Pretreatment optimization of Sorghum pioneer biomass for bioethanol production and its scale-up

Genomic driven factors enhance biocatalyst-related cellulolysis potential in anaerobic digestion

Anaerobic digestion (AD) is a promising technology to recover bioenergy from biodegradable biomass, including cellulosic wastes. Through a few fractionation/separation techniques, cellulose has demonstrated its potential in AD, but the performance of the process is rather substrate-specific, as cellulolysis bacteria are sensitive to the enzyme-substrate interactions. Cellulosome is a self-assembled enzyme complex with many functionalized modules in the bacteria which has been gradually studied, however the genomic fingerprints of the culture-specific cellulosome in AD are relatively unclear especially under processing conditions. To clarify the key factors affecting the cellulosome induced cellulolysis, this review summarized the most recent publications of AD regarding the fates of cellulose, sources and functional genes of cellulosome, and omics methods for functional analyses. Different processes for organic treatment including applying food grinds in sewer, biomass valorization, cellulose fractionation, microaeration, and enzymatic hydrolysis enhanced fermentation, were highlighted to support the sustainable development of AD technology.

Enhancement of Laccase Production by Optimizing the Cultural Conditions for Pleurotus sajor-caju in Solid-State Fermentation

Nowadays, a lot of interest has been given to the development of cost-effective and efficient enzyme production technologies. Laccase enzymes are widely used in biotechnological, environmental and industrial sectors. Due to the cost-effectiveness of the solid-state fermentation (SSF) process, it is widely used to produce a broad range of biological products. In this study, optimization of moisture content, temperature, pH, and inoculum size were studied to enhance laccase production ability of Pleurotus sajor-caju in SSF by using One Factor At Time (OFAT) and Response Surface Methodology (RSM). OFAT was used as a baseline study for deducing the experimental design of RSM. The highest production of laccase enzyme (1450 U/g) by Pleurotus sajor-caju on wheat straw was observed at 26°C, 6.0 pH, 72.5 % moisture content, 7.5% inoculum size, 1% fructose and 0.5 % peptone. Unlike the conventional inoculum preparation method, here the inoculum was generated by the spawning method for SSF. The molecular weight of partially purified laccase from Pleurotus sajor-caju was estimated to be around 62 K Da using SDS PAGE. The activity staining of laccase was observed as a zymogram on Native PAGE using ABTS as a substrate. Lignin degradation of wheat straw and its structural disruption due to laccase was observed by Scanning Electron Microscopy (SEM).

Ethanol production from residual lignocellulosic fibers generated through the steam treatment of whole sorghum biomass

Cellulosic ethanol could play a major role in the upcoming circular-economy once the process complexity, low carbohydrate extraction yields and high costs are resolved. To this purpose, different steam-treatment severity factors were employed on whole sweet sorghum biomass, followed by the delignification and hydrolysis of resulted lignocellulose fibers. A modified ASTM International (American Society for Testing and Material) standard cellulose hydrolysis approach as well as a newly developed SACH (Sulfuric Acid Cellulose Hydrolysis) process were used, recovering up to 24.3 wt% of cellulosic carbohydrates. This amounted to a total extractable and constitutive carbohydrate recovery of 51.7 wt% (dry basis) when a mild steam-treatment of whole sorghum biomass and the SACH cellulose hydrolysis were employed. An ethanol potential of 6378 L/ha/year was determined, comparable to values obtained from biomass such as sugarcane in warmer climates, supporting thus the opportunity of implementing this novel approach on a wider scale.

Impact and significance of alkaline-oxidant pretreatment on the enzymatic digestibility of Sphenoclea zeylanica for bioethanol production

Gooseweed (Sphenoclea zeylanica Gaertn.) is a pest on the rice field that has a potential to be a promising substrate for bioethanol production. Dry powdered gooseweed was firstly pretreated with 1% NaOH, following 1% H₂O₂ at variety conditions. The hydrolysis process was set at 50°C for 24-72h with enzyme cellulase (β-glucosidase) while the fermentation process was carried using Saccharomyces cerevisiae TISTR 5020 at 33°C for nine days. The ethanol concentration was recorded for three, five, seven, and nine days using an ebulliometer. The results showed that the treatment with only 1% NaOH for 24h has the highest sugar performance. In regard with hydrolysis, the optimum retention time was at 24h. Lastly, the highest ethanol concentration was achieved at 11.84g/L after five days and a rapid decreasing after seven to nine days was also observed.