Overview of the Process of Enzymatic Transformation of Biomass

Cellulase is an enzyme which depolymerizes the cellulose into glucose. Cellulases are produced by a diverse array of microbes including fungi, bacteria, yeast and actinomycetes. Considerable research for understanding the mechanism of cellulases began in early 1950s because of the significant use of these enzymes in various industries. This review provides a general account structure and availability of lignocellulosic biomass, pretreatment strategies for effective digestion, cellulase producing organisms, cellulase activity assay, and enzymology of cellulose degradation. Cellulase production, optimization, purification and characterization studies in addition to the industrial application of cellulase have also been discussed. At last a brief account of present market scenario of cellulases and future prospects of the study are also taken into account

Detoxification of Copper and Chromium Via Dark Hydrogen Fermentation of Potato Waste by Clostridium butyricum Strain 92

The accumulation of various types of waste containing both organic and inorganic metal-containing compounds is extremely hazardous for living organisms. The possibility of polymer degradation, biohydrogen synthesis, and metal detoxification via the dark fermentation of model potato waste was investigated. For this purpose, the strict anaerobic strain was isolated and identified as Clostridium butyricum. The high efficiency of dark hydrogen fermentation of potatoes with yield of hydrogen in 85.8 ± 15.3 L kg−1 VSpotato was observed. The copperand chromium salts solutions were added to the culture fluid to obtain the concentrations of 50, 100, and 200 mg L−1 Cu(II) and Cr(VI) in the active phase of growth (19 h of cultivation). Metals at a concentration of 200 mg L−1 inhibited the fermentation process the most. The hydrogen yield decreased in 7.2 and 3.6 times to 11.9 ± 2.1 and 23.8 ± 5.6 L kg−1 VSpotato in the presence of 200 mg L−1 Cu(II) and Cr(VI), respectively. The efficiencies of the chromium bioremoval in all variants of the experiment were 100%, and those of copper bioremoval were about 90%. A pure culture of strict anaerobes Clostridium butyricum strain 92 was used for the first time for the detoxification of metals. The presented results confirmed the possibility of this promising strain application for industrial H2 production and the bioremediation of contaminated sites

Increase in efficiency of hydrogen production by optimization of food waste fermentation parameters

The aim of the work was to optimize the ratio of weight of solid (food waste) and liquid (water) phases in order to ensure high efficiency of molecular hydrogen synthesis and degradation of multi-component food waste. Assessment of the efficiency of fermentation process was carried out using colorimetric and potentiometric methods for pH and redox potential measuring, volumetric and chromatographic methods for volume and composition of gas investigation, and mathematical calculations for fermentation parameters determination. The dynamics of hydrogen fermentation of waste in the horizontal reactor using different ratios of solid (food waste) and liquid (water) phases was investigated. The optimization of the ratio of solid and liquid phases was shown to lead to the increase in efficiency of molecular hydrogen synthesis and destruction of waste particles. The ratio of solid and liquid phases 1:3 was determined to be optimal for the effective synthesis of hydrogen as well as for maximum waste decomposition. It provided effective hydrogen fermentation of multi-component food waste and allowed to rationally use material and technical resources. Obtained results are promising for further development of efficient industrial biotechnologies for waste destruction with the simultaneous synthesis of environmentally friendly energy carrier, i.e. molecular hydrogen

Draft Genome Sequences of Six Strains Isolated From the Rhizosphere of Wheat Grown In Cadmium-Contaminated Soil

This study presents high-quality draft genome assemblies of six bacterial strains isolated from the roots of wheat grown in soil contaminated with cadmium. The results of this study will help to elucidate at the molecular level how heavy metals affect interactions between beneficial rhizobacteria and crop plants

Anaerobic Degradation of the Invasive Weed <i>Solidago canadensis</i> L. (<i>goldenrod</i>) and Copper Immobilization by a Community of Sulfate-Reducing and Methane-Producing Bacteria

The weed Solidago canadensis L. poses a global threat to the environment as it spreads uncontrollably on roadsides, in forests, fields, meadows, and farmland. Goldenrod emits toxic substances that suppress other plants on the site, displacing wild ones. Thus, goldenrod conquers huge areas very quickly. The use of herbicides and mechanical methods does not solve the problem of the spontaneous spread of goldenrod. On the other hand, many scientists consider goldenrod as a valuable source of biologically active substances: flavonoids, phenolic compounds, vitamins, etc. In this study, we consider Solidago plants as a promising, free (cheap), and renewable substrate for the production of methane gas. The goal of the study was to identify the main patterns of degradation of the Solidago canadensis L. plant by methane-producing and sulfate-reducing bacteria with methane gas production and simultaneous detoxification of toxic copper. The composition of the gas phase was monitored by gas chromatography. The pH and redox potential parameters were determined potentiometrically; metal concentrations were measured by photometry. The concentration of flavonoids, sugars and phenolic compounds in plant biomass was determined according to well-known protocols. As a result of the study, high efficiencies of methane degradation in the Solidago plant and copper detoxification were obtained. Methane yield has reached the value of 68.2 L kg−1 TS of Solidago canadensis L. biomass. The degradation coefficient (Kd) was also high at 21.4. The Cu(II) was effectively immobilized by methanogens and sulfate reducers during the goldenrod degradation at the initial concentrations of 500 mg L−1. Thus, a new method of beneficial application of invasive plants was presented. The result confirms the possibility of using methanogenic microorganisms to produce methane gas from invasive weeds and detoxification of toxic metals

