Compared to agrochemicals, bioinoculants based on plant microbiomes are a sustainable option for increasing crop yields and soil fertility. From the Mexican maize landrace “Raza cónico” (red and blue varieties), we identified yeasts and evaluated in vitro their ability to promote plant growth. Auxin production was detected from yeast isolates and confirmed using Arabidopsis thaliana plants. Inoculation tests were performed on maize, and morphological parameters were measured. Eighty-seven yeast strains were obtained (50 from blue corn and 37 from red corn). These were associated with three families of Ascomycota (Dothideaceae, Debaryomycetaceae, and Metschnikowiaceae) and five families of Basidiomycota (Sporidiobolaceae, Filobasidiaceae, Piskurozymaceae, Tremellaceae, and Rhynchogastremataceae), and, in turn, distributed in 10 genera (Clavispora, Rhodotorula, Papiliotrema, Candida, Suhomyces, Soliccocozyma, Saitozyma Holtermaniella, Naganishia, and Aeurobasidium). We identified strains that solubilized phosphate and produced siderophores, proteases, pectinases, and cellulases but did not produce amylases. Solicoccozyma sp. RY31, C. lusitaniae Y11, R. glutinis Y23, and Naganishia sp. Y52 produced auxins from L-Trp (11.9–52 µg/mL) and root exudates (1.3–22.5 µg/mL). Furthermore, they stimulated the root development of A. thaliana. Inoculation of auxin-producing yeasts caused a 1.5-fold increase in maize plant height, fresh weight, and root length compared to uninoculated controls. Overall, maize landraces harbor plant growth-promoting yeasts and have the potential for use as agricultural biofertilizers.

Microbial metallophores are low-molecular-weight chelating agents produced by microorganisms to acquire essential metal ions. Their biosynthesis, transport, and regulation involve complex processes, specialized enzymatic machinery, and intricate regulatory networks. This review examines the multifaceted roles of metallophores in microbial ecology and their potential applications in sustainable agriculture, emphasizing their key role in trace metal acquisition, nutrient cycling, and plant–microbe interactions. Furthermore, it explores the potential applications of metallophores in agriculture, bioremediation, and biotechnology, connecting their potential to the development of novel strategies for sustainable agriculture.

The green synthesis of silver nanoparticles (AgNPs) by bacteria is a strategic route for sustainable nanobiotechnology; however, the genomic and biochemical mechanisms that make it possible remain poorly defined. In this study, bacteria native to silver-bearing mine tailings in Taxco (Mexico) were isolated, capable of tolerating up to 5 mM of AgNO₃ and producing extracellular AgNPs. Spectroscopic (430–450 nm) and structural (XRD, fcc cubic phase) characterization confirmed the formation of AgNPs with average sizes of 17–21 nm. FTIR evidence showed the participation of extracellular proteins and polysaccharides as reducing and stabilizing agents. Genomic analyses assigned the isolates as Lysinibacillus fusiformis 31HCl and L. xylanilyticus G1-3. Genome mining revealed extensive repertoires of genes involved in uptake, transport, efflux and detoxification of metals, including P-type ATPases, RND/ABC/CDF transporters, Fe/Ni/Zn uptake systems, and metal response regulators. Notably, homologues of the silP gene, which encode Ag⁺ translocator ATPases, were identified, suggesting convergent adaptation to silver-rich environments. Likewise, multiple nitroreductases (YodC, YdjA, YfKO) were detected, candidates for mediating electron transfer from NAD(P)H to Ag⁺. These findings support the role of Lysinibacillus as microbial nanofactories equipped with specialized molecular determinants for silver tolerance and AgNP assembly, providing a functional framework for microorganism-based nanobiotechnology applications.