Microbiology and Biotechnology Research: An Overview Vol. 10

Rhizobacteria in Plant Growth Promotion: Mechanistic Foundations, Ecological Contingencies and Translational Constraints

2026-09-17T11:05:13+00:00

Rhizobacteria are central participants in the biological regulation of plant nutrition, development, stress tolerance and defence. Their capacity to fix or conserve nitrogen, mobilise phosphorus and micronutrients, alter phytohormone balance, lower stress ethylene, release volatile signals and suppress pathogens has made plant growth-promoting rhizobacteria prominent candidates for reducing dependence on mineral fertilisers and pesticides. Yet the literature is marked by a persistent disparity between mechanistic promise under controlled conditions and variable performance in field soils. This critical narrative review evaluates rhizobacteria as components of plant growth promotion by integrating evidence on rhizosphere assembly, colonisation, direct and indirect mechanisms, abiotic-stress mitigation, inoculant formulation, field efficacy, microbiome interactions and biosafety. Literature available from 1978 to 31 May 2026 was selected through transparent searches of accessible scholarly indexes and bibliographic registries, with emphasis on verified peer-reviewed evidence and claim-level appraisal. The strongest conclusions concern the mechanistic plausibility of nutrient mobilisation, 1-aminocyclopropane-1-carboxylate deaminase activity, auxin-mediated root remodelling and induced systemic resistance. Confidence is lower when these traits are used alone to predict agronomic benefit, because expression depends on plant genotype, soil chemistry, resident microbiota, climate, formulation and management. Meta-analytical evidence indicates overall positive effects of microbial inoculation, but also shows inflation under sterile, short-duration and pot-based experiments. Reliable translation therefore requires a shift from trait-positive strain selection towards context-matched ecological design, verified root competence, durable formulations, multi-environment trials and monitoring of persistence and non-target effects. Rhizobacteria should not be regarded as universal substitutes for conventional inputs. Their defensible role is as biologically active, management-dependent components of integrated nutrient, stress and disease management systems.

Convergence of Artificial Intelligence and Biotechnology for Climate-Resilient Crop Improvement: Genomics, Phenomics, Gene Editing and Predictive Breeding

2026-09-17T11:10:36+00:00

Climate change is increasing the frequency, intensity and co-occurrence of heat, drought, flooding, salinity and biotic pressures that destabilise crop performance, while conventional breeding cycles remain slow relative to the pace of environmental change. At the same time, crop improvement has entered a data-rich and intervention-rich era in which genomics, pan-genomics, multi-omics, high-throughput phenotyping, genome editing and predictive breeding can be connected by artificial intelligence (AI). This critical narrative review evaluates whether that convergence is producing a coherent route from climate signal to deployable cultivar rather than a collection of parallel technologies. Literature was selected through structured searches of multidisciplinary, agricultural and biomedical scholarly sources, complemented by citation tracing and bibliographic verification. The synthesis indicates that AI contributes most reliably when it addresses a defined breeding decision: extracting field phenotypes, prioritising candidate genes, modelling genotype-by-environment responses, predicting breeding values, or optimising editing designs. Evidence is less convincing for claims that complex deep-learning architectures consistently outperform well-tuned statistical models, or that AI-nominated targets routinely translate into durable, multi-environment field resilience. Genomics and pan-genomics expand the searchable allelic space, phenomics and envirotyping improve measurement of context-dependent traits, genome editing provides a causal perturbation layer, and genomic prediction converts heterogeneous evidence into selection decisions. Their strongest integration therefore resembles a closed learning cycle of observation, inference, perturbation, field validation and model updating. Major constraints include biased training populations, reference-genome and phenotype bias, environmental domain shift, limited causal identification, transformation bottlenecks, pleiotropy, insufficient multi-location validation, weak uncertainty propagation, data interoperability and unequal access to digital and molecular infrastructure. Future progress should prioritise prospective breeding-scale evaluations in which integrated AI-biotechnology pipelines are judged by genetic gain, stability across target populations of environments, cycle time, cost and deployability. The convergence is scientifically credible, but its transformative value will depend less on algorithmic novelty than on rigorous biological validation and decision-centred integration across the breeding pipeline.

Engineering the Plant–Soil Microbiome for Climate-Resilient and Low-Emission Agriculture

2026-09-17T11:25:11+00:00

Agricultural microbiome research has progressed from descriptive inventories of root- and soil-associated taxa towards deliberate manipulation of microbial functions. This transition is strategically important because climate-resilient production and greenhouse-gas mitigation are often treated as separate objectives even though both depend on coupled plant, microbial and biogeochemical processes in the rhizosphere. This critical narrative review evaluates how plant-soil microbiomes can be engineered to improve crop performance under climatic stress while reducing emission-intensive nitrogen and carbon losses. Literature published from 1 January 2000 to 4 July 2026 was prioritised, with earlier evidence considered only when mechanistically indispensable. Evidence was appraised according to experimental control, ecological realism, causal manipulation, persistence, directness of agronomic and gas-flux outcomes, and transferability across soils and genotypes. The strongest causal evidence for microbiome function comes from reductionist synthetic-community and root-exudate studies, whereas the strongest field-relevant evidence is concentrated in host-genotype effects, biological nitrification inhibition, selected nitrous-oxide-reducing rhizobia, and long-term management effects on resident microbiomes. Drought and salinity studies support a role for beneficial bacteria and arbuscular mycorrhizal fungi, but treatment responses remain heterogeneous and mechanistic gene-expression claims are less consistent than broad plant-performance responses. For low-emission agriculture, biological nitrification inhibition and microbial nitrous oxide sinks have unusually clear process targets, although their performance is strongly soil- and crop-dependent. Microbial carbon-use efficiency, necromass formation and methane cycling provide plausible additional targets, but direct field evidence that microbiome engineering produces durable soil-carbon gains or reliably suppresses rice methane remains comparatively limited. Translation therefore requires a shift from taxonomic signatures to function-first design, multi-environment validation, direct greenhouse-gas measurements, persistence testing, and simultaneous assessment of yield stability and environmental trade-offs.

