Computational Molecular Biology 2026, Vol.16, No.3, 194-204 http://bioscipublisher.com/index.php/cmb 200 6 Molecular and Analytical Approaches in Rhizosphere Microbial Research 6.1 High-throughput sequencing technologies Metagenomics and marker-gene amplicon sequencing are the core high-throughput tools for rhizosphere studies, enabling cultivation-independent profiling of complex communities. Review work highlights shotgun metagenomics for unbiased recovery of genomes and functional genes, and 16S rRNA or ITS amplicon sequencing for efficient taxonomic surveys of bacteria and fungi in root-associated soils (Rajguru et al., 2024). In legume rhizospheres, such approaches reveal dominant phyla and shifts in community structure under contrasting fertilization regimes, for example in soybean grown with organic versus inorganic inputs (Babalola et al., 2025). Recent methodological advances focus on scalability and sensitivity for plant-associated samples. A high-throughput 16S rRNA library-preparation protocol using magnetic beads for DNA extraction directly from roots and exonuclease purification before the second PCR step improves handling and detection of minor bacterial taxa, yet produces community profiles comparable to commercial kits in roots and soils (Kumaishi et al., 2022). Standardized field-to-sequencing protocols have also been developed for collecting soil, rhizosphere, and root endosphere fractions and running validated 16S pipelines, facilitating cross-study comparisons across plant species and habitats. 6.2 Bioinformatics and data analysis Downstream of sequencing, dedicated bioinformatics pipelines convert read data into diversity metrics, taxonomic profiles, and functional inferences. A practical guide summarizes recommended workflows for amplicon and metagenomic analyses, detailing quality control, denoising or clustering, taxonomic assignment, diversity estimation, and advanced methods such as network analysis and machine learning to extract ecological meaning from microbiome datasets (Liu et al., 2020). Habitat-specific optimization is increasingly emphasized: evaluation of 35,889 microbe species and >150,000 microbiomes produced Qscore, a framework to select optimal 16S regions and strategies for different ecosystems, achieving profiling precision close to shotgun metagenomes (Zhang et al., 2023). Pipeline choice can strongly bias apparent community structure and diversity. Comparative assessments of 16S amplicon workflows using mock communities and environmental datasets show large differences among tools such as Mothur, QIIME1, QIIME2, MEGAN, DADA2, and others; in one study, QIIME2 markedly reduced false positives and improved taxonomic and diversity estimates relative to alternatives (Straub et al., 2020). Another comparison of OTU- and ASV-based pipelines found that ASV methods such as DADA2 and USEARCH-UNOISE3 improved resolution and specificity, while some OTU workflows inflated richness and spurious taxa, underscoring the need for careful pipeline selection in rhizosphere research (Prodan et al., 2020). 6.3 Experimental models and cultivation techniques Sequencing-based surveys are increasingly complemented by experimental models that allow mechanistic tests of plant-microbe interactions. Synthetic microbial communities (SynComs) constructed from cultured rhizosphere isolates have been systematically reviewed as tools to bridge complexity and control; SynComs ranging from a few to ~190 strains, typically dominated by Proteobacteria, Actinobacteria, and Firmicutes, are deployed on diverse plant hosts and growth systems to dissect functions such as colonization, competition, and plant growth promotion (Marín et al., 2021). A 16-member synthetic soil community derived from a single rhizosphere was further optimized for reproducibility, tunable starting composition, long-term cryopreservation, and use in standardized fabricated ecosystem devices (EcoFABs), enabling controlled plant-microbe experiments across laboratories (Coker et al., 2022). Cultivation remains crucial for isolating functional strains and validating metagenomic predictions, but many rhizosphere microbes are recalcitrant to standard media. Improved culture-dependent strategies-such as modifying gelling agents and autoclaving steps-enhanced recovery of wheat rhizosphere bacteria from <1% to up to ~2.5% of metagenomic OTUs and yielded isolates with multiple plant growth-promoting traits (Youseif et al., 2021). Microcosm and multitrophic systems, supported by detailed manuals on soil sterilization, isolation, inoculation, and microcosm design, further allow controlled investigation of bacteria, fungi, protists, and nematodes together, better reflecting the complexity of rhizosphere food webs.
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