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

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

doi:10.3390/polym14040726

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

Polymers (Basel). 2022 Feb 14;14(4):726. doi: 10.3390/polym14040726.

Affiliations

¹ Research Institute of Biotechnology and Medical Converged Science, Dongguk University-Seoul, Ilsandong-gu, Goyang-si 10326, Gyeonggi-do, Korea.
² Department of Biological and Environmental Science, Dongguk University, Ilsandong-gu, Goyang-si 10326, Gyonggi-do, Korea.
³ Department of Life Science, Dongguk University-Seoul, 32 Dongguk-ro, Ilsandong-gu, Goyang-si 10326, Gyeonggi-do, Korea.
⁴ Department of Environmental Microbiology, School for Environmental Sciences Babasaheb Bhimrao Ambedkar University (A Central University), Lucknow 226 025, Uttar Pradesh, India.
⁵ Gujarat Pollution Control Board, Gandhinagar 382 010, Gujarat, India.
⁶ Department of Research and Development, SRL Limited, Prime Square, S. V. Road, Goregaon (W), Mumbai 400 062, Maharashtra State, India.
⁷ Department of Environmental Science and Engineering, Ewha Womans University, Seoul 120-750, Korea.
⁸ Department of Food Science and Biotechnology, Dongguk University-Seoul, Ilsandong-gu, Goyang-si 10326, Gyeonggi-do, Korea.

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.

Keywords: Lysinibacillus sp. RGS; Ralstonia eutropha ATCC 17699; acid pretreatment; co-culture strategy; polyhydroxyalkanoates production; sugarcane bagasse.