Inhibition of the growth of Bacillus subtilis DSM10 by a newly discovered antibacterial protein from the soil metagenome

Prospecting Microbial Genomes for Biomolecules and Their Applications

Bioactive molecules of microbial origin are finding increasing biotechnological applications. Their sources range from the terrestrial, marine, and endophytic to the human microbiome. These biomolecules have unique chemical structures and related groups, which enable them to improve the efficiency of the bioprocesses. This review focuses on the applications of biomolecules in bioremediation, agriculture, food, pharmaceutical industries, and human health.

Metagenomic Approaches as a Tool to Unravel Promising Biocatalysts from Natural Resources: Soil and Water

Natural resources are considered a promising source of microorganisms responsible for producing biocatalysts with great relevance in several industrial areas. However, a significant fraction of the environmental microorganisms remains unknown or unexploited due to the limitations associated with their cultivation in the laboratory through classical techniques. Metagenomics has emerged as an innovative and strategic approach to explore these unculturable microorganisms through the analysis of DNA extracted from environmental samples. In this review, a detailed discussion is presented on the application of metagenomics to unravel the biotechnological potential of natural resources for the discovery of promising biocatalysts. An extensive bibliographic survey was carried out between 2010 and 2021, covering diverse metagenomic studies using soil and/or water samples from different types and locations. The review comprises, for the first time, an overview of the worldwide metagenomic studies performed in soil and water and provides a complete and global vision of the enzyme diversity associated with each specific environment.

Inhibitory activity of Halobacillus trueperi S61 and its active extracts on potato dry rot

This study investigated the inhibitory activity of Halobacillus trueperi S61 and its active extract on potato dry rot pathogens and aimed at contributing to biocontrol agent development during potato storage. Three kinds of pathogens were isolated as target pathogenic fungi from dry rot tubers and determined as Fusarium acuminatum (Qing 9A-2), Fusarium equisetai (Qing 9A-5-8) and Fusarium tricinctum (Qing 9A-1-1) by morphological and molecular identification. The strain Halobacillus trueperi S61 and its extract exhibited a higher inhibitory rate on both three pathogens (56.32–65.75 and 1.67–51.11%), notably the best suppression efficiency is presented in Halobacillus trueperi S61 and 40 mg/mL ethyl acetate extract. In terms of in vivo effects, both Halobacillus trueperi S61 and its ethyl acetate extract effectively reduced the decayed fruit and weight loss rate (0–20% and 7.59–16.56%) and enhanced the defensive enzymatic activities to improve resistance. In addition, strain S61 could be colonized on potato tubers, especially the highest amount of 1.55 × 10⁷ CFU/mL on fifth day for variety Xiazhai 65. Overall, Halobacillus trueperi S61 and its ethyl acetate extract could be considered as potential approach for biocontrol potato dry rot.

Fungicides alter the distribution and diversity of bacterial and fungal communities in ginseng fields

The present study was focused on comparison of four typical fungicides in ginseng field to evaluate the impact of the different fungicides on the soil bacterial and fungal communities’ composition and diversity by using high-throughput sequencing. Five treatments were designed comprising carbendazim (D), dimethyl disulfide (E), dazomet (M), calcium cyanamide (S), and control (C). The application of fungicide obviously altered the distribution of dominant fungal and bacterial communities and remarkably decreased the diversity (1099-763 and 6457-2245). The most abundant Proteobacteria obviously degenerate in fungicide-treated soil and minimum in E (0.09%) compared to control (25.72%). The relative abundance of Acidobacteria was reduced from 27.76 (C) to 7.14% after applying fungicide and minimum in E. The phylum Actinobacteria are both decomposers of organic matter and enemies of soil-borne pathogens, elevated from 11.62 to 51.54% and are high in E. The fungi community mainly distributed into Ascomycota that enriched from 66.09 to 88.21% and highin M and E (88.21 and 85.10%), and Basidiomycota reduced from 21.13 to 3.23% and low in M and E (5.27 and 3.23%). Overall, environmentally related fungicides decreased the diversity and altered the composition of bacterial and fungal communities, highest sensitivity present in dimethyl disulfide-treated soil.

Draft Genome Sequence of the Type Strain Bacillus subtilis subsp. subtilis DSM10

The Bacillus subtilis subsp. subtilis type strain DSM10 has been used as a reference in various studies. However, detailed information about the genome has not been available. Therefore, whole-genome sequencing was performed, and the sequence was compared with that of the related B. subtilis strain NCIB3610.

