Utilization of Sugarcane Bagasse by Halogeometricum borinquense Strain E3 for Biosynthesis of Poly(3-hydroxybutyrate-co-3-hydroxyvalerate).

Bhakti Salgaonkar,Judith Bragança

doi:10.3390/bioengineering4020050

Abstract

Sugarcane bagasse (SCB), one of the major lignocellulosic agro-industrial waste products, was used as a substrate for biosynthesis of polyhydroxyalkanoates (PHA) by halophilic archaea. Among the various wild-type halophilic archaeal strains screened, Halogeometricum borinquense strain E3 showed better growth and PHA accumulation as compared to Haloferaxvolcanii strain BBK2, Haloarcula japonica strain BS2, and Halococcus salifodinae strain BK6. Growth kinetics and bioprocess parameters revealed the maximum PHA accumulated by strain E3 to be 50.4 ± 0.1 and 45.7 ± 0.19 (%) with specific productivity (qp) of 3.0 and 2.7 (mg/g/h) using NaCl synthetic medium supplemented with 25% and 50% SCB hydrolysate, respectively. PHAs synthesized by strain E3 were recovered in chloroform using a Soxhlet apparatus. Characterization of the polymer using crotonic acid assay, X-ray diffraction (XRD), differential scanning calorimeter (DSC), Fourier transform infrared (FT-IR), and proton nuclear magnetic resonance (1H-NMR) spectroscopy analysis revealed the polymer obtained from SCB hydrolysate to be a co-polymer of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) [P(3HB-co-3HV)] comprising of 13.29 mol % 3HV units.

Highlights

Conventional plastics obtained from non-renewable petrochemical resources are creating environmental havoc due to their non-degradable nature
The Sugarcane bagasse (SCB) used in the present study appeared greenish-brown with a sweet odor and upon pulverization had total solids (TS) of 94.3 ± 0.14%, volatile solids (VS) of 92.7 ± 0.14%, and chemical oxygen demand (COD) of 1.18 ± 0.05 g/Kg
All four halophilic archaeal isolates were able to grow on NSM plates with Nile Red dye supplemented with SCB hydrolysate as substrate

Summary

Introduction

Conventional plastics obtained from non-renewable petrochemical resources are creating environmental havoc due to their non-degradable nature. To solve this problem, various bio-based materials derived from renewable resources have been explored as a replacement for conventional plastics. Carbon sources/substrates represent half of the PHA fermentation cost [5,6,7] Various strategies such as replacing commercial substrates with inexpensive renewable agro-industrial waste, finding novel high PHA-accumulating microorganisms or microbial strain improvements, and reducing the cost of PHA recovery/downstream process can make the overall fermentation process more cost-effective [4]

Methods

Results

Conclusion