Pharmacological Properties, Volatile Organic Compounds, and Genome Sequences of Bacterial Endophytes from the Mangrove Plant Rhizophora apiculata Blume

Bioactivity and metabolic profiling of crude extracts from endophytic bacteria linked to Solanum mauritianum scope: Discovery of antibacterial and anticancer properties

Bacterial endophytes associated with Solanum mauritianum Scop. represent a promising source of novel bioactive compounds with potential antibacterial and anticancer properties. This study aimed to investigate the diversity, distribution, and bioactivity of crude extracts derived from endophytic bacteria, focusing on their effects against bacterial pathogens of public health relevance and two cancer cell lines. Fresh, healthy plant samples were collected, and endophytes were isolated using standard cultural techniques. Identification of the endophytes was carried out through conventional and molecular methods. The comprehensive profiling and characterization of crude secondary metabolites were conducted using Liquid Chromatography-Quadrupole Time-of-Flight Mass Spectrometry (LC-QTOF-MS/MS) and Gas Chromatography-High Resolution Time-of-Flight Mass Spectrometry (GC-HRTOF-MS). The antibacterial activity and minimum inhibitory concentration were evaluated for the secondary metabolites using the Resazurin Microtitre assay. The anticancer activity of the metabolites was evaluated against A549 Lung carcinoma cells and U87MG Glioblastoma cells (ATCC culture cell lines). The result revealed a diversity of bacterial endophytes, including Pantoea species, Luteibacter sp. Bacillus safensis, Arthrobacter sp., and Bacillus licheniformis. These endophytes displayed distinct-tissue-specific distribution patterns within S. mauritianum. Metabolic profiling of three endophytes (P. ananatis, B. licheniformis, and Arthrobacter sp.) revealed 14 common and numerous unique metabolites. The crude secondary metabolites exhibited broad-spectrum antibacterial activity against reference strains of Bacillus cereus, Pseudomonas aeruginosa, and Staphylococcus epidermidis, where MICs as low as 0.125 mg/ml were recorded across several secondary metabolites of Pantoea ananatis, Bacillus licheniformis, and Arthrobacter sp. The cytotoxicity assays on UMG87 glioblastoma and A549 lung carcinoma cells revealed that the secondary metabolites did not induce cell death but instead promoted cell proliferation with different viability rates. While this proliferative effect limits their direct application as anticancer agents, it raises intriguing possibilities for their role in tissue regeneration or repair. This study provides critical insights into the microbial diversity of S. mauritianum and underscores the potential of its endophytic bacteria as sources of bioactive compounds with diverse biotechnological applications.

Genomic insights into symbiosis and host adaptation of sponge-associated novel bacterium, Rossellomorea orangium sp. nov

Sponge-associated microorganisms play vital roles in marine sponge ecology. This study presents a genomic investigation of Rossellomorea sp. MCCB 382, isolated from Stelletta sp., reveals insights into its adaptations and symbiotic roles. Phylogenomic study and Overall Genomic Relatedness Index (OGRI) classify MCCB 382 as a novel species, Rossellomorea orangium sp. nov. The genome encodes numerous carbohydrate metabolism enzymes (CAZymes), likely aiding nutrient cycling in the sponge host. Unique eukaryotic-like protein domains hint at potential mechanisms of symbiosis. Defence mechanisms include CRISPR, restriction-modification systems, DNA phosphorothioation, toxin-antitoxin systems, and heavy metal and multidrug resistance genes, indicating adaptation to challenging marine environments. Unlike obligate mutualists, MCCB 382 shows no genome reduction. Furthermore, the presence of mobile genetic elements, horizontal gene transfer, and prophages suggest genetic versatility, implying flexible metabolic potential and capacity for rapid adaptation and symbiosis shifts. MCCB 382 possesses six biosynthetic gene clusters for secondary metabolites, including both type II and III polyketide synthases (PKS), terpenes, (NRPS), NRPS-independent-siderophore, and lassopeptide. Further genome mining using BiGScape revealed four distinct gene cluster families, T2PKS, NRPS-independent-siderophore, lasso peptide, and terpene, presenting opportunities for novel compound elucidation. Our study reveals a symbiotic lifestyle of MCCB 382 with the host sponge, highlighting symbiont factors that aid in establishing and sustaining this relationship. This is the pioneering genomic characterization of a novel Rossellomorea sp. within the sponge Stelletta sp. holobiont.

