Key findings from 15 years of research: a generalist bacterium beyond endophytes.

Since the discovery of in 2010, research on (MGBs) has stagnated. Although laboratories worldwide have isolated various MGB strains and deposited their 16S rDNA sequences in the NCBI database, a limited understanding of MGBs has resulted in only a few publications from these collections. Recent advancements in metagenomic technology have revealed the presence of MGBs in a broader range of habitats. Most microbiomes exhibit low MGB abundance (typically <1%). Even in environments with higher prevalence, such as salt-tolerant aerobic granular sludge (75%), the gut of superworms fed with polyurethane (22%), or fermented foods like mandai (16%), the functional roles of MGBs remain unclear. Through meticulous curation of publications and data from MicrobeAtlas and AMIBASE, MGBs can be classified as free living, endophytic, or zoonotic. Recent evidence suggests their presence in food sources and potential interactions with humans. Current studies confirm the coexistence of MGBs with humans. This review underscores the phenotypic features and genomic foundations of MGBs, highlighting attributes such as endophytic behavior, diverse metabolite utilization, tolerance to salinity and pH, metal homeostasis, biofilm formation, and bioremediation potential. Insights are derived from the analysis of four MGB genomes deposited in NCBI since 2014, along with three newly reported genomes in 2024. Experimental and genetic evidence suggests that MGBs act as "generalist microbes" capable of thriving in diverse nutrient sources and harsh environments. This review elucidates prospective research trajectories and highlights numerous potential commercial applications of MGBs, emphasizing the need for further investigation into their roles and benefits.