Improvement of Hydrogen Production during Anaerobic Fermentation of Food Waste Leachate by Enriched Bacterial Culture Using Biochar as an Additive

It has become urgent to develop cost-effective and clean technologies for the rapid and efficient treatment of food waste leachate, caused by the rapid accumulation of food waste volume. Moreover, to face the energy crisis, and to avoid dependence on non-renewable energy sources, the investigation of new sustainable and renewable energy sources from organic waste to energy conversion is an attractive option. Green energy biohydrogen production from food waste leachate, using a microbial pathway, is one of the most efficient technologies, due to its eco-friendly nature and high energy yield. Therefore, the present study aimed to evaluate the ability of an enriched bacterial mixture, isolated from forest soil, to enhance hydrogen production from food waste leachate using biochar. A lab-scale analysis was conducted at 35 °C and at different pH values (4, no adjustment, 6, 6.5, 7, and 7.5) over a period of 15 days. The sample with the enriched bacterial mixture supplemented with an optimum of 10 g/L of biochar showed the highest performance, with a maximum hydrogen yield of 1620 mL/day on day three. The total solid and volatile solid removal rates were 78.5% and 75% after 15 days, respectively. Acetic and butyrate acids were the dominant volatile fatty acids produced during the process, as favorable metabolic pathways for accelerating hydrogen production

Genome Insight and Description of Previously Uncultured N2-Fixing Bacterium Rhizobium terricola sp. nov., Isolated from Forest Rhizospheric Soil by Using Modified Culture Method

A bacterial strain S-51T was isolated from rhizospheric forest soil at Kyonggi University during the study of previously uncultured bacterium. The phylogenetic analysis was based on 16S rRNA gene sequences that indicated that strain S-51T belonged to the genus Rhizobium within the family Rhizobiaceae. The closest members of strain S-51T were Rhizobium naphthalenivorans TSY03bT (98.2% sequence similarity) and Rhizobium selenitireducens ATCC BAA-1503T (98.1%). The sequence similarities of other members were <97.7%. The sole respiratory quinone was Q-10 and the major polar lipids were phosphatidylethanolamine, diphosphatidylglycerol, phosphatidylcholine, and unidentified glycolipid. The principal fatty acids were summed feature 8 (C18:1ω7c and/or C18:1ω6c), cyclo-C19:0ω8c, and C18:0. The DNA G+C content was 63.1 mol%. The genome was 4930044 bp long and contained N2-fixing genes, such as fixF, ntrC, and ptsN, in addition to respiratory nitrate reductase genes, such as narC, narG, narH, narI, and narJ. The average nucleotide identity (ANIu), average amino acid identity (AAI), and digital DNA-DNA hybridization (dDDH) relatedness between strain S-51T and phylogenetically related species were ≤82.6, ≤83.6 and ≤25.3%, respectively, much lower than the species delineation thresholds. Based on the polyphasic taxonomic study, strain S-51T represents a new species in the genus Rhizobium, for which the name Rhizobium terricola is proposed. The type strain is S-51T (=KACC 19117T = KEMB 9005-539T = NBRC 112711T)

Biodegradation of Methylene Blue Using a Novel Lignin Peroxidase Enzyme Producing Bacteria, Named Bacillus sp. React3, as a Promising Candidate for Dye-Contaminated Wastewater Treatment

The emission of methylene blue (MB) from common industries causes risks to human health by making clean drinking water unavailable and hampering environmental safety. A biological approach offering a more cost-efficient and sustainable alternative solution has been studied and demonstrated to be significantly effective for the removal of MB using promising microbial isolates. Therefore, this study targeted bacterial candidates, namely Bacillus sp. React3, isolated from soil with the potential to decolorize MB. The phenogenic identification of strain React3 was performed by 16S rRNA sequencing, showing a similarity of 98.86% to Bacillus velezensis CR-502T. The ability of this bacterial strain to decolorize MB was proven through both the lignin peroxidase efficiency and accumulation in the biomass of the living cells. MB removal was determined by the reduction in the maximum absorption at a wavelength of 665 nm, which was observed to be up to 99.5% after 48 h of incubation. The optimal conditions for the MB degradation of strain React3 were pH 7, 35 °C, static, 4% inoculum, and 1000 mg/L of MB, with tryptone as a carbon source and yeast extract as a nitrogen source

Investigation of Lipolytic-Secreting Bacteria from an Artificially Polluted Soil Using a Modified Culture Method and Optimization of Their Lipase Production