The Bacillus subtilis subsp. subtilis type strain DSM10 has been used as a reference in various studies. However, detailed information about the genome has not been available. Therefore, whole-genome sequencing was performed, and the sequence was compared with that of the related B. subtilis strain NCIB3610.

Improvements in Extraction Methods of High-molecular-weight DNA from Soils by Modifying Cell Lysis Conditions and Reducing Adsorption of DNA onto Soil Particles

High-molecular-weight DNA (HMW DNA) extracted from soil is useful for examined the functions and diversity of soil organisms, the majority of which are difficult to culture. In the present study, the procedures used to extract HMW DNA from soil samples were improved. The grinding of soil samples with liquid nitrogen followed by a lysozyme treatment at 45°C for 1 h and an incubation with protease and SDS at 50°C for 5 h increased the size and yield of HMW DNA extracted from these samples. In the soil group Andosols, the addition of boiled sonicated salmon DNA was effective for HMW DNA extraction.

Biochemical Characterization of a Novel Monospecific Endo-β-1,4-Glucanase Belonging to GH Family 5 From a Rhizosphere Metagenomic Library

Cellulases have a broad range of different industrial applications, ranging from food and beverages to pulp and paper and the biofuels area. Here a metagenomics based strategy was used to identify the cellulolytic enzyme CelRH5 from the rhizosphere. CelRH5 is a novel monospecific endo-β-1,4-glucanase belonging to the glycosyl hydrolase family 5 (GH5). Structural based modeling analysis indicated that CelRH5 is related to endo-β-1,4-glucanases derived from thermophilic microorganisms such as Thermotoga maritima, Fervidobacterium nodosum, and Ruminiclostridium thermocellum sharing 30-40% amino acid sequence identity. The molecular weight of the enzyme was determined as 40.5 kDa. Biochemical analyses revealed that the enzyme displayed good activity with soluble forms of cellulose as a substrate such as ostazin brilliant red hydroxyethyl cellulose (OBR-HEC), carboxymethylcellulose (CMC), hydroxyethyl cellulose (HEC), and insoluble azurine cross-linked hydroxyethylcellulose (AZCL-HEC). The enzyme shows highest enzymatic activity at pH 6.5 with high pH tolerance, remaining stable in the pH range 4.5–8.5. Highest activity was observed at 40°C, but CelRH5 is psychrotolerant being active and stable at temperatures below 30°C. The presence of the final products of cellulose hydrolysis (glucose and cellobiose) or metal ions such as Na⁺, K⁺, Li⁺, and Mg²⁺, as well as ethylenediaminetetraacetic acid (EDTA), urea, dithiothreitol (DTT), dimethyl sulfoxide (DMSO), 2-mercaptoethanol (2-ME) or glycerol, did not have a marked effect on CelRH5 activity. However, the enzyme is quite sensitive to the presence of 10 mM ions Zn²⁺, Ni²⁺, Co²⁺, Fe³⁺ and reagents such as 1 M guanidine HCl, 0.1% sodium dodecyl sulfate (SDS) and 20% ethanol. Given that it is psychrotolerant and retains activity in the presence of final cellulose degradation products, metal ions and various reagents, which are common in many technological processes; CelRH5 may be potential suitability for a variety of different biotechnological applications.

Functional Metagenomics as a Tool for Identification of New Antibiotic Resistance Genes from Natural Environments

Antibiotic resistance has become a major concern for human and animal health, as therapeutic alternatives to treat multidrug-resistant microorganisms are rapidly dwindling. The problem is compounded by low investment in antibiotic research and lack of new effective antimicrobial drugs on the market. Exploring environmental antibiotic resistance genes (ARGs) will help us to better understand bacterial resistance mechanisms, which may be the key to identifying new drug targets. Because most environment-associated microorganisms are not yet cultivable, culture-independent techniques are essential to determine which organisms are present in a given environmental sample and allow the assessment and utilization of the genetic wealth they represent. Metagenomics represents a powerful tool to achieve these goals using sequence-based and functional-based approaches. Functional metagenomic approaches are particularly well suited to the identification new ARGs from natural environments because, unlike sequence-based approaches, they do not require previous knowledge of these genes. This review discusses functional metagenomics-based ARG research and describes new possibilities for surveying the resistome in environmental samples.