Biotechnological Key Genes of the Rhodococcus erythropolis MGMM8 Genome: Genes for Bioremediation, Antibiotics, Plant Protection, and Growth Stimulation

Anthropogenic pollution, including residues from the green revolution initially aimed at addressing food security and healthcare, has paradoxically exacerbated environmental challenges. The transition towards comprehensive green biotechnology and bioremediation, achieved with lower financial investment, hinges on microbial biotechnology, with the Rhodococcus genus emerging as a promising contender. The significance of fully annotating genome sequences lies in comprehending strain constituents, devising experimental protocols, and strategically deploying these strains to address pertinent issues using pivotal genes. This study revolves around Rhodococcus erythropolis MGMM8, an associate of winter wheat plants in the rhizosphere. Through the annotation of its chromosomal genome and subsequent comparison with other strains, its potential applications were explored. Using the antiSMASH server, 19 gene clusters were predicted, encompassing genes responsible for antibiotics and siderophores. Antibiotic resistance evaluation via the Comprehensive Antibiotic Resistance Database (CARD) identified five genes (vanW, vanY, RbpA, iri, and folC) that were parallel to strain CCM2595. Leveraging the NCBI Prokaryotic Genome Annotation Pipeline (PGAP) for biodegradation, heavy metal resistance, and remediation genes, the presence of chlorimuron-ethyl, formaldehyde, benzene-desulfurization degradation genes, and heavy metal-related genes (ACR3, arsC, corA, DsbA, modA, and recG) in MGMM8 was confirmed. Furthermore, quorum-quenching signal genes, critical for curbing biofilm formation and virulence elicited by quorum-sensing in pathogens, were also discerned within MGMM8's genome. In light of these predictions, the novel isolate MGMM8 warrants phenotypic assessment to gauge its potential in biocontrol and bioremediation. This evaluation extends to isolating active compounds for potential antimicrobial activities against pathogenic microorganisms. The comprehensive genome annotation process has facilitated the genetic characterization of MGMM8 and has solidified its potential as a biotechnological strain to address global anthropogenic predicaments.

Decrypting the multi-functional biological activators and inducers of defense responses against biotic stresses in plants

Plant diseases are still the main problem for the reduction in crop yield and a threat to global food security. Additionally, excessive usage of chemical inputs such as pesticides and fungicides to control plant diseases have created another serious problem for human and environmental health. In view of this, the application of plant growth-promoting rhizobacteria (PGPR) for controlling plant disease incidences has been identified as an eco-friendly approach for coping with the food security issue. In this review, we have identified different ways by which PGPRs are capable of reducing phytopathogenic infestations and enhancing crop yield. PGPR suppresses plant diseases, both directly and indirectly, mediated by microbial metabolites and signaling components. Microbial synthesized anti-pathogenic metabolites such as siderophores, antibiotics, lytic enzymes, hydrogen cyanide, and several others act directly on phytopathogens. The indirect mechanisms of reducing plant disease infestation are caused by the stimulation of plant immune responses known as initiation of systemic resistance (ISR) which is mediated by triggering plant immune responses elicited through pathogen-associated molecular patterns (PAMPs). The ISR triggered in the infected region of the plant leads to the development of systemic acquired resistance (SAR) throughout the plant making the plant resistant to a wide range of pathogens. A number of PGPRs including Pseudomonas and Bacillus genera have proven their ability to stimulate ISR. However, there are still some challenges in the large-scale application and acceptance of PGPR for pest and disease management. Further, we discuss the newly formulated PGPR inoculants possessing both plant growth-promoting activities and plant disease suppression ability for a holistic approach to sustaining plant health and enhancing crop productivity.