Characterization of plant growth-promoting rhizobacterial isolates associated with food plants in South Africa.

The region around the plant root referred to as the rhizosphere, is the zone where various microbial activity occurs. It performs crucial functions such as increasing the uptake of nutrients for plant development and preventing plant against plant pathogens. Keeping in mind the beneficial role performed by rhizospheric microorganisms, rhizobacterial species were isolated from the maize and soybean plant's rhizosphere. The isolated microorganisms were evaluated for their biochemical characteristics, plant growth-promoting potentials, tolerance to different environmental conditions, and their antifungal activity against Fusarium graminearum, a fungal pathogen that infects maize. The rhizobacterial isolates with multiple plant growth-promoting potentials were identified as Bacillus spp (80.77%), Rhodocyclaceae bacterium (3.85%), Enterococcus spp (3.85%). Massilia spp (3.85%. and Pseudomonas (7.69%) species based on their 16S rRNA molecular characterization. The bacterial isolates possessed antifungal activities against Fusarium graminearum, promote maize and soybeans seed under laboratory conditions, and exhibited different levels of tolerance to pH, temperature, salt, and heavy metal. Based on this, the whole genome sequencing of Bacillus sp. OA1, Pseudomonas rhizosphaerea OA2, and Pseudomonas sp. OA3 was performed using Miseq Illumina system to determine the functional genes and secondary metabolites responsible for their plant growth-promoting potential Thus, the result of this research revealed that the selected bacterial isolates possess plant growth-promoting potentials that can make them a potential candidate to be employed as microbial inoculants for protecting plants against phytopathogens, environmental stress and increasing plant growth and productivity.

Propagation and characterization of viable arbuscular mycorrhizal fungal spores within maize plant (Zea mays L.).

BACKGROUND: The harmful effect of chemical fertilizer application on human health and the environment as a modern method of meeting the food demand of the increasing world population demands an urgent alternative that is environmentally friendly, which will pose no harm to human health and the environment. Arbuscular mycorrhizal fungi (AMF) are beneficial soil microorganisms that provide various ecological functions in increasing soil fertility and enhancing plant growth. This present study aimed to propagate, characterize and examine the effect of viable arbuscular mycorrhizal fungal spores on maize (Zea mays L) hosts using molecular methods. The propagation of AMF in the host plant using sterile soil and vermiculite was conducted in the greenhouse. RESULT: The effect of AMF inoculation revealed a significant difference (P > 0.05) in maize growth, root colonization and AMF spore count when compared with the control. In all the parameters measured in this study, all the AMF spores propagated had a positive effect on the maize plant over the control, with the highest value mostly recorded in Rhizophagus irregularis AOB1. The molecular characterization of the spore using a specific universal primer for Glomeromycota established the success of the propagation process, which enhanced the classification of the AMF species into Rhizophagus irregularis OAB1, Glomus mosseae OAB2 and Paraglomus occultum OAB3. CONCLUSION: This finding will be a starting point in producing arbuscular mycorrhizal inoculum as a biofertilizer to enhance plant growth promotion. © 2021 Society of Chemical Industry.

Microbial Diversity of Temperate Pine and Native Forest Soils Profiled by 16S rRNA Gene Amplicon Sequencing.

Most biodiversity measures indicate an ongoing deterioration due to intensifying anthropogenic pressures even though efforts are being intensified worldwide to conserve biodiversity. Knowledge of the implication of land use change on soil bacterial communities is essential for ecosystem restoration. Here, the effect of the conversion of native forests to temperate pine forests on soil bacterial diversity and community composition was investigated. The diversity and composition of the bacterial communities were affected by land use change across the sites.

Draft Genomic Analysis of Pseudomonas sp. Strain OA3, a Potential Plant Growth-Promoting Rhizospheric Bacterium.

The genome analysis of the plant growth-promoting rhizospheric Pseudomonas sp. strain OA3, isolated from maize in North West Province, South Africa, is reported in this study. Pseudomonas sp. strain OA3 exhibits plant growth-promoting ability by enhancing maize and soybean growth.

Plant Disease Management: Leveraging on the Plant-Microbe-Soil Interface in the Biorational Use of Organic Amendments.

Agriculture is faced with many challenges including loss of biodiversity, chemical contamination of soils, and plant pests and diseases, all of which can directly compromise plant productivity and health. In addition, inadequate agricultural practices which characterize conventional farming play a contributory role in the disruption of the plant-microbe and soil-plant interactions. This review discusses the role of organic amendments in the restoration of soil health and plant disease management. While the use of organic amendments in agriculture is not new, there is a lack of knowledge regarding its safe and proper deployment. Hence, a biorational approach of organic amendment use to achieve sustainable agricultural practices entails the deployment of botanicals, microbial pesticides, and organic minerals as organic amendments for attaining plant fitness and disease suppression. Here, the focus is on the rhizosphere microbial communities. The role of organic amendments in stimulating beneficial microbe quorum formation related to the host-plant-pathogen interactions, and its role in facilitating induced systemic resistance and systemic-acquired resistance against diseases was evaluated. Organic amendments serve as soil conditioners, and their mechanism of action needs to be further elaborated to ensure food safety.

