Medicinal plant-associated rhizobacteria enhance the production of pharmaceutically important bioactive compounds under abiotic stress conditions

Interest in cultivating valuable medicinal plants to collect bioactive components has risen extensively over the world to meet the demands of health care systems, pharmaceuticals, and food businesses. Farmers commonly use chemical fertilizers to attain maximal biomass and yield, which have negative effects on the growth, development, and bioactive constituents of such medicinally important plants. Because of its low cost, environmentally friendly behavior, and nondestructive impact on soil fertility, plant health, and human health, the use of beneficial rhizobial microbiota is an alternative strategy for increasing the production of useful medicinal plants under both standard and stressed conditions. Plant growth-promoting rhizobacteria (PGPR) associated with medicinal plants belong to the genera Azotobacter, Acinetobacter, Bacillus, Brevibacterium, Burkholderia, Exiguobacterium, Pseudomonas, Pantoea, Mycobacterium, Methylobacterium, and Serratia. These microbes enhance plant growth parameters by producing secondary metabolites, including enzymes and antibiotics, which help in nutrient uptake, enhance soil fertility, improve plant growth, and protect against plant pathogens. The role of PGPR in the production of biomass and their effect on the quality of bioactive compounds (phytochemicals) is described in this review. Additionally, the mitigation of environmental stresses including drought stress, saline stress, alkaline stress, and flooding stress to herbal plants is illustrated.

Taxonomic profiling and functional gene annotation of microbial communities in sediment of river Ganga at Kanpur, India: insights from whole-genome metagenomics study

The perennial river Ganga is recognized as one of India's largest rivers of India, but due to continuous anthropogenic activities, the river's ecosystem is under threat. Next-generation sequencing technology has transformed metagenomics in the exploration of microbiome and their imperative function in diverse aquatic ecosystems. In this study, we have uncovered the structure of community microbiome and their functions in sediments of river Ganga at Kanpur, India, at three polluted stretches through a high-resolution metagenomics approach using Illumina HiSeq 2500. Among the microbes, bacteria dominate more than 82% in the three polluted sediment samples of river Ganga. Pseudomonadota (alpha, beta, and gamma) is the major phylum of bacteria that dominates in three sediment samples. Genes involved in degradation of xenobiotic compounds involving nitrotoluene, benzoate, aminobenzoate, chlorocyclohexane, and chlorobenzene were significantly enriched in the microbiome of polluted stretches. Pathway analysis using KEGG database revealed a higher abundance of genes involved in energy metabolism such as oxidative phosphorylation, nitrogen, methane, sulfur, and carbon fixation pathways in the sediment metagenome data from the river Ganga. A higher abundance of pollutant degrading enzymes like 4-hydroxybenzoate 3-monooxygenase, catalase-peroxidase, and altronate hydrolase in the polluted microbiome indicates their role in degradation of plastics and dyes. Overall, our study has provided bacterial diversity and their dynamics in community structure and function from polluted river microbiome, which is expected to open up better avenues for exploration of novel functional genes/enzymes with potential application in health and bioremediation.

Genetic and Phenotypic Heterogeneity of the Nocardiopsis alba Strains of Seawater

This study deals with the genetic and phenotypic heterogeneity of the marine Nocardiopsis alba strains isolated during pre-monsoon, monsoon and post-monsoon seasons. The isolates were characterized for their morphological and biochemical attributes, growth media preferences, antibiotic susceptibility and extracellular enzyme secretion. Nocardiopsis alba strains were assessed against 12 different antibiotics, and the responses were expressed in terms of the multiple antibiotic resistance (MAR) number. The majority of the strains produced multiple extracellular enzymes: proteases, amylases and lipases. Further, the strains were characterized on the basis of 16S rRNA gene sequencing and the majority were identified as Nocardiopsis alba along with few strains of Streptomyces lopnurensis, Nocardiopsis synnemataformans and Nocardiopsis dassonvillei. Neighbor-joining (NJ) phylogenetic tree suggested variation among the genetically similar Nocardiopsis alba species. The study establishes significant heterogeneity with respect to genetic and phenotypic characteristics of the strains of Nocardiopsis alba. Phylogenetic tree and phenogram-based comparison reflect the heterogeneity in terms of different clustering patterns of the strains. Further, the whole genome sequence data available in the literature also confirm the observed heterogeneity. Nocardiopsis alba strains displayed a relatively regressive pattern of dependence on the environmental factors based on the canonical correspondence analysis plot. The study represents cultivation, characterization, phylogenetic analysis and enzymatic potential of the Nocardiopsis alba species of seawater origin.