RNA Interference and Peptide-Based Biopesticides for Sustainable Crop Protection: A Critical Appraisal of Mechanism, Delivery and Translational Readiness

2026-09-17T11:29:29+00:00

Crop protection is under simultaneous pressure from persistent yield losses to arthropods and pathogens, the attrition of conventional active ingredients through resistance and regulatory withdrawal, and rising expectations that pest management should be selective and environmentally defensible. Two biologically programmable modalities have moved furthest towards meeting those expectations: exogenously applied or plant-expressed double-stranded ribonucleic acid, which silences pest or pathogen genes through the RNA interference pathway, and peptide-based agents, which include insecticidal venom-derived peptides, antimicrobial and defence-eliciting peptides, and engineered peptide carriers. This review critically evaluates the two modalities together rather than separately, on the argument that they now share the same translational bottlenecks and are increasingly deployed as a single formulation. The literature was assembled through structured searching of open bibliographic and scholarly indexes to a defined final search date, with every retained source verified against publisher metadata. The synthesis indicates that the strongest evidence for either modality remains concentrated in a small number of pest systems, principally coleopteran defoliators and root feeders for RNA interference and a small number of venom-derived and antimicrobial peptide systems for the peptide modality, and that extrapolation beyond those systems is not well supported. Efficacy variation across taxa is now attributable to identifiable and partly tractable barriers, including extracellular nucleases, endosomal entrapment and tissue-dependent uptake, rather than to unexplained species idiosyncrasy. Resistance has been selected under laboratory conditions for double-stranded RNA and has emerged in the field for related protein-based actives, which weakens the assumption that sequence-programmable actives are intrinsically durable. Environmental fate data indicate rapid dissipation of applied nucleic acid in soil, while non-target evidence remains dominated by short-term, single-species assays. The principal unresolved questions concern field-scale dose–response relationships, the durability of both modalities under realistic selection, and the cost structures that determine whether either becomes accessible outside high-value cropping. Confidence in current conclusions is constrained by the concentration of evidence in a few laboratories, crops and regions.

Microbiological and Physicochemical Assessment of Selected Drinking Water Sources in Diobu, Port Harcourt, Nigeria

2026-09-17T11:31:57+00:00

Diseases caused by drinking contaminated water pose a serious risk to public health. In Nigeria, particularly in the Diobu district of Port Harcourt, Rivers State, the majority of residents rely on boreholes, wells, and other water sources for their daily consumption, often without considering the microbial or chemical quality of these sources. This study was conducted to determine the microbiological and physicochemical characteristics of drinking water sources in Diobu, Port Harcourt, Nigeria. Ten borehole sites and ten popular brands of sachet water sold in Nigeria under the name "pure water" were sampled in Diobu, Port Harcourt. Physicochemical and bacteriological investigations were conducted using standard analytical techniques. The physicochemical analysis showed that sachet water had higher pH values than borehole water, with borehole samples exhibiting a mean pH of 4.37 ± 1.21, below the WHO-recommended range of 6.5–8.5. Total Suspended Solids (TSS) were within permissible limits (30 mg/L), with borehole water having the highest mean (6.5 ± 4.31 mg/L) and sachet water the lowest (2.5 ± 1.5 mg/L). Total Dissolved Solids (TDS) ranged from 15.8 ± 13.5 mg/L in sachet water to 55.6 ± 33.4 mg/L in borehole water. Electrical Conductivity was 33.5 ± 28.4 µS/cm in sachet water and 136.6 ± 73.9 µS/cm in borehole water. Total alkalinity ranged from 0.57 ± 0.29 mg/L (sachet) to 3.29 ± 1.39 mg/L (borehole), while water hardness ranged from 1.95 ± 0.84 mg/L to 10.67 ± 3.21 mg/L, respectively. Biological Oxygen Demand (BOD) was <1 ± 0.00 mg/L in sachet water and 2.13 ± 1.38 mg/L in borehole water. Dissolved Oxygen (DO) levels ranged from 1.72 ± 0.70 mg/L (sachet) to 1.95 ± 0.62 mg/L (borehole), and Chemical Oxygen Demand (COD) ranged from 2.38 ± 1.18 mg/L (sachet) to 11.31 ± 9.49 mg/L (borehole). Turbidity varied from <1 ± 0.00 NTU (sachet) to 1.1 ± 0.64 NTU (borehole). Only COD showed a statistically significant difference (P < 0.05). Microbiological analysis revealed high contamination in borehole water, with a mean total bacterial count of 9.0 × 10^4 CFU/mL, compared with 2.0 × 10^4 CFU/mL in sachet water, which also had the lowest coliform levels among the sources tested. Compared with the other sources, sachet water had the lowest overall bacterial and coliform levels. However, because the total coliform counts were above the WHO threshold of zero per 100 ml, the samples did not comply with international standards. Pathogenic bacteria of public health significance, including Salmonella spp., Pseudomonas spp., Staphylococcus spp., and Escherichia coli, were isolated from the water samples. Five fungal isolates (Penicillium spp., Aspergillus niger, Aspergillus flavus, Trichoderma spp., and Mucor spp.) were also detected.

Borehole water exhibited the highest bacterial contamination, while sachet water had the lowest. These findings suggest that all water sources should be properly treated before domestic use because they are currently unsuitable for human consumption.