The Viable but Non-Culturable (VBNC) State, a Poorly Explored Aspect of Beneficial Bacteria.

Many bacteria have the ability to survive in challenging environments; however, they cannot all grow on standard culture media, a phenomenon known as the viable but non-culturable (VBNC) state. Bacteria commonly enter the VBNC state under nutrient-poor environments or under stressful conditions. This review explores the concept of the VBNC state, providing insights into the beneficial bacteria known to employ this strategy. The investigation covers different chemical and physical factors that can induce the latency state, cell features, and gene expression observed in cells in the VBNC state. The review also covers the significance and applications of beneficial bacteria, methods of evaluating bacterial viability, the ability of bacteria to persist in environments associated with higher organisms, and the factors that facilitate the return to the culturable state. Knowledge about beneficial bacteria capable of entering the VBNC state remains limited; however, beneficial bacteria in this state could face adverse environmental conditions and return to a culturable state when the conditions become suitable and continue to exert their beneficial effects. Likewise, this unique feature positions them as potential candidates for healthcare applications, such as the use of probiotic bacteria to enhance human health, applications in industrial microbiology for the production of prebiotics and functional foods, and in the beer and wine industry. Moreover, their use in formulations to increase crop yields and for bacterial bioremediation offers an alternative pathway to harness their beneficial attributes.

Phytoremediation assisted by mycorrhizal fungi of a Mexican defunct lead-acid battery recycling site.

A field experiment was conducted during 15 months to study the effects of four arbuscular mycorrhizal fungi (AMF) on the growth of Ricinus communis accession SF7. Plants were established on amended soil (vermicompost:sawdust:soil 1:1:1) severely polluted by lead-acid batteries (LAB) located at Mexico State, Mexico. Plants inoculated with Acaulospora sp., Funneliformis mosseae and Gigaspora gigantea had 100% survival in comparison to non-inoculated plants (57%). These same AMF enhanced palmitic and linoleic acids content in seeds of R. communis. Acaulospora sp. modified rhizosphere soil pH and decreased 3.5 folds Pb foliar concentrations while F. mosseae BEG25 decreased three times Pb soil availability in comparison to non-inoculated plants. Spatial changes in Pb soil availability were observed at the end of this research. No fungal effect on P, Ca, Cu foliar concentrations, soluble sugars, proline, chlorophyll or on the activity of two oxidative stress enzymes was observed. Mycorrhizal colonization from the inoculated fungi was between 40% and 60%, while colonization by native fungi was between 16% and 22%. A similar percentage of foliar total phenolic compounds was observed in non-mycorrhizal plants and those inoculated with G. gigantea and Acaulospora sp. This is the first research reporting effects of AMF on R. communis (castor bean) shrubs when grown on a LAB recycling site suggesting the use of Acaulospora sp. and F. mosseae BEG25 in phytostabilization to ameliorate Pb pollution and decreasing its ecological risk.