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Polyhydroxyalkanoate biosynthesis and simplified polymer recovery by a novel moderately halophilic bacterium isolated from hypersaline microbial mats
Author(s) -
Rathi D.N.,
Amir H.G.,
Abed R.M.M.,
Kosugi A.,
Arai T.,
Sulaiman O.,
Hashim R.,
Sudesh K.
Publication year - 2013
Publication title -
journal of applied microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.889
H-Index - 156
eISSN - 1365-2672
pISSN - 1364-5072
DOI - 10.1111/jam.12083
Subject(s) - polyhydroxyalkanoates , halophile , halomonas , polyhydroxybutyrate , valerate , food science , chemistry , halotolerance , bacteria , lysis , nuclear chemistry , extremophile , biomass (ecology) , fermentation , biochemistry , biology , microorganism , butyrate , genetics , agronomy
Aims Halophilic micro‐organisms have received much interest because of their potential biotechnological applications, among which is the capability of some strains to synthesize polyhydroxyalkanoates ( PHA ). H alomonas sp. SK 5, which was isolated from hypersaline microbial mats, accumulated intracellular granules of poly(3‐hydroxybutyrate) [P(3 HB )] in modified accumulation medium supplemented with 10% (w/v) salinity and 3% (w/v) glucose. Methods and Results A cell density of approximately 3·0 g l −1 was attained in this culture which yielded 48 wt% P(3 HB ). The bacterial strain was also capable of synthesizing poly(3‐hydroxybutyrate‐ co ‐3‐hydroxyvalerate) [P(3 HB ‐ co ‐3 HV )] when cofed with relevant precursors. Feeding with sodium valerate (0·7 mol l −1 carbon) at various time intervals within 36 h resulted in 3 HV molar fractions ranging from 6 up to 54 mol%. Oil palm trunk sap ( OPTS ) and seawater as the carbon source and culture medium respectively facilitated a significant accumulation of P (3 HB ). Simplified downstream processing based on osmotic lysis in the presence of alkali/detergent for both dry and wet biomass resulted in approximately 90–100% recovery of polymers with purity as high as 90%. Weight‐average molecular weight ( M w ) of the polymers recovered was in the range of 1–2 × 10 6 . Conclusions H alomonas sp. SK 5 was able to synthesize P(3 HB ) homopolymer as well as P (3 HB ‐ co ‐3 HV ) copolymer from various carbon sources. Significance and Impact of the Study This is the first time a comprehensive study of both production and downstream processing is reported for H alomonas spp.