Microbial Enzymes Research Articles

Effects of Land-Use Type and Salinity on Soil Carbon Mineralization in Coastal Areas of Northern Jiangsu Province

Sea level rise due to glacier melting caused by climate warming is a major global challenge, but the mechanism of the effect of salinity on soil carbon (C) mineralization in different land types is not clear. The pathways by which salinity indirectly affects soil carbon mineralization rates need to be investigated. Whether or not the response mode is consistent among different land-use types, as well as the intrinsic links and interactions between soil microbial resource limitation, environmental stress, microbial extracellular enzyme activity, and soil carbon mineralization, remain to be demonstrated. In this paper, three typical land-use types (wetland, forest, and agroforestry) were selected, and different salinity levels (0‰, 3‰, 6‰, and 32‰) were designed to conduct a 125-day laboratory incubation experiment to determine the soil CO2 release rate, soil physicochemical properties, and soil enzyme activities, and to correlate C mineralization with biotic and abiotic factors. A correlation analysis of soil physical and chemical properties, extracellular enzyme activities, and carbon mineralization rates was conducted to investigate their intrinsic linkages, and a multiple linear regression of C mineralization at different sites was performed to explore the variability of mineralization among different site types. Structural equation models were established in the pre- and post-incubation stages to study the pathways of soil C mineralization at different incubation times, and the mechanism of mineralization was further verified by enzyme stoichiometry. The results showed that, at the end of 125 days of incubation, the 32‰ salinity addition reduced the cumulative mineralization of forest and agroforestry types by 28.41% and 34.35%, respectively, compared to the 0‰ salinity addition. Soil C mineralization in the three different land-use types was highly correlated with the active C fractions of readily oxidizable C (ROC), dissolved organic C, and microbial biomass C (MBC) in the soil, with the standardized coefficients of multivariate linear regression reaching 0.67 for MBC in the wetland and −0.843 for ROC in the forest. Under long-term salinity additions, increased salinity would reduce the microbial respiratory quotient value by inhibiting β-glucosidase activity, thus indirectly affecting the rate of CO2 release. With added salinity, the mineralization of non-saline soil was more susceptible to the inhibitory effect of salinity, whereas the mineralization of salinized soil was more controlled by soil C pools.

No tillage and leguminous cover crop improve soil quality in a typical rainfed Mediterranean system

Soil and crop management influence soil organic carbon (SOC), chemical composition, and overall soil quality. In a Mediterranean region, a study initiated in 1994 examined the long-term effects of conventional tillage (CT) versus no-tillage (NT) practices. Initially focusing on continuous durum wheat cultivation until 2009, the experiment later introduced a two-year rotation of durum wheat and Vicia faba L. cover crops in half of the CT and NT fields. SOC was monitored from 2008 to 2018, while microbial biomass (as dsDNA), soluble nitrogen (N), and enzyme activities (EAs) were monitored from 2011 to 2014 to evaluate the rotation's impact.
 Between 2009 and 2018, CT yields were on average 15% higher than NT, especially during high rainfall years. NT significantly increased SOC content in the 0-30 cm soil layer, along with higher levels of soluble N, dsDNA, and EAs at 0-10 cm depth. NT led to a 23% and 10% increase in SOC stock and SOC stock per equivalent soil mass respectively compared to CT. EAs increased by over 50% under NT, indicating enhanced biological activity. The SOC increase due to NT was limited to the top 10 cm, with a decrease at deeper depths (up to 50 cm). Introducing cover crops over four years did not yield significant impacts, suggesting the need for a longer period to observe noticeable effects.
 Overall, adopting NT practices resulted in higher SOC concentration, enhanced soil biological activity, and improved biogeochemical cycles, emphasizing the positive impact of no-tillage on soil health and sustainability.

Valorization of dairy effluent for the conversion of microbial fibrinolytic enzymes for environment management and bio-medical applications

Valorization of dairy effluent for the conversion of microbial fibrinolytic enzymes for environment management and bio-medical applications

Oral tryptophan activates duodenal aryl hydrocarbon receptor in healthy subjects: a crossover randomized controlled trial.

