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Background: Polyhydroxybutyrate (PHB) and polyhydroxybutyrate-co-hydroxyvalerate (PHBV) are the most common polyhydroxyalkanoates (PHAs). They are important candidates for biodegradable plastics that accumulate in the cytoplasm in the form of intracellular granules under unbalanced growth conditions. The present study focused on the production and optimization of PHAs from Paraburkholderia sp. PFN29 for the first time under submerged fermentation. Results: Two hundred bacterial isolates were collected from soil samples in Thailand, six of which were found to accumulate PHB using the Nile red staining method. Six isolates were identified by 16S rDNA gene sequencing and were shown to be closely related to the genera Azotobacter, Sphingobium and Paraburkholderia. The best strain, Paraburkholderia sp. PFN29, showed the highest PHB concentration (5 ± 0.17 g/L). Optimization of PHB accumulation was achieved in modified medium containing 3% (w/v) glucose, and 0.1% (w/v) (NH4)2Fe(SO4) with incubation at pH 7.0 and 35°C for 96 h with shaking at 200 rpm. In preliminary PHBV synthesis, PFN29 was utilized to synthesize PHBV from glucose and organic acids (levulinic acid and propionic acid). ¹H nuclear magnetic resonance (¹H NMR) spectroscopy and gas chromatography-mass spectrometry (GC/MS) analyses confirmed the extracted PHAs compared to standard PHB and PHBV. Conclusions: PFN29 can be used for feasible PHB production with a PHB content of up to 97.3% of 5.14 ± 0. 17 g/L CDW. The PHBV concentration can be further improved by optimizing the production parameters as cosubstrates. The present study provides useful data on PHA production by Paraburkholderia, which may be used as a candidate species for commercial PHA production. [ABSTRACT FROM AUTHOR]

PVA is biodegradable plastic and a water-soluble synthetic polymer that plays a significant role in industry. A large amount of PVA in wastewater causes heavy environmental pollution in terms of accumulation, disposal, and long-term degradation; therefore it must be removed from wastewater before the water is discharged. In this study, NS3 mixed microbial culture, capable of completely degrading 5 g.L-1 polyvinyl alcohol (PVA), was isolated from landfill soil using the enrichment culture method. It completely degraded PVA at an initial concentration in the range 1 - 5 g.L-1 over 5 - 20 days of incubation with continuous shaking at 30 °C. Moreover, mixed microbial cultures were found to remove PVA at a high range concentration of 10 - 25 g.L-1. Urea and glucose added to the medium inhibited PVA degradation by increasing the pH to a strongly alkaline level, which would cause cell viability and enzyme stability. The FT-IR spectra and SEM imaging revealed the mechanisms and the physical degradation of PVA films, respectively. PVA uptake in bacterial cells produced a dent in the cell surface, which represented the consumption of PVA by bacterial cell. The PVA-degrading mixed microbial culture is the first reported in Thailand and can be beneficial in PVA wastewater treatment. [ABSTRACT FROM AUTHOR]

Four potential polyester-degrading bacterial strains were isolated from compost soils in Thailand. These bacteria exhibited strong degradation activity for polyester biodegradable plastics, such as polylactic acid (PLA), polycaprolactone (PCL), poly-(butylene succinate) (PBS) and polybutylene succinate-co-adipate (PBSA) as substrates. The strains, classified according to phenotypic characteristics and 16S rDNA sequence, belonging to the genera Actinomadura, Streptomyces and Laceyella, demonstrated the best polyester- degrading activities. All strains utilized polyesters as a carbon source, and yeast extract with ammonium sulphate was utilized as a nitrogen source for enzyme production. Optimization for polyester-degrading enzyme production by Actinomadura sp. S14, Actinomadura sp. TF1, Streptomyces sp. APL3 and Laceyella sp. TP4 revealed the highest polyester-degrading activity in culture broth when 1% (w/v) PCL (18 U/mL), 0.5% (w/v) PLA (22.3 U/mL), 1% (w/v) PBS (19.4 U/mL) and 0.5% (w/v) PBSA (6.3 U/mL) were used as carbon sources, respectively. All strains exhibited the highest depolymerase activities between pH 6.0-8.0 and temperature 40-60°C. Partial nucleotides of the polyester depolymerase gene from strain S14, TF1 and APL3 were studied. We determined the amino acids making up the depolymerase enzymes had a highly conserved pentapeptide catalytic triad (Gly-His-Ser-Met-Gly), which has been shown to be part of the esterase-lipase superfamily (serine hydrolase). [ABSTRACT FROM AUTHOR]

