Recombinant production of poly-(3-hydroxybutyrate) by Bacillus megaterium utilizing millet bran and rapeseed meal hydrolysates

Subbi Rami Reddy Tadi; Som Dutt Ravindran; Rengesh Balakrishnan; Senthilkumar Sivaprakasam

doi:10.1016/j.biortech.2021.124800

Recombinant production of poly-(3-hydroxybutyrate) by Bacillus megaterium utilizing millet bran and rapeseed meal hydrolysates

Bioresour Technol. 2021 Apr:326:124800. doi: 10.1016/j.biortech.2021.124800. Epub 2021 Feb 2.

Authors

Subbi Rami Reddy Tadi¹, Som Dutt Ravindran², Rengesh Balakrishnan³, Senthilkumar Sivaprakasam⁴

Affiliations

¹ BioPAT Laboratory, Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati 781039, Assam, India.
² Department of Biotechnology, Manipal Institute of Technology, Manipal 576104, Karnataka, India.
³ Department of Pharmaceutical Technology, Mahendra Engineering College, Namakkal District 637503, Tamil Nadu, India.
⁴ BioPAT Laboratory, Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati 781039, Assam, India. Electronic address: senthilkumar@iitg.ac.in.

PMID: 33556706
DOI: 10.1016/j.biortech.2021.124800

Abstract

Fermentative poly-3-hydroxybutyrate (PHB) production is mainly limited by the cost of raw material. In this present study, low-cost feedstock viz., millet bran residue (MBRH) and rapeseed meal hydrolysates were successfully utilized for PHB production. Metabolic engineering of Bacillus megaterium by co-expression of both precursor (phbRBC) and NADPH cofactor regeneration (zwf) genes resulted in 2.67-fold enhancement in PHB accumulation compared to wild strain. Modified logistic model characterized B.megaterium growth and PHB production effectively. The kinetic analysis proved that maximum cell concentration (15.01 g.L^-1) and growth-associated constant (0.22 g.g^-1) were found to be higher for initial MBRH concentration (S₀ = 20 g.L^-1). PHB production kinetics elucidated its expression in B.megaterium was growth-associated. PHB synthesized by B.megaterium was characterized using FTIR, NMR, XRD, DSC/TGA, FESEM and the physio-chemical properties enumerated its as a potential biodegradable plastic for industrial application.

Keywords: Bacillus megaterium; Kinetic modeling; Metabolic engineering; Millet bran hydrolysate; Poly-3-hydroxybutyrate.

MeSH terms

3-Hydroxybutyric Acid
Bacillus megaterium*
Brassica napus*
Hydroxybutyrates
Kinetics
Millets
Polyesters

Substances

Hydroxybutyrates
Polyesters
3-Hydroxybutyric Acid