Background and Aims: Tryptophan is an essential amino acid transformed by host and gut microbial enzymes into metabolites that regulate mucosal homeostasis through Aryl hydrocarbon receptor (AhR) activation. Alteration of tryptophan metabolism has been associated with chronic inflammation, however whether tryptophan supplementation affects the metabolite repertoire and AhR activation under physiologic conditions in humans, is unknown. Methods: We performed a randomized, double blind, placebo-controlled, crossover study in 20 healthy volunteers. Subjects on a low tryptophan background diet were randomly assigned to a 3-week L-tryptophan supplementation (3 g/day) or placebo, and after a 2-week washout switched to opposite interventions. We assessed gastrointestinal and psychological symptoms by validated questionnaires, AhR activation by cell reporter assay, tryptophan metabolites by liquid chromatography and high-resolution mass spectrometry, cytokine production in isolated monocytes by ELISA and microbiota profile by 16S rRNA Illumina technique. Results: Oral tryptophan supplementation was well tolerated, with no changes in gastrointestinal or psychological scores. Compared with placebo, tryptophan increased AhR activation capacity by duodenal contents, but not by feces. This was paralleled by higher urinary and plasma kynurenine metabolites and indoles. Tryptophan had a modest impact on fecal microbiome profiles, and no significant effect on cytokine production. Conclusions: At the doses used in this study, oral tryptophan supplementation in humans induces microbial indole and host kynurenine metabolic pathways in the small intestine, known to be immunomodulatory. The results should prompt tryptophan intervention strategies in inflammatory conditions of the small intestine where the AhR pathway is impaired.

Response of bacterial communities, enzyme activities and dynamic changes of soil organic nitrogen fractions to six-year different application levels of biochar retention in Northeast China

Composition and availability of soil organic nitrogen play a key role in soil N retention and supply. The application of traditional chemical fertilizers can improve soil production and crop yields. However, it also leads to low N utilization efficiency and soil solidification. Previous studies have shown that fertilizers added with biochar can improve soil fertility and facilitate soil nutrient transformation by regulating soil biological indicators. However, whether biochar used with fertilizers can promote nutrient cycling in the long term, which remains to be tested. Therefore, this study aims to explore the long-term effects of biochar with different levels used with fertilizers on soil fertility, N supply potential of organic N, and microbial communities, thus, providing a theoretical reference for the rational management of biochar applications. In this study, a field experiment was carried out from 2013 to 2018 assess dynamic changes in organic N fractions and diversity and richness of microbial communities under the impacts of chemical fertilizers combined with different levels of biochar. Biochar with no amendment (CK), biochar with 15.75 t ha−1 (BC1), biochar with 31.5 t ha−1 (BC2), and biochar with 47.25 t ha−1 (BC3) are four biochar levels that were tested in this study. The results show that compared with CK, those other three biochar levels can increase soil organic matter, C/N, and pH values. Acid-hydrolysable N (AHN) makes a major contribution to organic N in soil. Biochar retention for six years has significantly affected AHN levels, as well as its four fractions, namely, amino acid N (AAN), acid-hydrolysable ammonium N (AN), amino sugar N (ASN), and hydrolysable unknown N (HUN). Some vital biological characteristics, with which each AHN fraction is primarily regulated, can be altered with the application of biochar. That is, AAN is mainly controlled by enriched Verrucomicrobia, Cyanobacteria, Glucosylbacteria, and Nitrospira, and reduced soil urease, while AN is mainly controlled by enriched Verrucomicrobia, Bacteroidetes, Gemmatimonadetes, Acidobacteria, and Proteobacteria. ASN is regulated by enriched Acidobacteria and depleted soil protease, while HUN is regulated by Gemmatimonadetes and enriched soil nitrate reductase. It has been found that microbial and soil enzyme activities are involved in N cycle processes, indicating that the formation of AHN fractions is closely associated with biochar-induced specific microbial and enzyme activities. This study has provided new insights into the influences of biochar with different levels on distribution of soil organic N fractions, and shifts in soil enzyme activities and microbial communities.

