Production of polyhydroxyalkanoates from methanol by a new methylotrophic bacterium Methylobacterium sp. GW2

• Published in: Applied microbiology and biotechnology 2006-11, Vol.73 (1), p.211-218
• Main Authors: Yezza, A, Fournier, D, Halasz, A, Hawari, J
• Format: Article
• Language: English
• Subjects: Bacteria; Biological and medical sciences; Biopolymers - chemistry; Biotechnology; DNA, Bacterial - chemistry; DNA, Bacterial - genetics; DNA, Ribosomal - chemistry; DNA, Ribosomal - genetics; Ethanol - metabolism; Fermentation; Fundamental and applied biological sciences. Psychology; Genes, rRNA; Hydroxybutyrates - metabolism; Industrial Waste; Methanol; Methanol - metabolism; Methylobacterium; Methylobacterium - classification; Methylobacterium - isolation & purification; Methylobacterium - metabolism; Methylobacterium - ultrastructure; Microscopy, Electron, Transmission; Molecular Sequence Data; Molecular Weight; Pentanoic Acids - metabolism; Phylogeny; Polyesters - metabolism; Polyhydroxyalkanoates; RNA, Bacterial - genetics; RNA, Ribosomal, 16S - genetics; Sequence Analysis, DNA; Sequence Homology, Nucleic Acid; Studies; Succinic Acid - metabolism; Water Microbiology
• ISSN: 0175-7598; 1432-0614
• DOI: 10.1007/s00253-006-0458-7

A new bacterial strain, isolated from groundwater contaminated with explosives, was characterized as a pink-pigmented facultative methylotroph, affiliated to the genus Methylobacterium. The bacterial isolate designated as strain GW2 was found capable of producing the homopolymer poly-3-hydroxybutyrate (PHB) from various carbon sources such as methanol, ethanol, and succinate. Methanol acted as the best substrate for the production of PHB reaching 40 % w/w dry biomass. PHB accumulation was observed to be a growth-associated process, so that there was no need for two-step fermentation. Optimal growth occurred at 0.5 % (v/v) methanol concentration, and growth was strongly inhibited at [graphic removed] concentration above 2 % (v/v). Methylobacterium sp. strain GW2 was also able to accumulate the copolyester poly-3-hydroxybutyrate-poly-3-hydroxyvalerate (PHB/HV) when valeric acid was supplied as an auxiliary carbon source to methanol. After 66 h, a copolymer content of 30 % (w/w) was achieved with a PHB to PHV ratio of 1:2. Biopolymers produced by strain GW2 had an average molecular weight ranging from 229,350 to 233,050 Da for homopolymer PHB and from 362,430 to 411,300 Da for the copolymer PHB/HV.