Sustainable Bioconversion of Cassava Waste to Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) by Halogeometricum borinquense Strain E3
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The production of sago starch from cassava at an industrial scale in Salem, Tamil Nadu, India results in discharge of starch/carbon-rich fibrous waste and effluents, contributing to a major environmental problem. The present study aimed at exploring the potential of an extremely halophilic archaeon, Halogeometricum borinquense strain E3 to utilize starch and cassava waste (CW) as carbon substrate and synthesis of polyhydroxyalkanoates (PHAs). The culture E3 was able to grow and utilize both starch and CW with maximum PHA concentration of 4.6 g L−1 and 1.52 g L−1, respectively. When grown in starch, the cells of the strain E3 appeared bright orange due to produced carotenoids, whereas, when grown in CW the culture cells appeared light brown due to masking of the pigment by the impurities from CW hydrolysate. The polymer obtained from starch and CW hydrolysate was characterized using UV–Visible spectrophotometry, differential scanning calorimetry, fourier transform infrared spectroscopy, nuclear magnetic resonance spectroscopy, and was reported to be a co-polymer of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) [P(3HB-co-3HV)] comprising of 13.11% and 19.65% 3HV units, respectively. The present investigation is supportive of our previous studies which indicated Hgm. borinquense strain E3 as an attractive candidate for production of co-polymer of P(3HB-co-3HV) when fed with commercial substrate such as glucose and agro-industrial waste such as sugarcane bagasse.
KeywordsArchaea Cassava waste Polyhydroxyalkanoates Copolymer Halophiles
Chemical oxygen demand
Cell dry mass
Revolutions per minute
B. B. Salgaonkar thank Council of Scientific and Industrial Research (CSIR), India for Research Associateship (RA) (09/919(0030)/2016-EMR-I). Authors acknowledge the Sophisticated Instrumentation Facility (SIF), Chemistry Division, VIT University, Vellore for FT-IR and 1H NMR analysis. Authors are grateful to Prof. Narendra Nath Ghosh, Dept. of Chemistry, BITS Pilani Goa Campus, for DSC analysis.
BBS, KM and JMB conceived the idea, designed the experiments and analyzed the data. BBS performed the experiments and drafted the manuscript, which was reviewed and edited by KM and JMB.
Compliance with Ethical Standards
Conflict of interest
The authors declare that they have no competing interests.
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