Effects of the combined application of livestock manure and plant residues on soil organic carbon sequestration in the southern Loess Plateau of China

Increasing soil organic carbon (SOC) sequestration enhances the stability and productivity of agricultural ecosystems. Organic material application is a direct and effective way to maintain and improve SOC sequestration. However, currently, there is little knowledge on efficient practices for combined organic material application to improve SOC sequestration. In this study, we evaluated the effect of three organic materials alone or in combination on SOC sequestration in a 4-year field experiment. Eight treatments were included: control (CK, conventional chemical fertilizer), green manure (G), straw (S), decomposed sheep manure (M), green manure plus straw (GS), green manure plus sheep manure (GM), straw plus sheep manure (SM), green manure, and straw plus sheep manure (GSM). In 2020, decomposed sheep manure application (M, SM, GM and GSM) resulted in the greatest cumulative SOC sequestration (9.5–10.8 Mg C ha−1), followed by those in treatments S (6.1 Mg C ha−1) and GS (6.9 Mg C ha−1). The SOC sequestration efficiency in the M treatment (44.8 %) was greater than that in the others (15.2–34.8 %). A random forest model revealed that organic material quantity and quality, enzyme activity, and microbial community composition were the primary factors determining SOC sequestration. Sheep manure application increased SOC sequestration by increasing lignin quantity and proportion. Incorporating green manure and straw return enhanced SOC sequestration by promoting microbial growth and increasing soil C-acquiring enzyme activity. However, interactions between sheep manure and plant residues resulted in decreases in SOC sequestration efficiency compared with sheep manure application alone. This is because combined fertilization stimulated microbial growth and enzyme activity, causing changes in microbial community structure and accelerating organic material and SOC decomposition. Thus, we do not recommend combining livestock manure with straw or green manure to improve SOC sequestration and soil quality in the southern Loess Plateau.

Sustainable Solutions: Reviewing the Future of Textile Dye Contaminant Removal with Emerging Biological Treatments

Synthetic dyes, exceeding 100,000 types on the market and produced at a global scale of over 700,000 tons annually, are extensively used in the textile industry. This industry, a leading contributor to water contamination, relies on dyes like reactive, azo, anthraquinone, and triphenylmethane, resulting in substantial water usage and significant effluent generation. A significant modern challenge is the pollution caused by dye-mixed wastewater, releasing hazardous chemicals into water bodies and posing threats to ecosystems, plants, and human health. Traditionally, physicochemical techniques have addressed textile dye-containing wastewater, but their drawbacks, including cost, inefficiency, and potential secondary pollution, have steered attention towards biological alternatives. Utilizing microorganisms and enzymes, these biological methods, such as microbial cell enzyme immobilization, the biofilm technique, bioreactors, biofuel/bioelectricity production, and genetic engineering, have emerged as promising, cost-effective, and environmentally friendly solutions for efficient dye removal from wastewater. This review paper specifically highlights advanced biological techniques and emphasizes their efficacy in addressing the challenges posed by synthetic textile dyes. Through a systematic review of recent research papers, published results, and observations, this review paper provides insights into emerging biological treatment strategies for effectively removing synthetic textile dyes and contaminants from wastewater.

Biochemical properties and hydrolytic activity in the nutria (Myocastor coypus) digestive tract

Current understanding of site-specific digestion of carbohydrates in mammals is that whereas starch can be degraded by mammalian enzymes, other complex carbohydrates (e.g. pectin, inulin, xylan or cellulose) are typically digested by the enzymes of symbiotic microbes. To test whether the previously reported presence of complex carbohydrate-digesting enzymes in the small intestine of sheep represent actual small intestinal enzyme activity or just outflux of microbial enzymes from the forestomach, we applied the same methodology of isolating enzymes from gastrointestinal contents and applying them in vitro to test substrates in nutria (Myocastor coypus), a hindgut-fermenting rodent without a forestomach. No enzymatic activity against carbohydrates was detected in the stomach, excluding an effect of coprophagy on the presence of the investigated enzymes. While – as expected – starch digestion was highest in the small intestine, and that of the other carbohydrates was highest in the caecum, there was nevertheless detectable enzymatic activity against pectin, inulin, xylan and cellulose in the small intestine. Further investigations notwithstanding, we suggest that these results indicate a certain degree of unspecific carbohydrase activity by small intestinal enzymes that plays no relevant role in vivo due to the short residence time of digesta in the small intestine.

