Developing Microbial Co-Culture System for Enhanced Polyhydroxyalkanoates (PHA) Production Using Acid Pretreated Lignocellulosic Biomass.

Rijuta Ganesh Saratale,Han-Seung Shin,Gajanan Sampatrao Ghodake,Ganesh Dattatraya Saratale,Ram Naresh Bharagava,Manu Kumar,Dong-Su Kim,Sunita Varjani,Supriya Nair,Avinash Ashok Kadam,Si-Kyung Cho

doi:10.3390/polym14040726

Abstract

In the growing polymer industry, the interest of researchers is captivated by bioplastics production with biodegradable and biocompatible properties. This study examines the polyhydroxyalkanoates (PHA) production performance of individual Lysinibacillus sp. RGS and Ralstonia eutropha ATCC 17699 and their co-culture by utilizing sugarcane bagasse (SCB) hydrolysates. Initially, acidic (H2SO4) and acidified sodium chlorite pretreatment was employed for the hydrolysis of SCB. The effects of chemical pretreatment on the SCB biomass assembly and its chemical constituents were studied by employing numerous analytical methods. Acidic pretreatment under optimal conditions showed effective delignification (60%) of the SCB biomass, leading to a maximum hydrolysis yield of 74.9 ± 1.65% and a saccharification yield of 569.0 ± 5.65 mg/g of SCB after enzymatic hydrolysis. The resulting SCB enzymatic hydrolysates were harnessed for PHA synthesis using individual microbial culture and their defined co-culture. Co-culture strategy was found to be effective in sugar assimilation, bacterial growth, and PHA production kinetic parameters relative to the individual strains. Furthermore, the effects of increasing acid pretreated SCB hydrolysates (20, 30, and 40 g/L) on cell density and PHA synthesis were studied. The effects of different cost-effective nutrient supplements and volatile fatty acids (VFAs) with acid pretreated SCB hydrolysates on cell growth and PHA production were studied. By employing optimal conditions and supplementation of corn steep liquor (CSL) and spent coffee waste extracted oil (SCGO), the co-culture produced maximum cell growth (DCW: 11.68 and 11.0 g/L), PHA accumulation (76% and 76%), and PHA titer (8.87 and 8.36 g/L), respectively. The findings collectively suggest that the development of a microbial co-culture strategy is a promising route for the efficient production of high-value bioplastics using different agricultural waste biomass.

Highlights

1.1.IntroductionSynthetic plastics plastics have have multiple multiple applications applications in in the the modern modern world world such such as as in infood foodSynthetic packaging, automotive industry, sports materials, agricultural, biomedical apparatus, and packaging, automotive industry, sports materials, agricultural, biomedical apparatus, and electronicmaterials. materials.GlobalGlobalplastic plasticproduction productionextended extendedto to359359million millionmetric metrictons tonsin in 2018, 2018, electronic equatedto to200 in2002 and50 50in in1976 1976[1].[1].,being beingresistant resistantto todegradation, degradation,large large equated amountsofofplastic plasticwaste wastediscarded discarded primarily open landfills dumpsites inflict seamounts primarily in in open landfills andand dumpsites inflict severe impacts on theon natural ecosystem, human health, and the environment [2,3]. [2,3]
It was estimated that accessible Lignocellulosic biomass (LC) biomass is approximately 150 billion tons per year globally [24]
PHA production economies using LC biomass relies on a substrate, choice of pretreatment, hydrolysis method, and fermentation conditions

Summary

Introduction

1.1.IntroductionSynthetic plastics plastics have have multiple multiple applications applications in in the the modern modern world world such such as as in infood foodSynthetic packaging, automotive industry, sports materials, agricultural, biomedical apparatus, and packaging, automotive industry, sports materials, agricultural, biomedical apparatus, and electronicmaterials. materials.GlobalGlobalplastic plasticproduction productionextended extendedto to359359million millionmetric metrictons tonsin in 2018, 2018, electronic equatedto to200 in2002 and50 50in in1976 1976[1].[1].,being beingresistant resistantto todegradation, degradation,large large equated amountsofofplastic plasticwaste wastediscarded discarded primarily open landfills dumpsites inflict seamounts primarily in in open landfills andand dumpsites inflict severe impacts on theon natural ecosystem, human health, and the environment [2,3]. [2,3].

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Results

Conclusion