Dataset Information

Microbial production and characterization of poly-3-hydroxybutyrate by Neptunomonas antarctica.

ABSTRACT: Considering the industrial interest of biodegradable polymer poly-3-hydroxybutyrate (PHB), the marine bacteria Neptunomonas antarctica was studied for its ability to accumulate PHB. The extracted polymer was confirmed to be PHB by nuclear magnetic resonance analysis. In shake flask cultures using natural seawater as medium components, PHB was produced up to 2.12 g/L with a yield of 0.18 g PHB/g fructose. In the presence of artificial seawater, the PHB titer and yield reached 2.13 g/L and 0.13 g PHB/g fructose, respectively. The accumulated polymer gradually decreased when fructose was exhausted, indicating that intracellular PHB was degraded by N. antarctica. The weight-average and number-average molecular weights of PHB produced within natural seawater were 2.4 × 10(5) g/mol and 1.7 × 10(5) g/mol, respectively. Our results highlight the potential of N. antarctica for PHB production with seawater as a nutrient source.

SUBMITTER: Liu XJ

PROVIDER: S-EPMC4975036 | biostudies-literature | 2016

REPOSITORIES: biostudies-literature

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Microbial production and characterization of poly-3-hydroxybutyrate by Neptunomonas antarctica.

Liu Xiao-Jie XJ Zhang Jie J Hong Peng-Hui PH Li Zheng-Jun ZJ

PeerJ 20160802

Considering the industrial interest of biodegradable polymer poly-3-hydroxybutyrate (PHB), the marine bacteria Neptunomonas antarctica was studied for its ability to accumulate PHB. The extracted polymer was confirmed to be PHB by nuclear magnetic resonance analysis. In shake flask cultures using natural seawater as medium components, PHB was produced up to 2.12 g/L with a yield of 0.18 g PHB/g fructose. In the presence of artificial seawater, the PHB titer and yield reached 2.13 g/L and 0.13 g ...[more]

PMID: 27547584

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Project description:BackgroundDue to various environmental problems, biodegradable polymers such as poly (3-hydroxybutyrate) (PHB) have gained much attention in recent years. Purple non-sulfur (PNS) bacteria have various attractive characteristics useful for environmentally harmless PHB production. However, production of PHB by PNS bacteria using genetic engineering has never been reported. This study is the first report of a genetically engineered PNS bacterial strain with a high PHB production.ResultsWe constructed a poly (3-hydroxyalkanoate) depolymerase (phaZ) gene-disrupted Rhodobacter sphaeroides HJ strain. This R. sphaeroides HJ?phaZ (pLP-1.2) strain showed about 2.9-fold higher volumetric PHB production than that of the parent HJ (pLP-1.2) strain after 5 days of culture. The HJ?phaZ strain was further improved for PHB production by constructing strains overexpressing each of the eight genes including those newly found and annotated as PHB biosynthesis genes in the KEGG GENES Database. Among these constructed strains, all of gene products exhibited annotated enzyme activities in the recombinant strain cells, and HJ?phaZ (phaA3), HJ?phaZ (phaB2), and HJ?phaZ (phaC1) showed about 1.1-, 1.1-, and 1.2-fold higher volumetric PHB production than that of the parent HJ?phaZ (pLP-1.2) strain. Furthermore, we constructed a strain that simultaneously overexpresses all three phaA3, phaB2, and phaC1 genes; this HJ?phaZ (phaA3/phaB2/phaC1) strain showed about 1.7- to 3.9-fold higher volumetric PHB production (without ammonium sulfate; 1.88?±?0.08 g l-1 and with 100 mM ammonium sulfate; 0.99?±?0.05 g l-1) than those of the parent HJ (pLP-1.2) strain grown under nitrogen limited and rich conditions, respectively.ConclusionIn this study, we identified eight different genes involved in PHB biosynthesis in the genome of R. sphaeroides 2.4.1, and revealed that their overexpression increased PHB accumulation in an R. sphaeroides HJ strain. In addition, we demonstrated the effectiveness of a phaZ disruption for high PHB accumulation, especially under nitrogen rich conditions. Furthermore, we showed that PNS bacteria may have some unidentified genes involved in poly (3-hydroxyalkanoates) (PHA) biosynthesis. Our findings could lead to further improvement of environmentally harmless PHA production techniques using PNS bacteria.

Dataset Information

Microbial production and characterization of poly-3-hydroxybutyrate by Neptunomonas antarctica.

Publications

Microbial production and characterization of poly-3-hydroxybutyrate by Neptunomonas antarctica.

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