The Impact of Combining Robinia pseudoacacia Leaves and Corn Straw on Soil Carbon Content and Corn Yield in Loess Plateau

In the agroforestry system, the organic matter in the farmland and natural ecosystem enters the farmland soil in a mixed form to improve soil fertility and carbon pool quality. However, it is unclear how soil microbial carbon-degrading enzyme activity responds to carbon dynamics in this process. Therefore, we took farmland in the Loess Plateau as the research object, combining the application of corn straw and Robinia pseudoacacia leaves in a mass ratio of 4:0, 3:1, 2:2, 1:3, and 0:4 for returning to the field. We measured corn grain yield, carbon emission, organic carbon pool component content, and carbon-degrading enzyme activity of the farmland. The results showed that combining corn straw and Robinia pseudoacacia leaves had a significant impact on soil organic carbon components (readily oxidizable organic carbon and recalcitrant organic carbon), carbon-degrading enzymes (polyphenol oxidase, peroxidase, and cellobiohydrolase), and cumulative carbon emissions. The trend of different indicators in different treatments during the corn growth period was similar. We found that soil carbon emissions were closely related to ROC and soil oxidase activity, while soil carbon content was closely related to soil hydrolase activity. Compared to not returning straw to the field, the corn straw and Robinia pseudoacacia leaves returned to the field in a mass ratio of 1:3(Y1C3) can increase corn grain yield by 32.04%. The Y1C3 treatment has the highest soil carbon content and the lowest crop carbon emission efficiency. Soil water content plays a crucial role in the process of carbon pool transformation driven by soil carbon-degrading enzymes. In conclusion, soil carbon dynamics are closely related to the activity of soil carbon-degrading enzymes. Combining the application of corn straw and Robinia pseudoacacia leaves may be a more suitable farming measure for fragile habitats in the Loess Plateau than other solutions.

A Greener Approach to Spinach Farming: Drip Nutrigation with Biogas Slurry Digestate

To achieve higher crop yields and maintain environmental conservation, it is imperative to adopt novel agricultural methods that improve both the quantity and quality of produce. The following study focused on investigating the effectiveness of integrated use of biogas slurry and inorganic nutrigation on spinach growth and nutrient uptake through drip irrigation. A field experiment was conducted using a split-plot design; spinach was cultivated with seven different treatments: biogas slurry nutrigation (BSN) (T1), integrated inorganic + organic nutrigation: 40% Recommended dose of fertilizer (RDF) + BSN (T2), 60% RDF + BSN (T3), 80% RDF + BSN (T4), 100% RDF (T5), slurry broadcasting (SB) (T6), and control (T7). The results showed that spinach grown with (T4) 80% RDF + BSN exhibited optimum plant height and leaf count compared to spinach under other treatments and was at par with T5 100% RDF for crop parameters. T5 treated plants demonstrated the longest roots, followed by T4 treated plants. The highest recorded yield of 5.72 tons ha−1 was achieved in treatment T5 with 100% RDF, followed closely by T4 with 80% RDF + BSN at 5.52 tons ha−1 and T3 with 60% RDF + BSN at 5.36 tons ha−1. These three treatments exhibited comparable yields, showcasing the effectiveness of incorporating biogas slurry nutrigation in conjunction with inorganic fertilizer for achieving high spinach yields. In terms of macronutrient content in spinach leaves, significant differences were found for nitrogen (N), phosphorus (P), and potassium (K) contents. Incorporating biogas slurry into the soil modified microbial enzyme activities, specifically dehydrogenase and phosphatase. Normally, alkaline phosphatase shows greater activity than acidic phosphatase, but the addition of biogas slurry equalized the enzymatic activity of both, establishing a harmonized enzymatic profile. Our results suggest that fertilizing spinach with integrated biogas slurry nutrigation (if properly filtered) + inorganic nutrigation through drip nutrigation is a viable strategy for improving the morphological parameters and productivity of spinach while also contributing to environmental preservation and a reduction in production costs.