Increase in efficiency of hydrogen production by optimization of food waste fermentation parameters

The aim of the work was to optimize the ratio of weight of solid (food waste) and liquid (water) phases in order to ensure high efficiency of molecular hydrogen synthesis and degradation of multi-component food waste. Assessment of the efficiency of fermentation process was carried out using colorimetric and potentiometric methods for pH and redox potential measuring, volumetric and chromatographic methods for volume and composition of gas investigation, and mathematical calculations for fermentation parameters determination. The dynamics of hydrogen fermentation of waste in the horizontal reactor using different ratios of solid (food waste) and liquid (water) phases was investigated. The optimization of the ratio of solid and liquid phases was shown to lead to the increase in efficiency of molecular hydrogen synthesis and destruction of waste particles. The ratio of solid and liquid phases 1:3 was determined to be optimal for the effective synthesis of hydrogen as well as for maximum waste decomposition. It provided effective hydrogen fermentation of multi-component food waste and allowed to rationally use material and technical resources. Obtained results are promising for further development of efficient industrial biotechnologies for waste destruction with the simultaneous synthesis of environmentally friendly energy carrier, i.e. molecular hydrogen

A Noxious Weed <i>Ambrosia artemisiifolia</i> L. (Ragweed) as Sustainable Feedstock for Methane Production and Metals Immobilization

Plants of the Ambrosia genus are invasive and cause many ecological problems, including the oppression of the growth of agricultural crops and native plants, land depletion, and the production of strong allergens. The use of weeds as a sustainable feedstock for biogas production, either methane or hydrogen, is a promising way to fulfill the energy needs of the current generation, eliminate the depletion of non-renewable carbon resources, and preserve the ecosystem degradation caused by invasive species impacts. A diversified microbial community was used as inoculum and Ambrosia artemisiifolia L. biomass as a substrate for anaerobic degradation and methane production. In this regard, the development of biotechnological approaches to ragweed degradation will promote the integration of new renewable energy systems. Herein, we have shown the high effectiveness of combining the processes of anaerobic degradation of plant biomass for methane production and detoxification of meal-containing model sewage by a diversified microbial community. Thus, the maximum methane yield was 56.0 L kg−1 TS. The presence of 500 mg L−1 Cu(II) slightly inhibited methane synthesis, and the methane yield was 38.4 L kg−1 TS. In contrast to a diversified microbial community, the natural microbiome of ragweed almost did not synthesize methane and did not degrade plant biomass (Kd = 2.3). Methanogens effectively immobilized Cr(IV), Cu(II), and Fe(III) during ragweed fermentation at initial concentrations of 100–200 mg L−1. The obtained results showed the high effectiveness of applying a diversified microbial community in a sewage treatment plant for the degradation of a noxious plant, Ambrosia artemisiifolia L

Spatial Succession for Degradation of Solid Multicomponent Food Waste and Purification of Toxic Leachate with the Obtaining of Biohydrogen and Biomethane

A huge amount of organic waste is generated annually around the globe. The main sources of solid and liquid organic waste are municipalities and canning and food industries. Most of it is disposed of in an environmentally unfriendly way since none of the modern recycling technologies can cope with such immense volumes of waste. Microbiological and biotechnological approaches are extremely promising for solving this environmental problem. Moreover, organic waste can serve as the substrate to obtain alternative energy, such as biohydrogen (H2) and biomethane (CH4). This work aimed to design and test new technology for the degradation of food waste, coupled with biohydrogen and biomethane production, as well as liquid organic leachate purification. The effective treatment of waste was achieved due to the application of the specific granular microbial preparation. Microbiological and physicochemical methods were used to measure the fermentation parameters. As a result, a four-module direct flow installation efficiently couples spatial succession of anaerobic and aerobic bacteria with other micro- and macroorganisms to simultaneously recycle organic waste, remediate the resulting leachate, and generate biogas

Spatial Succession for Degradation of Solid Multicomponent Food Waste and Purification of Toxic Leachate with the Obtaining of Biohydrogen and Biomethane

A huge amount of organic waste is generated annually around the globe. The main sources of solid and liquid organic waste are municipalities and canning and food industries. Most of it is disposed of in an environmentally unfriendly way since none of the modern recycling technologies can cope with such immense volumes of waste. Microbiological and biotechnological approaches are extremely promising for solving this environmental problem. Moreover, organic waste can serve as the substrate to obtain alternative energy, such as biohydrogen (H2) and biomethane (CH4). This work aimed to design and test new technology for the degradation of food waste, coupled with biohydrogen and biomethane production, as well as liquid organic leachate purification. The effective treatment of waste was achieved due to the application of the specific granular microbial preparation. Microbiological and physicochemical methods were used to measure the fermentation parameters. As a result, a four-module direct flow installation efficiently couples spatial succession of anaerobic and aerobic bacteria with other micro- and macroorganisms to simultaneously recycle organic waste, remediate the resulting leachate, and generate biogas