Journal of Environmental Biology

Cost-effective substrates for production of poly-β-hydroxybutyrate by a newly isolated Bacillus cereus PS-10

Priyanka Sharma and Bijender Kumar Bajaj*

School of Biotechnology, University of Jammu, Jammu-180 006, India

*Corresponding Author E-mail: bajajbijenderk@gmail.com

Publication Data

Paper received:

26 April 2014

Revised received:

20 September 2014

Re-revised received:

14 November 2014

Accepted:

25 November 2014

Abstract

Poly-b-hydroxybutyrate (PHB) may serve as one of the imperative substitutes for petroleum derived plastics because of their close functional analogy and biodegradation quality. In the present study, PHB producing ability of bacterial isolates was examined on low-cost agro industrial residues. Isolate PS-10 from domestic waste landfills, identified as Bacillus cereus PS-10 produced and accumulated appreciable amount of PHB. Bacillus cereus PS-10 was capable of using a wide variety of agro-based residues viz. maize bran, rice husk, wood waste, molasses, whey etc. as cost-effective carbon sources for PHB production. Molasses at 3% (w/v) supported maximum PHB production (9.5 gl^-1) and was followed by glycerol (8.9 gl^-1) at 2% (w/v). Certain carbon sources like almond shell powder and walnut shell powder are being reported for the first time for PHB production and supported reasonable PHB yield i.e. 6.6 and 4.6 gl^-1, respectively. Different cost-effective nitrogen sources like corn steep liquor, chick pea bran, soy bean meal, mustard cake etc. were used for PHB production. Highest PHB production was observed at pH 7 (9.6 gl^-1) after 48 hrs of fermentation, although B. cereus PS-10 grew and produced PHB over pH range of 5-9. Optimum inoculum level for maximum PHB production was found to be 5% v/v (A₆₀₀ 0.9; approximately 10⁸ cfu ml^-1). Fourier transform infrared spectroscopy (FT-IR) analysis of the extracted PHB showed characteristic peaks (1721.95, 1632.19 and 2926.43 cm^-1) similar to standard PHB. Melting point of PHB was found to be 185oC. Bacillus cereus PS-10 may be a sound PHB producer, especially by exploiting low cost substrates. ???  

 Key words

Agroindustrial residues, Bacillus cereus, Cost-effective carbon sources, PHB production 

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