IMPLEMENTATION OF STUBBLE WASTE FOR BIOTRANSFORMATION TO INDUSTRIALLY IMPORTANT CHEMICALS

Abstract

The lignocellulosic biomass - paddy straw, corn straw, wheat straw etc are known as stubble waste. Setting fire to stubble waste is the source of air pollution causing major risks to human health and the environment. The problem which occurs due to its burning has an impact on the local and regional level. It releases harmful gases in the atmosphere together with particulate matter and kills useful micro-organisms in the soil as well as causing soil erosion. The proper utilization of stubble waste is of utmost importance to reduce the strain on the environment. Thus, treating lignocellulosic waste as a valuable resource is an essential pillar in waste management. In the proposed project, compositional analysis will be done for homogenized corn stover. It was fermented using two methodologies – Solid state fermentation (SSF) and Submerged fermentation (SmF) to produce microbial enzymes and Polyhydroxyalkanoates (PHA). Corn stover is the residue that is left in the field after the grain is harvested and thus, can be used as feedstock for valuable product formation. Corn stover undergoes pretreatment to break the recalcitrant and complex structure of biomass and expose the carbohydrate fractions. Pretreatment methods include acid / alkali hydrolysis, steam explosion, enzymatic hydrolysis and others. After the pretreatment method, cellulosic and hemi cellulosic fraction is hydrolyzed to attain monomeric sugarslike glucose and ix xylose. The sugar hydrolysate gained from the corn stover is then fermented using microorganisms to convert to PHA. The process of fermentation includes cultivating microorganisms under controlled parameters such as temperature, Ph, time and nitrogen / carbon supply. The extraction of PHA from the biomass by using methods such as solvent extraction, precipitation and cell disruption techniques. Furthermore, purification of the extracted PHA to remove the impurities. Polyhydroxyalkonate are biodegradable polymers which can be produced by microorganisms from lignocellulosic biomass. Cheap and easily available raw material such as corn stover waste has potential to lessen the cost of PHA synthesis. In this research study, corn stover is utilized for sodium hydroxide alkali pre-treatment and optimization with central composite design (CCD) for high cellulose and low lignin followed by characterization using FT-IR, TGA and SEM. Design expert performed optimized condition of alkali pre-treated corn stover for high total reducing sugar (TRS) enhancement using CCD using Response surface methodology (RSM). The optimized condition by RSM produced total reducing sugar yield of 707.19 mg/g. Fermentation using corn stover hydrolysate by Pseudomonas putida MTCC 2475 gave mcl- PHA detected through GC-MS/MS and characterization of PHA film by DSC, FTIR and NMR. Thus, this research paper focus on use of agriculture (stubble) waste as alternative feedstock for PHA production. Phanerochaete chrysosporium is a white rot fungus is capable to produce comprehensive extracellular enzymes. These microbial enzymes have important applications in disrupting complex structure of plant cell wall, decolourization of synthetic dyes, de-pulping and many more. Solid state fermentation is an economical and sustainable process. Hence it is used for high enzyme production yield by using lignocellulosic biomass as substrate. Lignocellulytic enzymes like are produced from x an agriculture waste. In this research paper, untreated as well as alkali pre-treated corn stover were used as substrate for enzyme production. Fungal strain was used for enzymes including cellulases and Manganese peroxidase production. The maximum endoglucanase production was observed 121.21 ± 0.90 U/ml on 9 th day and 79.75 ± 0.57 U/ml on 6th day in untreated and treated biomass respectively. The maximum exoglucanase production was reached 2.46 ± 0.008 FPU/ml on 3rd and 0.92 ±0.002 FPU/ml on 6th day in untreated and treated biomass respectively. The maximum manganese peroxidase production was reached on 5076.81 U/L on 6 th and 1127.58 ±0.23 U/L on 3 rd day untreated and treated biomass respectively. Thus, corn stover is abundant renewable sustainable biomass for enzyme production. The economic viability of using corn biomass for PHA and microbial enzymes production depends on many factors like the availability of cost stover, pretreatment efficiency, PHA / enzymes yield and market demand of the bioproducts. The sustainable practices and conversion technologies is crucial to bio transform corn stover to PHA and microbial enzymes with the help of commercially viable and environment friendly methods.