transform infrared spectroscopy results indicated that strong hydrogen bonds were formed at the interface between P(HB-co-HV) and cellulose. Scanning electron microscopy images revealed the uniform dispersion of cellulose in the polymer matrix. This study entails considerable advantages for the preparation of green nanofillers and the production of biodegradable polymers with excellent mechanical properties for tissue engineering in the presence of small amounts of fillers.

Optimization of Lactic Acid Production from Pineapple By-Products and an Inexpensive Nitrogen Source Using Lactiplantibacillus plantarum strain 4O8.

Lactic acid (LA) is used in food, cosmetic, chemical, and pharmaceutical industries and has recently attracted much attention in the production of biodegradable polymers. The expensive substances including carbon and nitrogen sources involved in its fermentative synthesis and the increasing market demand of LA have prompted scientists to look for inexpensive raw materials from which it can be produced. This research was aimed at determining the optimum conditions of lactic acid (LA) production from pineapple by-products and an inexpensive nitrogen source using Lactiplantibacillus plantarum strain 4O8. After collection and preparation of the carbon source (pineapple by-products) and nitrogen sources (by-products from fish, chicken, and beer brewing industries), they were used for the formulation of 4 different media in terms of nitrogen sources. Then, the proximate compositions of promising nitrogen sources were determined. This was followed by the screening of factors (temperature, carbon source, nitrogen source, MgSO4, MnSO4, FeSO4, KH2PO4, and KHPO4) influencing the production of LA using the definitive plan. Lastly, the optimization process was done using the central composite design. The highest LA productions (14.64 ± 0.05 g/l and 13.4 ± 0.02 g/l) were obtained in production medium supplemented with chicken and fish by-products, respectively, making them the most promising sources of nitrogen. The proximate analysis of these nitrogen sources revealed that their protein contents were 83.00 ± 1.41% DM and 74.00 ± 1.41% DM for chicken by-products and fish by-products, respectively. Concerning the screening of factors, temperature, nitrogen source, and carbon source were the factors that showed a major impact on LA production in the production medium containing chicken by-products as nitrogen source. A pineapple by-product concentration of 141.75 g/l, a nitrogen source volume of 108.99 ml/l, and a temperature of 30.89°C were recorded as the optimum conditions for LA production. The optimization led to a 2.73-fold increase in LA production when compared with the production medium without nitrogen source. According to these results, chicken by-products are a promising and an inexpensive nitrogen source that can be an alternative to yeast extract in lactic acid production.

ISOLATION OF SEAWEED ASSOCIATED BACTERIA'S AND THEIR PRODUCTION OF BIOPOLYMER BY SOLID-STATE FERMENTATION

Plastic material is any of a wide range of synthetic or semi-synthetic organic solids that are moldable. Plastics are typically organic polymers of high molecular mass, but they often contain other substances. They are usually synthetic, most commonly derived from petrochemicals, but many are partially natural. Environmental pollution by the disposal of non-degradable conventional plastics is a fast-growing problem worldwide, especially in India. Nowadays, plastics are replacing by other constructional materials like glass, wood, metal in numerous applications. In this study, there has been considerable interest in the development and production of biodegradable polymer to solve the current problem of pollution caused by the continuous use of synthetic polymer from seaweed associated Bactria. . Based on the dry weight of total biopolymer content, the strain SBT 09 showed maximum accumulation and selected for optimizing at different pH, temperature, salinity, carbon, and nitrogen source and the peak time of PHB accumulation. Based on the biochemical tests, the strain SBT 09 was found.The optimum pH, temperature, and salinity were found to be 7, 300C, and 5%. The peak time of PHB accumulation was found to be 36hrs. The best carbon and nitrogen source was found to be sucrose and (NH4)2 HPO4. The selected strain was mass cultured using the optimized media and PHB was extracted by solvent extraction. Keywords: Marine Bacteria, PHB, Biosynthesis, Biopolymer.

Biodegradable poly(butylene adipate-co-terephthalate) (PBAT)

Abstract Poly(butylene adipate-co-terephthalate), PBAT, is a synthetic and 100% biodegradable polymer based on fossil resources. Most conventional plastics utilized today are produced from petroleum-based products, making them nondecomposable. With polymer manufacturing companies under constant scrutiny due to the effect nondegradable plastics have on the environment, biodegradable polymer production is growing at an exponential rate. However, developing new biodegradable polymers that can maintain the requirements of expected material properties has been a challenge for material manufacturers. When compared to other polymers, PBAT is classified as polyester. Aliphatic polyesters biodegrade efficiently because of ester bonds in the soft chain portion of the polymer. These ester bonds are broken down through hydrolysis, making the polymer degradable in almost any environment. In this chapter, key components of biodegradable PBAT and prominent blends of PBAT will be reviewed and analyzed for suitable end-use applications. This chapter will also provide a general understanding of the chemical composition of PBAT and how the addition of components effect the properties of the material.

Transglutaminase Crosslinked Gelatin Films Extracted from Tanned Leather Waste

The production of biodegradable polymers has proved to be a promising alternative, since these materials have accelerated degradation, contributing to the reduction of residues and the reduction of environmental pollution. The tannery wastes contain considerable collagen and can be used for gelatin extraction and film production for use in agriculture. Gelatin-based films, however, present some challenges for practical application, such as permeability and solubility in water, parameters that can be improved through the crosslinking process by employing enzymes, promoting the union of polymeric gelatin chains. In this context, the action of the enzyme transglutaminase was investigated to improve the properties of gelatin films recovered from leather and chitosan residues, which were evaluated according to thickness, solubility, permeability, mechanical properties, and soil degradation. The results indicated that the enzyme concentration in the films had a significant effect on the properties of water permeability and solubility and strain to rupture. The evaluation of soil degradation showed that films with higher enzyme addition took longer to be degraded.

Model-based Optimization of Biopolymer Production from Glycerol

The present study focuses on sustainable production of biodegradable polymers by <br /> Cupriavidus necator DSMZ 545 using glycerol as substrate. The batch growth and biopolymer production kinetics were established in a 7-L bioreactor, which resulted in a <br /> total biomass of 8.88 g L–1 and poly(3-hydroxybutyrate) (PHB) accumulation of 6.76 g L–1. The batch kinetic and independently acquired substrate inhibition data were then used to develop a mathematical model for PHB production process. This was eventually used to design different nutrient feeding strategies under constant feed rate, decreasing feed rate, and pseudo steady state of substrate (glycerol) to optimize the PHB production during fed-batch cultivation. Among all the fed-batch cultivation strategies, the highest PHB accumulation and productivity of 13.12 g L–1 and 0.27 g L–1 h–1, respectively, was <br /> achieved in fed-batch bioreactor cultivation where a pseudo steady state with respect to <br /> glycerol was maintained.

Characterization and blending of polyhydroxyalkanoate (PHA) produced by Bacillus safensis FO-366(T) on cassava peels

Plastic industry has contributed significantly to the current state of environmental damage because the polymeric materials used so far in various applications are not biodegradable. Thus, the need for viable and sustainable solutions to reduce the environmental impact and have better performance than the options currently available. In this regard, biodegradable polymers emerged as one of the solutions to cushion impact of plastics waste disposal on the environment. Cassava peels were dried and made into powder, which was used for this study with Bacillus safensis FO-366(T). After 48 hrs of incubation the pellets were extracted and purified with chloroform. The pellets were dried and characterised. The FTIR and GCMS revealed the presence of 3HD methyl ester as the prominent monomers of PHA. The blends showed better mechanical properties than PLA and PE. This study revealed the potential of cassava peels as a carbon source for production of biodegradable polymer.