Currently, bio-based plastics are considered the most promising and environmentally friendly alternative to replace petroleum-based plastics to reduce their environmental impacts. The aim of this research work is to assess and compare the life cycle impact of three types of bio-based boxes (namely, polylactic acid from sugarcane, polylactic acid from sugarcane-starch blends and polybutylene succinate from sugarcane and corn) and petroleum-based boxes of polystyrene. The locations of the plantation stage are focused in 4 provinces, namely, Kanchanaburi, Sakaeo, Prachinburi, and Chonburi provinces, in Thailand. The total impact using the external environmental cost (unit: THB equivalent) is performed at two impact categories: carbon footprint and fresh water consumption. The results from this study indicate that polybutylene succinate reveals the lowest water footprint at 0.38 m 3 H 2 O of all the bio-based boxes and presents the second lowest water deprivation at 0.008 m 3 H 2 O equivalent and the lowest carbon footprint at −0.06 kg CO 2 equivalent. The lowest water footprints for all bio-based boxes production chains are found in Kanchanaburi and Chonburi provinces because the highest sugarcane and corn yield were observed, respectively, whereas, the minimum of water deprivation for all bio-based boxes production chains are clearly observed in Sakaeo province because of the lowest amount of chemicals used during plantation stage. The total impact on carbon footprint decreased by 26–69% for the production of bio-based boxes because CO 2 absorption from the photosynthetic reactions during the plantation stages were included. In conclusion, for bio-based boxes, the polybutylene succinate box showed the lowest total externality cost of 0.046 THB equivalent on production chain in Sakaeo province. This externality accounts for 64–74% of total cost for freshwater consumption but only accounts for 26–36% of total cost for carbon footprint. These results are beneficial to supporting the development for establishing bio-plastics industry in aspects of water used and carbon footprint. Therefore, the effective strategies for preparing a sufficient supply of irrigation system or efficient water management and appropriate performance from agrochemicals used for supporting the feedstocks production to bio-plastics industry production chains should be proposed. [ABSTRACT FROM AUTHOR]

Forty agricultural soils were collected from Chiang Mai and Lampang provinces in northern Thailand. Bacteria, actinomycetes and fungi were isolated and screened for their ability to degrade polylactic acid (PLA), polycaprolactone (PCL) and poly(butylene succinate) (PBS) by the agar diffusion method. Sixty-seven actinomycetes, seven bacteria and five fungal isolates were obtained. The majority of actinomycetes were Streptomyces based on morphological characteristic, chemotaxonomy and 16S rRNA gene data. Seventy-nine microorganisms were isolated from 40 soil samples. Twenty-six isolates showed PLA-degradation (32.9 %), 44 isolates showed PBS-degradation (55.7 %) and 58 isolates showed PCL-degradation (73.4 %). Interestingly, 16 isolates (20.2 %) could degrade all three types of bioplastics used in this study. The Amycolatopsis sp. strain SCM_MK2-4 showed the highest enzyme activity for both PLA and PCL, 0.046 and 0.023 U/mL, respectively. Moreover, this strain produced protease, esterase and lipase on agar plates. Approximately, 36.7 % of the PLA film was degraded by Amycolatopsis sp. SCM_MK2-4 after 7 days of cultivation at 30 °C in culture broth. [ABSTRACT FROM AUTHOR]

Every year, thousands of tons of non-biodegradable plastic products are dumped into marine environments in Thailand's territorial seawater, impacting various marine animals. Recently, there has been a surge in interest in biodegradable plastics as a solution for aquatic environments. However, in Thailand's coastal waters, no suitable biodegradable plastic has been used as ocean-biodegradable packaging. Among them, polyhydroxyalkanoates (PHAs) have excellent biodegradability even in seawater, which is the desired property for packaging applications in tourist places such as plastic bags and bottles. In this report, we assess the environment's safety and study the biodegradation in Thailand seawater of polyhydroxybutyrate (PHB) and PHA copolymer (PHBVV) that were successfully synthesized by bacteria with similar molecular weight. The two types of extracted PHA samples were preliminary biodegradability tested in the marine environment compared with cellulose and polyethylene. Within 28 days, PHB and PHBVV could be biodegraded in both natural and synthetic seawater with 61.2 and 96.5%, respectively. Furthermore, we assessed residual toxicity after biodegradation for environmental safety using seawater samples containing residual digested compounds and the standard guide for acute toxicity tests. It was discovered that marine water mites (Artemia franciscana) have 100 percent viability, indicating that they are non-toxic to the marine environment. [ABSTRACT FROM AUTHOR]