Compared to lipases from plants or animals, microbial lipases play a vital role in different industrial applications and biotechnological perspectives due to their high stability and cost-effectiveness. Therefore, numerous lipase producers have been investigated in a variety of environments in the presence of lipidic carbon and organic nitrogen sources. As a step in the development of cultivating the unculturable functional bacteria in this study, the forest soil collected from the surrounding plant roots was used to create an artificially contaminated environment for lipase-producing bacterial isolation. The ten strongest active bacterial strains were tested in an enzyme assay supplemented with metal ions such as Ca2+, Zn2+, Cu2+, Fe2+, Mg2+, K+, Co2+, Mn2+, and Sn2+ to determine bacterial tolerance and the effect of these metal ions on enzyme activity. Lipolytic bacteria in this study tended to grow and achieved a high lipase activity at temperatures of 35–40 °C and at pH 6–7, reaching a peak of 480 U/mL and 420 U/mL produced by Lysinibacillus PL33 and Lysinibacillus PL35, respectively. These potential lipase-producing bacteria are excellent candidates for large-scale applications in the future

Bacterial Biosorbents, an Efficient Heavy Metals Green Clean-Up Strategy: Prospects, Challenges, and Opportunities

Rapid industrialization has led to the pollution of soil and water by various types of contaminants. Heavy metals (HMs) are considered the most reactive toxic contaminants, even at low concentrations, which cause health problems through accumulation in the food chain and water. Remediation using conventional methods, including physical and chemical techniques, is a costly treatment process and generates toxic by-products, which may negatively affect the surrounding environment. Therefore, biosorption has attracted significant research interest in the recent decades. In contrast to existing methods, bacterial biomass offers a potential alternative for recovering toxic/persistent HMs from the environment through different mechanisms for metal ion uptake. This review provides an outlook of the advantages and disadvantages of the current bioremediation technologies and describes bacterial groups, especially extremophiles with biosorbent potential for heavy metal removal with relevant examples and perspectives

Biodegradation of Methylene Blue Using a Novel Lignin Peroxidase Enzyme Producing Bacteria, Named <i>Bacillus</i> sp. React3, as a Promising Candidate for Dye-Contaminated Wastewater Treatment

The emission of methylene blue (MB) from common industries causes risks to human health by making clean drinking water unavailable and hampering environmental safety. A biological approach offering a more cost-efficient and sustainable alternative solution has been studied and demonstrated to be significantly effective for the removal of MB using promising microbial isolates. Therefore, this study targeted bacterial candidates, namely Bacillus sp. React3, isolated from soil with the potential to decolorize MB. The phenogenic identification of strain React3 was performed by 16S rRNA sequencing, showing a similarity of 98.86% to Bacillus velezensis CR-502T. The ability of this bacterial strain to decolorize MB was proven through both the lignin peroxidase efficiency and accumulation in the biomass of the living cells. MB removal was determined by the reduction in the maximum absorption at a wavelength of 665 nm, which was observed to be up to 99.5% after 48 h of incubation. The optimal conditions for the MB degradation of strain React3 were pH 7, 35 °C, static, 4% inoculum, and 1000 mg/L of MB, with tryptone as a carbon source and yeast extract as a nitrogen source

Purification and Characterization of Strong Simultaneous Enzyme Production of Protease and α-Amylase from an Extremophile-<i>Bacillus</i> sp. FW2 and Its Possibility in Food Waste Degradation

Microbial enzymes such as protease and amylase are valuable enzymes with various applications, widely investigated for their applications in degradation of organic waste, biofuel industries, agricultural, pharmaceuticals, chemistry, and biotechnology. In particular, extremophiles play an important role in biorefinery due to their novel metabolic products such as high value catalytic enzymes that are active even under harsh environmental conditions. Due to their potentials and very broad activities, this study isolated, investigated, and characterized the protease- and amylase-producing bacterial strain FW2 that was isolated from food waste. Strain FW2 belongs to the genus Bacillus and was found to be closest to Bacillus amyloliquefaciens DSM 7T with a similarity of 99.86%. This strain was able to degrade organic compounds at temperatures from −6 °C to 75 °C (but weak at 80 °C) under a wide pH range (4.5–12) and high-salinity conditions up to 35% NaCl. Maximum enzyme production was obtained at 1200 ± 23.4 U/mL for protease and 2400 ± 45.8 U/mL for amylase for 4 days at pH 7–7.5, 40–45 °C, and 0–10% NaCl. SDS-PAGE analysis showed that the molecular weights of purified protease were 28 kDa and 44 kDa, corresponding to alkaline protease (AprM) and neutral protease (NprM), respectively, and molecular weight of α-amylase was 55 kDa. Degradation food waste was determined after 15 days, observing a 69% of volume decrease. A potential commercial extremozyme-producing bacteria such as strain FW2 may be a promising contributor to waste degradation under extreme environmental conditions