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Characterization of Halophilic Bacteria Halomonas sp. to Produce Polyhydroxyalkanoates (PHAs)
Youjung KONG,Haeng-Geun CHA,Hye-ji JIN,Yu-Bin JEON,Jeong Chan JOO,Yung-Hun YANG,See-Hyoung PARK,Kyungmoon PARK 한국생물공학회 2021 한국생물공학회 학술대회 Vol.2021 No.10
Polyhydroxyalkanoates (PHAs) are polyesters of hydroxyalkanoic acid accumulated by numerous prokaryotes in the form of intracellular granules as storage of carbon and energy. In the previous study, we have obtained 5 kinds of halophilic bacteria with the potential for PHA-producing by using the PCR screening method. As the halophilic bacteria can grow in high salinity, the PHA production cost can be lowered due to low risk of contamination and simple extraction method using water. In this study, biological characterization and PHA productivity of Halomonas sp., showing the best productivity among them, were studied under the different conditions of medium, temperature, NaCl concentration, carbon source. In addition, PHA composition from Halomonas sp. was characterized as poly(3-hydroxybutyrate) (PHB) by gas chromatography (GC) and nuclear magnetic resonance (NMR).
Jeon Yubin,Jin HyeJi,Kong Youjung,Cha Haeng-Geun,Lee Byung Wook,Yu Kyungjae,Yi Byongson,Kim Hee-Taek,Joo Jeong Chan,Yang Yung-Hun,Lee Jongbok,Jung Sang-Kyu,Park See-Hyoung,Park Kyungmoon 한국미생물·생명공학회 2023 Journal of microbiology and biotechnology Vol.33 No.8
Poly(3-hydroxybutyrate) (PHB) is a biodegradable and biocompatible bioplastic. Effective PHB degradation in nutrient-poor environments is required for industrial and practical applications of PHB. To screen for PHB-degrading strains, PHB double-layer plates were prepared and three new Bacillus infantis species with PHB-degrading ability were isolated from the soil. In addition, phaZ and bdhA of all isolated B. infantis were confirmed using a Bacillus sp. universal primer set and established polymerase chain reaction conditions. To evaluate the effective PHB degradation ability under nutrient-deficient conditions, PHB film degradation was performed in mineral medium, resulting in a PHB degradation rate of 98.71% for B. infantis PD3, which was confirmed in 5 d. Physical changes in the degraded PHB films were analyzed. The decrease in molecular weight due to biodegradation was confirmed using gel permeation chromatography and surface erosion of the PHB film was observed using scanning electron microscopy. To the best of our knowledge, this is the first study on B. infantis showing its excellent PHB degradation ability and is expected to contribute to PHB commercialization and industrial composting.
Haeng-Geun CHA,Youjung KONG,Hee Taek KIM,Jeong Chan JOO,Jung-Oh AHN,Yung-Hun YANG,See-Hyoung PARK,Kyungmoon PARK 한국생물공학회 2021 한국생물공학회 학술대회 Vol.2021 No.10
Recently, as the concerns over environmental issues have increased, the market demand for the environmental friendly bio-based chemicals isincreasing rapidly. Glutaric acid, a metabolic intermediate in amino acid pathways, is becoming a potential C5 diacid chemical as a monomer for bio-polyamide and a plasticizer to substitute petroleum based phthalate plasticizers. Since it is too toxic to produce glutaric acid by chemical process, the whole cell bioconversion process was applied in this study. In order to convert 5-aminovaleric acid (5-AVA) to glutaric acid, the enzymes, 4-aminobutyrate aminotransferase (gabT from E. coli) and succinate semialdehyde dehydrogenase (gabD from E. coli), were used. In addition, glutamate oxidase (gox from S. mobaraensis) and NAD(P)H oxidase (nox from B. subtilis) were used to regenerate cofactors, α-KG and NAD⁺, respectively. The bioconversion rate from high concentration of 5-AVA to glutaric acid was decreased after 48 hours. In order to investigate the reasons of decrease in conversion rate, the cell viability and the residual enzyme activity were analyzed. To maintain the high conversion rate, the cell exchange method was adapted in high concentration 5-AVA.