Rock phosphate (RP) is a natural source of phosphorus for agriculture, with the advantage of lower cost and less impact on the environment when compared to synthetic fertilizers. However, the release of phosphorus (P) from RP occurs slowly, which may limit its short-term availability to crops. Hence, the use of P-solubilizing microorganisms to improve the availability of P from this P source is an interesting approach, as microorganisms often perform other functions that assist plant growth, besides solubilizing P. Here, we describe the characterization of 101 bacterial isolates obtained from the rhizosphere and endosphere of maize plants for their P solubilizing activity in vitro, their growth-promoting activity on millet plants cultivated in soil amended with RP, and their gene content especially associated with phosphate solubilization. For the in vitro solubilization assays, two mineral P sources were used: rock phosphate from Araxá (Brazil) mine (AP) and iron phosphate (Fe-P). The amounts of P released from Fe–P in the solubilization assays were lower than those released from AP, and the endophytic bacteria outperformed the rhizospheric ones in the solubilization of both P sources. Six selected strains were evaluated for their ability to promote the growth of millet in soil fertilized with a commercial rock phosphate (cRP). Two of them, namely Bacillus megaterium UFMG50 and Ochrobactrum pseudogrignonense CNPMS2088, performed better than the others in the cRP assays, improving at least six physiological traits of millet or P content in the soil. Genomic analysis of these bacteria revealed the presence of genes related to P uptake and metabolism, and to organic acid synthesis. Using this approach, we identified six potential candidates as bioinoculants, which are promising for use under field conditions, as they have both the genetic potential and the experimentally demonstrated in vivo ability to improve rock phosphate solubilization and promote plant growth.

The investigation and development of novel antimicrobial compounds are central focuses of medical research. In this study, we evaluated benzimidazoles and benzothiazoles derivatives, and biosurfactants produced by Lactobacillus jensenii P_6A and Lactobacillus gasseri P₆₅ as potential antimicrobial agents against the Candida tropicalis, C. albicans, and C. krusei, Enterobacter aerogenes, Escherichia coli, Klebsiella pneumoniae, and Staphylococcus saprophyticus. Several biomolecules exhibited antimicrobial activity against clinical isolates of E. coli and C. albicans, with MIC values of 16 µg mL^-1, and against S. saprophyticus, E. aerogenes, and K. pneumoniae, with MICs less than 128 µg mL^-1. Six azole compounds exhibited antimicrobial activity against C. albicans and E. coli, with MIC values ranging from 64 to 128 µg mL^-1, and five showed activity against Candida spp. and A. niger. Both biomolecules also exhibited an antiadhesive effect at varying concentrations, being most efficient against E. aerogenes (64% for the P_6A biosurfactant), E. coli (46.4% for the P₆₅ biosurfactant), and S. saprophyticus (39% for the P₆₅ biosurfactant). Azole compounds I06, I16, I17, T04, and T17 were evaluated for their combined antimicrobial effects with biosurfactants against E. coli and C. albicans. In general, these compounds showed a synergistic effect in vitro. Additionally, in vitro cytotoxicity against two cell lines, HL6 tumor cells and normal VERO cells, was assessed. The benzimidazole derivatives I06 and I17 exhibited cytotoxic activity against HL6 tumor cells, with 50% inhibition of cell viability at 6.25 µg mL^-1 and 12.5 µg mL^-1, respectively. Furthermore, compound I06 was active in all tested cell lines, showing less than 20% inhibition of cell proliferation in VERO cells, suggesting low toxicity. The biosurfactants did not inhibit the growth of either tumor or normal cells. In this context, the development of benzazole derivatives represents a promising alternative for the design of effective antimicrobial agents. The synergistic and cytotoxic effects of the tested compounds were assessed in vitro, with preliminary safety conclusions drawn solely from Vero cell data.