A Study Of Polyhydroxyalkanoate Production Of A Marine Roseobacter Strain And Polysaccharides Degradation Of A Bacteroidetes

Polyhydroxyalkanoate(PHA),a family of naturally-occurring biopolyesters synthesized by numerous microorganisms,has been recognized as a suitable alternative owing to its similar physico-chemical characteristics of the traditional plastics but prior to which for its biocompatibility and biodegradability.Among the nearly 150 different PHA monomers identified till date,poly(3-hydroxybutyrate)(PHB),a short chain length PHA discovered by Lemoigne in 1926.is the first and best-characterized form.PHB is a thermoplastic polyester with mechanical properties close to those of polypropylene,which can be extruded,moulded and spun proved by tests.Marine Roseobacter clade bacteria like Dinoroseobacter shibae DFL 12,Roseibacterium beibuensis JLT1202r,Roseobacter litoralis OCh 149 have been previously reported to be capable of PHA accumulation.Thiobacimonas profunda JLT2016,a Roseobacter clade bacteria isolated from deep sea which possesses Sox enzyme complex and ribulose bisphosphate carboxylase(RuBisCO),making it possible to accomplish the oxidation of reduced sulphur and CO2 fixing for PHA production.The present work involved investigation of a previously reported sulphur-oxidizing Roseobacter clade bacterial strain Thiobacimonas profunda JLT2016 for production of PHA under different metabolisms.Nile red fluorescence proved the presence of lipidic granules within the bacterial cells.Transmission electron microscopy was also done.PHA produced by JLT2016 was identified as PHB according to the characteristic peaks detected in FT-IR spectrum and further confirmed by 1H and 13C N-MR spectrums.T.profunda JLT2016 was incubated under heterotrophic culture,chemolithoheterotrophic culture and mixotrophic culture with glucose,sodium sulphide and sodium bicarbonate served as substrates of energy source.The highest PHA production was obtained under chemolithoheterotrophic culture,in which PHB yields reached 60%of cell dry weight(CDW)and CDW reached 2.872 g/L.The experiments showed feasibility in using waste as raw materials to cut down the production costs through the application of metabolically diverse marine bacteria.Complete genome sequencing information of Echinicola rosea JL3085 was analyzed.399 CAZymes were predicted in the genome according to hmmscan v3.1b2 responsible for the degradation of pectin,xylan and arabinogalactan which was further confirmed by growth experiments.Therefore,there is considerable interest in exploring the complete genome sequence information of this strain and its potential industrial applications.