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Microbial synthesis of polyhydroxyalkanoate using seaweed-derived crude levulinic acid as co-nutrient.

Bera A1, Dubey S2, Bhayani K2, Mondal D1, Mishra S3, Ghosh PK4.

Int J Biol Macromol. 2015 ;72:487-94.

1Academy of Scientific and Innovative Research, Gijubhai Badheka Marg, Bhavnagar 364002, India.

2CSIR-Central Salt & Marine Chemicals Research Institute, G. B. Marg, Bhavnagar 364002, India.

3Academy of Scientific and Innovative Research, Gijubhai Badheka Marg, Bhavnagar 364002, India; CSIR-Central Salt & Marine Chemicals Research Institute, G. B. Marg, Bhavnagar 364002, India. Electronic address: [email protected]

4Academy of Scientific and Innovative Research, Gijubhai Badheka Marg, Bhavnagar 364002, India; CSIR-Central Salt & Marine Chemicals Research Institute, G. B. Marg, Bhavnagar 364002, India. Electronic address: [email protected]

 

Abstract

Production of polyhydroxyalkanoates (PHAs) from Jatropha biodiesel residues, namely crude glycerol and oil cake hydrolysate, has been reported previously. Halomonas hydrothermalis (MTCC accession no. 5445; NCBI Genbank accession no. GU938192), a wild marine strain, was used in the bio-synthesis. The present study was initiated to vary the properties of the polymer. Seaweed-derived crude levulinic acid (SDCLA), containing formic acid, residual sugars and dissolved minerals additionally, was proposed as co-feed along with the biodiesel residues. Experiments were conducted at 100mL scale in batch process. Whereas the PHA yield was only 0.40 ± 0.01 g when only biodiesel residues were employed, it rose to 1.07 ± 0.02 g in presence of 0.35% (w/v) of SDCLA. The corresponding carbon utilisation efficiencies were 29.3% and 57.5%, respectively. 3-Hydroxy valerate incorporation in the PHA was pronounced in presence of SDCLA, with associated changes in polymer properties. The microbialsynthesis fared poorly when SDCLA was substituted with pure levulinic acid. Thus, Halomonas hydrothermalis had a poor response to levulinic acid, as such, and other constituents present in SDCLA appear to have played a vital role in bacterial cell division and accumulation of PHA. Biodegradability tests in moist soil were also conducted as part of the study. Marine microalgal cultivation for biodiesel and seaweed cultivation for fuels may help generate biodiesel residues and crude levulinic acid in proximity, which would open up the possibility of large scale PHA manufacture in efficient and practical manner in the future through the methodology of the present study.

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