This study aimed to conduct the isolation, screening and identification of bacteria with a high level of cellulolytic activity from the muddy sediments of mangrove swamps in Thailand. One hundred and ninety aquatic bacterial isolates were isolated from different muddy sediments and eighty one isolates were determined to be cellulolytic bacteria. The cellulolytic bacterium identified as Bacillus cereus JD0404 showed maximum hydrolysis activity on carboxymethylcellulose agar plates. Its cellulolytic performance for CMCase activity, Avicelase activity and β-glucosidase activity was 1.778±0.003U/mL, 0.079±0.001U/mL and 0.048±0.002U/mL, respectively. The optimum temperature and pH for the enzyme activity were determined to be 50°C and 7.0 respectively. The cellulolytic activity was greatly enhanced by Mn2+ and considerably inhibited by EDTA and toluene. Preliminary bioconversion application showed that the B. cereus JD0404 could be used for the hydrolysis of cellulose-based biomass. This study demonstrated a feasible bacterium for environmentally friendly industries and biotechnology

The global reliance on fossil fuels has caused severe environmental challenges, emphasizing the urgent need for sustainable and renewable energy sources. Bioethanol production from lignocellulosic biomass has emerged as a promising alternative due to its abundance, renewability, and carbon-neutral footprint. However, its economic feasibility remains a major obstacle owing to high production costs, particularly those associated with low ethanol titers and the energy-intensive distillation process costs for low titers. High-solid loading processes (≥15% w/w or w/v) have demonstrated potential to overcome these limitations by minimizing water and solvent consumption, enhancing sugar concentrations, increasing ethanol titers, and lowering downstream processing cost. Nevertheless, high-solid loading also introduces operational bottlenecks, such as elevated viscosity, poor mixing, and limited mass and heat transfer, which hinder enzymatic hydrolysis efficiency. This review critically examines emerging pretreatment and enzymatic hydrolysis strategies tailored for high-solid loading conditions. It also explores techniques that improve sugar yields and conversion efficiency while addressing key technical barriers, including enzyme engineering, process integration, and optimization. By evaluating these challenges and potential mitigation strategies, this review provides actionable insights to intensify lignocellulosic ethanol production and advance the development of scalable, cost-effective biorefinery platforms.

Wastewater released from textile and dye-based industries is one of the major concerns for human and aquatic beings. Biological decolorization using ligninolytic bacteria has been considered as an effective and alternative approach for the treatment of dyeing wastewater. This study aimed to assess the isolation, characterization and application of soil bacteria isolated from mangrove wetlands in Thailand. Four active bacteria were genetically identified and designated as Klebsiella pneumoniae strain RY10302, Enterobacter sp. strain RY10402, Enterobacter sp. strain RY11902 and Enterobacter sp. strain RY11903. They were observed for ligninolytic activity and decolorization of nine reactive dyes under experimental conditions. All bacteria exhibited strong decolorization efficiency within 72 h of incubation at 0.01% (w/v) of reactive dyes. The decolorization percentage varied from 20% (C.I. Reactive Red 195 decolorized by K. pneumoniae strain RY10302) to 92% (C.I. Reactive Blue 194 decolorized by Enterobacter sp. strain RY11902) in the case of bacterial monoculture, whereas the decolorization percentage for a mixed culture of four bacteria varied from 58% (C.I. Reactive Blue 19) to 94% (C.I. Reactive Black 1). These findings confer the possibility of using these bacteria for the biological decolorization of dyeing wastewater.

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Klinfoong R, Thummakasorn C, Ungwiwatkul S, Boontanom P, Chantarasiri A. 2022. Diversity and activity of amylase-producing bacteria isolated from mangrove soil in Thailand. Biodiversitas 23: 5519-5531. Mangrove forests are a potential ecosystem for the isolation of various economic enzymes derived from mangrove-associated bacteria. The knowledge of amylase-producing bacteria isolated from mangrove forests in the Southeast Asian region has been scarce. This study aimed to investigate the isolation, genetic identification, and activity characterization of amylase-producing bacteria from mangrove soils in Thailand. The amylase-producing bacteria isolated from mangrove soils in the present were genetically belong to the genera Bacillus, Desulfurella, Peribacillus, Priestia, and Pseudomonas. Several amylase-producing bacteria such as Bacillus proteolyticus, Desulfurella, Pseudomonas entomophila, and Pseudomonas putida found in this study have hardly ever been reported. The Bacillus paralicheniformis strain DNP0507 was the most active amylolytic bacterium with 2.395 ± 0.133 U/mg of amylase activity. The optimum temperature and pH for amylolytic activity were determined to be 50°C at a pH of 7.0 with a thermal stability range of 20-60°C at a neutral pH of 7.0-8.0. The enzyme activity was significantly enhanced by Cu2+, Co2+, and Pb2+ and was inhibited considerably by a chelating agent EDTA. Finally, the most active amylolytic B. paralicheniformis strain DNP0507 could be applied in baking industries, food industries, and starchy waste valorization.

One impediment of large-scale biofuel production from lignocellulosic biomass is the insufficiency of cellulolytic microorganisms that can overcome extreme conditions during the industrial process. This study emphasized the isolation of a novel efficient cellulolytic bacterium. A new Bacillus methylotrophicus RYC01101, isolated from ruminant feces in Thailand, produced a hydrolysis capacity greater than that of known cellulolytic bacteria (Cellulomonas sp.). Cellulase activities were investigated on CMCase activity and FPase activity by 0.230±0.004 and 0.080±0.007 U/mL, respectively. B. methylotrophicus RYC01101 was co-cultured with Saccharomyces cerevisiae TISTR 5111 for bioethanol production. The productivity of the bioethanol was 1.38±0.40 g/L after 120 hours of fermentation. Moreover, B. methylotrophicus RYC01101 could be grown in the presence of 10% (w/v) NaCl, which could be applied in the pretreatment step of biofuel production. This study was the first report on cellulolytic activity and the halotolerant ability of B. methylotrophicus.