In this review, a comprehensive discussion exclusively on bacterial xylanases; their gene organization; different factors and conditions affecting enzyme yield and activity; and their commercial application have been deliberated in the light of recent research findings and extensive information mining. Improved understanding of biological properties and genetics of bacterial xylanase will enable exploitation of these enzymes for many more ingenious biotechnological and industrial applications.

The use of Trichoderma isolates with efficient antagonistic activity represents a potentially effective and alternative disease management strategy to replace health hazardous chemical control. In this context, twenty isolates were obtained from tomato rhizosphere and evaluated by their antagonistic activity against four fungal pathogens (Fusarium oxysporum f. sp. lycopersici, Alternaria alternata, Colletotrichum gloeosporoides and Rhizoctonia solani). The production of extracellular cell wall degrading enzymes of tested isolates was also measured. All the isolates significantly reduced the mycelial growth of tested pathogens but the amount of growth reduction varied significantly as well. There was a positive correlation between the antagonistic capacity of Trichoderma isolates towards fungal pathogens and their lytic enzyme production. The Trichoderma isolates were initially sorted according to morphology and based on the translation elongation factor 1-α gene sequence similarity, the isolates were designated as Trichoderma harzianum, T. koningii, T. asperellum, T. virens and T. viride. PCA analysis explained 31.53, 61.95, 62.22 and 60.25% genetic variation among Trichoderma isolates based on RAPD, REP-, ERIC- and BOX element analysis, respectively. ERG-1 gene, encoding a squalene epoxidase has been used for the first time for diversity analysis of antagonistic Trichoderma from tomato rhizosphere. Phylogenetic analysis of ERG-1 gene sequences revealed close relatedness of ERG-1sequences with earlier reported sequences of Hypocrea lixii, T. arundinaceum and T. reesei. However, ERG-1 gene also showed heterogeneity among some antagonistic isolates and indicated the possibility of occurrence of squalene epoxidase driven triterpene biosynthesis as an alternative biocontrol mechanism in Trichoderma species.

Endophytic bacteria are common residents of living host tissue and occupy vital role in sustaining crop growth and health under adverse environmental situations. At present, scanty information is available about the salt-tolerant plant growth promoting (PGP) endophytic bacilli from pearl millet (Pennisetum glaucum). In the study, 102 endophytic Bacillus strains from root, leaf and stem region of pear millet host plant were isolated and limited to 28 strains depending on the salt (≥10%) tolerance ability. Phenotypic and biochemical features, together with 16S rDNA gene sequence similarity comparison with type strains identified endophytes as Bacillus albus, B. amyloliquefaciens, B. aryabhattai, B. halotolerans, B. haynesii, B. pacific, B. paramycoides, B. proteolyticus, B. pumilus, B. subtilis, B. siamensis, B. tequilensis, B. wiedmannii and B. zhangzhouensis. The rigorous in vitro screening for PGP traits, nutrient solubilization, heavy metal, polyethelene glycol, extracellular enzyme production and antagonistic potential identified B. amyloliquefaciens EPP90 as a potent multi-stress tolerant crop growth promoter. Under greenhouse experiments, plants treated with this strain reflected significantly superior plant growth relative to untreated pearl millet seed grown under saline (200 mM NaCl) environment. The research findings clearly displayed the prospective function of endophytic B. amyloliquefaciens EPP90 as an excellent multi-stress reliever and crop growth promoter.

Bipolaris species are known to be important plant pathogens that commonly cause leaf spot, root rot, and seedling blight in a wide range of hosts worldwide. In 2017, complex symptomatic cases of maydis leaf blight (caused by Bipolaris maydis) and maize leaf spot (caused by Curvularia lunata) have become increasingly significant in the main maize-growing regions of India. A total of 186 samples of maydis leaf blight and 129 maize leaf spot samples were collected, in 2017, from 20 sampling sites in the main maize-growing regions of India to explore the diversity and identity of this pathogenic causal agent. A total of 77 Bipolaris maydis isolates and 74 Curvularia lunata isolates were screened based on morphological and molecular characterization and phylogenetic analysis based on ribosomal markers—nuclear ribosomal DNA (rDNA) internal transcribed spacer (ITS) region, 28S nuclear ribosomal large subunit rRNA gene (LSU), D1/D2 domain of large-subunit (LSU) ribosomal DNA (rDNA), and protein-coding gene-glyceraldehyde-3-phosphate dehydrogenase (GAPDH). Due to a dearth of molecular data from ex-type cultures, the use of few gene regions for species resolution, and overlapping morphological features, species recognition in Bipolaris has proven difficult. The present study used the multi-gene phylogenetic approach for proper identification and diversity of geographically distributed B. maydis and C. lunata isolates in Indian settings and provides useful insight into and explanation of its quantitative findings.

Rice plants display a unique root ecosystem comprising oxic-anoxic zones, harboring a plethora of metabolic interactions mediated by its root microbiome. Since agricultural land is limited, an increase in rice production will rely on novel methods of yield enhancement. The nascent concept of tailoring plant phenotype through the intervention of synthetic microbial communities (SynComs) is inspired by the genetics and ecology of core rhizobiome. In this direction, we have studied structural and functional variations in the root microbiome of 10indicarice varieties. The studies on α and β-diversity indices of rhizospheric root microbiome with the host genotypes revealed variations in the structuring of root microbiome as well as a strong association with the host genotypes. Biomarker discovery, using machine learning, highlighted members of classAnaerolineae,α-Proteobacteria, and bacterial genera likeDesulfobacteria,Ca.Entotheonella,Algoriphagus, etc. as the most important features ofindicarice microbiota having a role in improving the plant’s fitness. Metabolically, rice rhizobiomes showed an abundance of genes related to sulfur oxidation and reduction, biofilm production, nitrogen fixation, denitrification, and phosphorus metabolism. This comparative study of rhizobiomes has outlined the taxonomic composition and functional diversification of rice rhizobiome, laying the foundation for the development of next-generation microbiome-based technologies for yield enhancement in rice and other crops.