Recent progress of atmospheric and room-temperature plasma as a new and promising mutagenesis technology.

At present, atmospheric and room-temperature plasma (ARTP) is regarded as a new and powerful mutagenesis technology with the advantages of environment-friendliness, operation under mild conditions, and fast mutagenesis speed. Compared with traditional mutagenesis strategies, ARTP is used mainly to change the structure of microbial DNA, enzymes, and proteins through a series of physical, chemical, and electromagnetic effects with the organisms, leading to nucleotide breakage, conversion or inversion, causing various DNA damages, so as to screen out the microbial mutants with better biological characteristics. As a result, in recent years, ARTP mutagenesis and the combination of ARTP with traditional mutagenesis have been widely used in microbiology, showing great potential for application. In this review, the recent progress of ARTP mutagenesis in different application fields and bottlenecks of this technology are systematically summarized, with a view to providing a theoretical basis and technical support for better application. Finally, the outlook of ARTP mutagenesis is presented, and we identify the challenges in the field of microbial mutagenesis by ARTP.

The synchronicity of bloom-forming cyanobacteria transcription patterns and hydrogen peroxide dynamics

Hydrogen peroxide is a reactive oxygen species (ROS) naturally occurring at low levels in aquatic environments and production varies widely across different ecosystems. Oxygenic photosynthesis generates hydrogen peroxide as a byproduct, of which some portion can be released to ambient water. However, few studies have examined hydrogen peroxide dynamics in relation to cyanobacterial harmful algal blooms (cHABs). A year-long investigation of algal succession and hydrogen peroxide dynamics was conducted at the Caloosahatchee River, Florida, USA. We aimed to identify potential biological mechanisms responsible for elevated hydrogen peroxide production during cHAB events through the exploration of the freshwater microbial metatranscriptome. Hydrogen peroxide concentrations were elevated from February to September of 2021 when cyanobacteria were active and abundant. We observed one Microcystis cHAB event in spring and one in winter. Both had distinct nutrient uptake and cyanotoxin gene expression patterns. While meaningful levels of microcystin were only detected during periods of elevated hydrogen peroxide, cyanopeptolin was by far the most expressed cyanotoxin during the spring bloom when hydrogen peroxide was at its yearly maxima. Gene expressions of five microbial enzymes (Rubisco, superoxide dismutase, cytochrome b559, pyruvate oxidase, and NADH dehydrogenase) positively correlated to hydrogen peroxide concentrations. Additionally, there was higher nitrogen-fixing gene (nifDKH) expression by filamentous cyanobacteria after the spring bloom but no secondary bloom formation occurred. Overall, elevated environmental hydrogen peroxide concentrations were linked to cyanobacterial dominance and greater expression of specific enzymes in the photosynthesis of cyanobacteria. This implicates cyanobacterial photosynthesis and growth results in increased hydrogen peroxide generation as reflected in measured environmental concentrations.

Advances in microbial exoenzymes bioengineering for improvement of bioplastics degradation

Plastic pollution has become a major global concern, posing numerous challenges for the environment and wildlife. Most conventional ways of plastics degradation are inefficient and cause great damage to ecosystems. The development of biodegradable plastics offers a promising solution for waste management. These plastics are designed to break down under various conditions, opening up new possibilities to mitigate the negative impact of traditional plastics. Microbes, including bacteria and fungi, play a crucial role in the degradation of bioplastics by producing and secreting extracellular enzymes, such as cutinase, lipases, and proteases. However, these microbial enzymes are sensitive to extreme environmental conditions, such as temperature and acidity, affecting their functions and stability. To address these challenges, scientists have employed protein engineering and immobilization techniques to enhance enzyme stability and predict protein structures. Strategies such as improving enzyme and substrate interaction, increasing enzyme thermostability, reinforcing the bonding between the active site of the enzyme and substrate, and refining enzyme activity are being utilized to boost enzyme immobilization and functionality. Recently, bioengineering through gene cloning and expression in potential microorganisms, has revolutionized the biodegradation of bioplastics. This review aimed to discuss the most recent protein engineering strategies for modifying bioplastic-degrading enzymes in terms of stability and functionality, including enzyme thermostability enhancement, reinforcing the substrate binding to the enzyme active site, refining with other enzymes, and improvement of enzyme surface and substrate action. Additionally, discovered bioplastic-degrading exoenzymes by metagenomics techniques were emphasized.

