The rapid growth of the human population has significantly increased the demand for food, leading to the intensification of agricultural practices that negatively impact the environment. Climate change poses a significant threat to global food production, as it can disrupt crop yields and modify the lifecycle stages of phytopathogens and pests. To address these challenges, the use of microbial inoculants, which are bioproducts containing beneficial microorganisms known as plant growth promotion microorganisms (PGPMs), has emerged as an innovative approach in sustainable agriculture. This review covers the isolation and identification of beneficial strains, the screening and selection process, the optimization of production techniques, and the importance of quality control and field testing. It also discusses the key points for the development and formulation of high-quality microbial inoculants, as well as highlights their advancements, current challenges, and future directions for research and application.

Nowadays, population growth, the global temperature increase, and the appearance of emerging diseases in important crops generate uncertainty regarding world food security. The use of agrochemicals has been the “go-to” solution for the control of phytopathogenic microorganisms, such as Magnaporte oryzae, causing blast disease in rice and other cereals; Botrytis cinerea, causing gray mold in over 500 plant species; and Puccinia spp., causing rust in cereals. However, their excessive use has harmed human health, as well as ecosystems (contaminating water, and contributing to soil degradation); besides, phytopathogens can develop resistance to them. The inoculation of plant growth-promoting microorganisms (PGPMs) to crops is a sustainable strategy for increasing the yield and quality of crops and mitigating biotic stresses. Likewise, PGPMs, such as Pseudomonas, Bacillus, and Trichoderma, can trigger a series of signals and reactions in the plant that lead to the induction of systemic resistance, a mechanism by which plants react to microorganism stimulation by activating their defense system, resulting in protection against future pathogen attack. These plant defense mechanisms help to mitigate biotic stresses that threaten global food security. Thus, the study of these mechanisms at molecular, transcriptomic, and metabolomic levels is indispensable to elucidate how stresses affect globally important crops.

Bacillus cabrialesii is a novel bacterial species isolated from wheat (Triticum turgidum L. subsp. durum) plants in the Yaqui Valley, Mexico, by our research team. Over years of research studying this strain at the cutting-edge level, it has shown different mechanisms of action. B. cabrialesii is strongly reported as a plant-growth-promoting bacterium and a biological control agent on wheat crops. Knowing this, B. cabrialesii has been brought from lab to field as part of a bacterial consortium, not to mention that there are ongoing investigations into formulating a cost-effective bioinoculant to increase the yield and/or quality of wheat. Moreover, studies of this novel species as a biocontrol agent in other crops (pepper, tomato, cucumber, and potato) are being carried out, with preliminary results that make B. cabrialesii a promising biological control agent, inhibiting the growth of phytopathogens. However, research into this bacterium has not only been reported in our country; there are many studies around the world in which promising native Bacillus strains end up being identified as B. cabrialesii, which reaffirms the fact that this bacterial species can promote plant growth and combat phytopathogens, showing great agrobiotechnological potential.

Jalapeño peppers (Capsicum annuum var. Jalapeño) represent one of the most important crops in Mexico. However, many plant diseases, such as wilt caused by strains of the genus Fusarium, reduce its yield. A sustainable alternative to control diseases is the use of biological control agents (BCAs), for example, beneficial microorganisms such as strains of the genus Bacillus. This study aims to analyze the potential use of B. cabrialesii subsp. tritici TSO2^T as a BCA and elucidate its potential modes of action against Fusarium strains causing wilt in Jalapeño peppers. For this, symptomatic samples were collected in a commercial field in the Yaqui Valley, Mexico. Six Fusarium isolates were morphologically and molecularly characterized. After pathogenicity tests, F. languescens CE2 was found to be pathogenic. In screening assays for biocontrol bacteria, strain TSO2^T, which was isolated from soil in a wheat commercial field under an organic production system and preserved in the Culture Collection of Native Soil and Endophytic Microorganisms (COLMENA), had the best biocontrol effect against CE2, and its cell-free filtrate reduced mycelial growth by 30.95%. Genome mining (antiSMASH) of strain TSO2^T allows us to identify gene clusters associated with biocontrol, such as fengycin, surfactin, bacillibactin, bacilysin, bacillaene, subtilosin A, and sporulation killing factor, which codify to antimicrobial metabolites and are associated with swarming motility of the studied beneficial strain. These results demonstrate the effectiveness of B. cabrialesii subsp. tritici TSO2^T as a potential BCA for the control of Fusarium wilt, through competition and a complex of antifungal metabolites, which still need to be validated through metabolomic analysis. This study highlights the importance of the use of integrative genomic and bioactivity-guided methodologies in understanding biocontrol pathosystems.

Bacillus strain PE1, which was isolated from potatoes harvested in the Yaqui Valley, Mexico, was evaluated as a potential biological control agent against Fusarium languescens. The draft genome sequence was obtained through Illumina NovaSeq sequencing, revealing a genomic size of 4,071,293 bp, with a G + C content of 44.13%, an N50 value of 357,305 bp, and 27 contigs. The taxonomic affiliation was confirmed by analyzing the 16S rRNA gene and overall genome relatedness indices (OGRIs) and constructing a phylogenomic tree based on the whole genome, which showed a close relationship to Bacillus cabrialesii subsp. cabrialesii. Genomic annotation using RAST and Prokka identified 4261 coding DNA sequences (CDSs) distributed across 331 subsystems, highlighting genes associated with biocontrol, stress response, and iron acquisition. AntiSMASH 7.1 was used for genome mining, revealing seven biosynthetic gene clusters that potentially produce biocontrol-related metabolites. In vitro assays confirmed the antagonistic activity of strain PE1 against Fusarium languescens CE2, demonstrating its potential to inhibit mycelial growth. The study provides a genomic basis for investigating B. cabrialesii subsp. cabrialesii PE1 as a potential biological control agent in potato production.

Microbes perform diverse and vital functions in animals, plants, and humans, and among them, plant-associated microbiomes, especially endophytes, have attracted growing scientific interest in recent years. Numerous plant species thriving in diverse environments have been shown to host endophytic microbes. While endophytic bacteria commonly colonize plant tissues such as stems, roots, and leaves, seed-associated endophytes generally exhibit lower diversity compared to those in other plant compartments. Nevertheless, seed-borne microbes are of particular importance, as they represent the initial microbial inoculum that influences a plant’s critical early developmental stages. The seed endophytic microbiome is of particular interest due to its potential for vertical transmission and its capacity to produce a broad array of phytohormones, enzymes, antimicrobial compounds, and other secondary metabolites. Collectively, these functions contribute to enhanced plant biomass and yield, especially under abiotic and biotic stress conditions. Despite their multifaceted roles, seed microbiomes remain underexplored in plant ecology, and their potential benefits are not yet fully understood. This review highlights recent advances in our understanding of the diversity, community composition, mechanisms of action, and agricultural significance of seed endophytic microbes. Furthermore, it synthesizes current insights into how seed endophytes promote plant health and productivity and proposes future research directions to fully harness their potential in sustainable agriculture.