High-throughput sequencing data of soil bacterial communities from Tweefontein indigenous and commercial forests, South Africa.

In this report, the high-throughput sequencing data of soil bacterial communities from indigenous and commercial forests in Tweefontein, South Africa are presented. These data were collected to study the influence of land-use change on soil bacterial diversity and community structure in forests. Illumina Miseq sequencing of 16S rRNA gene amplicon was carried out on soils sampled from Tweefontein commercial (TC) and indigenous (TI) forests in South Africa. The metagenome contained 101,938 sequences with 46,709,377 bp size and 57% G + C content in TI and 91,160 sequences with 41,707,827 bp size and 57% G + C content in TC. Metagenome sequence information are available at NCBI under the Sequence Read Archive (SRA) database with accession numbers SRR8134476 (TI) and SRR8135323 (TC). Taxonomic hits distribution from Metagenomic Rast Server (MG-RAST) analysis of the TI sample revealed the dominance of the phyla Acidobacteria (21.61%), Actinobacteria (18.23%) and Verrucomicrobia (16.78%). Predominant genera were Candidatus Koribacter (12.82%), Candidatus Solibacter (11.74%) and Chthoniobacter (9.36%). MG-RAST assisted analysis of TC sample also detected the dominance of Actinobacteria (23.62%) along with Verrucomicrobia (21.92%) and Acidobacteria (20.74%). Predominant genera were Chthoniobacter (24.94%), Candidatus Solibacter (16.74%) and Candidatus Koribacter (9.39%) which play vital ecological functions in forest ecosystems.

Deciphering the microbiota data from termite mound soil in South Africa using shotgun metagenomics.

We present the metagenomic dataset of the microbial DNA of a termite mound in the North West Province of South Africa. This is the foremost account revealing the microbial diversity of a termite mound soil using the shotgun metagenomics approach in the Province. Next-generation sequencing of the community DNA was carried out on an Illumina Miseq platform. The metagenome comprised of 7,270,818 sequences representing 1,172,099,467 bps with a mean length of 161 bps and 52% G + C content. The sequence data is accessible at the NCBI SRA under the bioproject number PRJNA526912. Metagenomic Rapid Annotations using Subsystems Technology (MG-RAST) was employed for community analysis and it was observed that 0.36% sequences were of archeal origin, 9.51% were eukaryotes and 90.01% were fit to bacteria. A total of 5 archeal, 27 bacterial, and 22 eukaryotic phyla were revealed. Abundant genera were Sphingomonas (6.00%), Streptomyces (5.00%), Sphingobium (4.00%), Sphingopyxis (3.00%), and Mycobacterium (3.00%), representing 19.23% in the metagenome. For functional examination, Cluster-of-Orthologous-Group (COG) based annotation showed that 46.44% sequences were metabolism associated and 17.45% grouped in the poorly characterized category. Subsystem based annotation method indicated that 14.00% sequences were carbohydrates, 13.00% were clustering-based subsystems, and 10.00% genes for amino acids and derivatives together with the presence of useful traits needed in the body of science.

Termite Societies Promote the Taxonomic and Functional Diversity of Archaeal Communities in Mound Soils.

Recent studies involving microbial communities in termite mounds have been more focused on bacteria and fungi with little attention given to archaea, which play significant roles in nutrient cycling. Thus, we aimed at characterizing the archaeal taxonomic and functional diversity in two termite mound soils using the shotgun sequencing method with the assumption that termite activities could promote archaeal diversity. Our findings showed that termite mound soils have archaeal groups that are taxonomically different from their surrounding soils, with Euryarchaeota, Korarchaeota, and Nanoarchaeota being predominant while Thaumarchaeota and Crenarchaeota were predominant in the surrounding soils. Additionally, the observed nutrient pathways: phosphorus, nitrogen, and sulfur were all significantly more predominant in termite mound soils than in their comparative surrounding soils. Alpha diversity showed that archaea were not significantly different within termite mound soils and the surrounding soils. The beta diversity revealed significant differences in the archaeal taxonomic composition and their functional categories between the termite mounds and surrounding soils. Our canonical correspondence analysis revealed that the distribution of archaeal communities was likely dependent on the soil properties. Our results suggested that termite activities may promote the diversity of archaea; with some of our sequences grouped as unclassified archaea, there is a need for further research to unveil their identity.