Decoupling between the genetic potential and the metabolic regulation and expression in microbial organic matter cleavage across microbiomes.

Omics tools are used to explore adaptive mechanism of microbes in diverse systems, but the advantages and limitations of different omics tools remain skeptical. Here, we reported distinct profiles in microbial secretory enzyme composition revealed by different omics methods. In general, the predicted function from metagenomic analysis decoupled from the expression of corresponding transcripts/proteins. Linking omics results to taxonomic origin, functional capability, substrate specificity, secretion preference, and enzymatic activity measurement suggested the substrate's source, concentration and stoichiometry impose strong filtering on the expression of extracellular enzymes, which may overwrite the genetic potentials. Our results present an integrated perspective on the need for multi-dimensional characterization of microbial adaptation in a changing environment.

Mycorrhizosphere bacteria inhibit greenhouse gas emissions from microplastics contaminated soil by regulating soil enzyme activities and microbial community structure

Microplastics (MPs) accumulation in terrestrial ecosystems can affect greenhouse gases (GHGs) production by altering microbial and soil structure. Presently, research on the MPs effect on plants is not consistent, and underlying molecular mechanisms associated with GHGs are yet unknown. For the first time, we conducted a microcosm study to explore the impact of MPs addition (Raw vs. aged) and Trichoderma longibrachiatum and Bacillus subtilis inoculation (Sole vs. combination) on GHGs emission, soil community structure, physiochemical properties, and enzyme activities. Our results indicated that the addition of aged MPs considerably enhanced the GHGs emissions (N2O (+16%) and CO2 (+21%), respectively), C and N cycling gene expression, microbial biomass carbon, and soil physiochemical properties than raw MPs. However, the soil microbial community structure and enzyme activities were enhanced in raw MPs added treatments, irrespective of the MPs type added to soil. However, microbial inoculation significantly reduced GHGs emission by altering the expression of C and N cycling genes in both types of MPs added treatments. The soil microbial community structure, enzymes activities, physiochemical properties and microbial biomass carbon were enhanced in the presence of microbial inoculation in both type of MPs. Among sole and combined inoculation of Trichoderma and Bacillus subtilis, the co-applied Trichoderma and Bacillus subtilis considerably reduced the GHGs emission (N2O (−64%) and CO2 (−61%), respectively) by altering the expression of C and N cycling genes regardless of MPs type used. The combined inoculation also enhanced soil enzyme activities, microbial community structure, physiochemical properties and microbial biomass carbon in both types of MPs treatment. Our findings provide evidence that polyethylene MPs likely pose a high risk of GHGs emission while combined application of Trichoderma and Bacillus subtilis significantly reduced GHGs emission by altering C and N cycling gene expression, soil microbial community structure, and enzyme activities under MPs pollution in a terrestrial ecosystem.

Bioproduction, purification, partial characterization and phenol removal efficacy of tyrosinase enzyme from Streptomyces sp. strain MR28

The study focused on the production of the tyrosinase enzyme from Streptomyces sp. MR28 and its potency in removal of phenol content from water using free and immobilized tyrosinase enzyme. The tyrosinase was produced by Streptomyces sp. MR28 in liquid tyrosine broth medium, and it was further purified to near its homogeneity by employing, precipitation, dialysis, and column chromatography. After the purification, 44.49% yield with a 4 fold purification was achieved. The characterization of the purified enzyme showed a single major peak on HPLC and a solitary band on SDS-PAGE. The purified tyrosinase enzyme was active at a pH of 7.0 and a temperature of 30 °C. Further immobilization of purified tyrosinase was performed using the sodium alginate entrapment method. The capacity of the purified tyrosinase to remove phenol in water was evaluated by spectrophotometric method. The free tyrosinase enzyme-treated solutions showed a gradual decrease in the concentration of phenol with increased incubation time at 30 °C and 40 °C, at 90 min of the incubation time, it showed maximum efficacy in removing phenol from the solution. At 50 °C and 60 °C, the free tyrosinase enzyme exhibited very less capacity to remove the phenol. The immobilized enzyme showed good capacity for the removal of phenol from the solutions; the concentration of phenol in the solution decreased with an increase in the incubation time. At temperatures of 40 °C and 50 °C, the immobilized tyrosinase enzyme beads showed significant removal of phenol from the solution, and at temperatures of 30 °C and 60 °C, they also exhibited good capacity for the removal of phenol. At the end of the 90 min incubation period, it exhibited good capability. The current study suggests using immobilized microbial tyrosinase enzyme can be used for the removal of phenol from the contaminated water in a greener manner.

Bioremediation Studies on Pesticides in Soil by Novel Microorganisms Isolated from Agricultural Fields

Pesticides are organic compounds widely used in agriculture for increasing agricultural yield, soil productivity and to control the insect vectors for prevention of various plants, human and animal epidemics. Pesticides are widely distributed in our ecosystem. Organophosphates are found to be one of the most common group of pesticides found across the world. However, excessive and indiscriminate use of pesticides have generated a number of environmental problems such as release of toxic waste in the environment resulting to contamination of air, water and terrestrial ecosystem. In order to control the harmful effects of pesticides, multiple attempts have been made like the use of physical, chemical, biological and enzymatic approaches to reduce pesticides. However, physical and chemical methods have proven to be inefficient. One of the most promising field of biotechnology that offers a novel approach to degrade the pesticides is bioremediation. Bioremediation uses microorganisms, microbial or plants enzymes to detoxify contaminants in the soil and other environments. Three group of microorganisms i.e., bacteria, actinomycetes and fungi have been found to degrade the pesticides. Bacterial group involved in degradation includes Bacillus, Pseudomonas, Flavobacterium, Arthrobacter, Paracoccus, Aerobacter, Alcaligens, and Sphingomonas. Fungi having potential bioremediation capacities includes Fusarium, Aspergilus niger, Penicillium, Oxysporum. Streptomycetes have been found to degrade pesticides among the actinomycetes group. This review highlights various aspects of microbial degradation of pesticides including the types of pesticide degrading microbes and mechanism of degradation.

Effects of the Replacement of Chemical Fertilizers with Organic Fertilizers in Different Proportions on Microbial Biomass and Enzyme Activities of Soil Aggregates in Gravel-Mulched Field

Gravel-mulched fields are a unique form of drought-resistant agriculture in the northwest region of China. In recent years, continuous cropping obstacles caused by the perennial cultivation of a single crop have seriously constrained the sustainable development of sand fields. This study aimed to explore the distribution patterns of different particle sizes of aggregates (>2, 1–2, 0.25–1, and <0.25 mm) and the relationships between their microbial biomass and enzyme activities under different organic fertilization and to explore the effective measures for improving soil fertility in a gravel-mulched field with an 8-year positioning test. The results indicate that the mass percentage of soil aggregates of ≥1 mm and their mean weight diameter (MWD), microbial biomass (carbon and nitrogen, bacteria, fungi, actinomycetes, and total phospholipid fatty acids), and their related enzyme activities (leucine aminopeptidase, LAP; N-acetyl-β-d-glucosidase, NAG; β-glucosidase, BG; and polyphenol oxidase, PPO) in aggregates of different particle sizes increased with the increase in the proportion of organic fertilizers replacing the N fertilizer. Among them, the organic fertilizer replacing more than 50% of chemical nitrogen fertilizers exerted the most significant effect. With the decrease in agglomerate particle size, the contents of microbial carbon and nitrogen showed a decreasing trend, whereas LAP, NAG, and BG activities followed an increasing trend, and the change in microbial biomass was not obvious. The correlation analysis showed highly significant positive correlations between the MWD of soil aggregates, microbial biomass, and the activities of LAP, NAG, BG, and PPO. Therefore, the replacement of more than 50% of chemical fertilizer with organic fertilizer was observed to be conducive to promoting the formation of large aggregates in sandy soils and increasing the microbial biomass and enzyme activities in different sizes of aggregates.

Effect of Vaginal Microecological Alterations on Female Pelvic Organ Prolapse.

The objective was to investigate the correlation between endogenous vaginal microecological alterations and female pelvic organ prolapse (POP). Patients who underwent vaginal hysterectomy were retrospectively analyzed as the POP group (n = 30) and the non-POP group (n = 30). The vaginal microbial metabolites and enzyme levels were tested using the dry chemoenzymatic method. The mRNA and protein expression were tested using real-time quantitative PCR and immunohistochemistry. SPSS version 25.0 and GraphPad Prism 8.0 were performed for statistical analysis. Compared with the non-POP group, the vaginal pH, H2O2 positivity and leukocyte esterase positivity were higher in patients with POP (all p < 0.05). Further analysis showed that patients with pelvic organ prolapse quantification (POP-Q) stage IV had higher rates of vaginal pH, H2O2 positivity and leukocyte esterase positivity than those with POP-Q stage III. Additionally, the mRNA expression of decorin (DCN), transforming growth factor beta 1 (TGF-β1), and matrix metalloproteinase-3 (MMP-3) in uterosacral ligament tissues were higher, whereas collagen I and III were lower. Similarly, the positive expression of MMP-3 in uterosacral ligament tissue was significantly upregulated in the POP group compared with the non-POP group (p = 0.035), whereas collagen I (p = 0.004) and collagen III (p = 0.019) in uterosacral ligament tissue were significantly downregulated in the POP group. Correlation analysis revealed that there was a significant correlation between vaginal microecology and collagen metabolism. In addition, MMP-3 correlated negatively with collagen I and collagen III (p = 0.002, r = -0.533; p = 0.002, r = -0.534 respectively), whereas collagen I correlated positively with collagen III (p = 0.001, r = 0.578). Vaginal microecological dysbiosis affects the occurrence of female POP, which could be considered a novel therapeutic option.

Caatinga, Amazon and Atlantic Forest as natural sources for microbial lignocellulolytic enzymes.

Brazilian biomes are important sources for environmental microorganisms, including efficient metabolic machineries, like actinomycetes. These bacteria are known for their abilities to produce many bioactive compounds, including enzymes with multiple industrial applications. The present work aimed to evaluate lignocellulolytic abilities of actinomycetes isolated from soil and rhizosphere samples collected at Caatinga, Atlantic and Amazon Forest. Laccase (Lac), lignin peroxidase (LiP), manganese peroxidase (MnP) and cellulase were evaluated for their efficiency. These enzymes have an essential role in lignin decomposition, through oxidation of phenolic and non-phenolic compounds, as well as enzymatic hydrolysis of vegetal biomass. In this sense, a total of 173 actinomycetes were investigated. Eleven (11) of them were selected by their enzymatic performance. The actinomycete AC166 displayed some activity in all analysed scenarios in terms of Lac, MnP and LiP activity, while AC171 was selected as the most promising strain, showing the following activities: 29.7 U.L-1 for Lac; 2.5 U.L-1 for LiP and 23 U.L-1 for MnP. Cellulolytic activities were evaluated at two pH conditions, 4.8 and 7.4, obtaining the following results: 25 U.L-1 and 71 U.L-1, respectively. Thermostability (4, 30 and 60 o C) and salinity concentrations (0 to 4M) and pH variation (2.0 to 9.0) stabilities of the obtained LiP and Lac enzymatic extracts were also verified. The actinomycete strain AC171 displayed an adaptable response in distinct pH and salt profiles, indicating that bacterial LiP was some halophilic type. Additionally, the strain AC149 produced an alkali and extreme halophilic lignin peroxidase, which are promising profiles for their future application under lignocellulosic biomass at bioethanol biorefineries.