The widespread use of pesticides to manage Spodoptera frugiperda has led to significant challenges. This insect has developed resistance to 47 active insecticide ingredients. Therefore, endophytic entomopathogenic bacteria have been explored as an alternative pest management strategy, offering the potential to reduce reliance on chemical pesticides. The current study aims to evaluate the colonization potential of indigenous marine Bacillus strains as endophytes in maize plants and to assess their insecticidal activity against S. frugiperda. Four inoculation methods—foliar application, seed treatment, soil drenching, and a combination of all three—were used to establish the Bacillus strains as endophytes in maize plants. Our results showed that the promising native Bacillus strains exhibited both antibacterial and insecticidal effects against S. frugiperda neonates under laboratory conditions. Foliar application of Bacillus sp. Esh39 caused the highest mortality rate (65%), followed by Bacillus tequilensis R39 (60%). However, this method did not significantly enhance plant height or chlorophyll content. The potential of these native Bacillus strains warrants further investigation to improve biological control via endophytic mediation. Our findings provide valuable insights into the bacterial diversity and functionality of mangrove ecosystems and pave the way for innovative, sustainable insect management strategies.

BackgroundMulti-drug resistant/extensively-drug resistant (MDR/XDR) Enterobacteriaceae and other Gram-negative bacteria are among the most important contemporary crises that menace mankind. Their spread into ready-to-eat (RTE) foods is a serious challenge to disease control and is associated with increased morbidity, mortality, and costs to society. It is vital to create non-antibiotic techniques to reduce/mitigate the risk of these microorganisms.ObjectiveThe current study was planned to search for the good candidate(s) biologically active lactic acid bacterial strain(s) to combat MDR/XDR Gram-negative bacteria derived from ready-to-eat foods. Materials and methodsThis study was attentive to the isolation of MDR/XDR Enterobacteriaceae and other Gram-negative bacteria in various RTE foods. Proteomic, molecular identification, and phylogenetic analysis were carried out on MDR/XDR isolates and biologically active LAB strains; antibiotic resistance profile of MDR Enterobacteriaceae and Pseudomonas were bent on. Minimum inhibitory (MIP) and bactericidal percentages (MBP) of the 4 supreme Lacticaseibacillus casei’cell-free supernatants (CFSs) were determined against selected MDR/XDR Enterobacteriaceae and Pseudomonas. The effects of catalase, pH neutralization, and heat treatment on CFSs' antibacterial activity, and their mode of action using transmission electron microscopy (TEM) were investigated.Results and conclusionMDR Enterobacteriaceae were recovered from all cheese and vegetarian salads, 20 and 33.33% of sausages and luncheon samples on violet red bile glucose agar buttressed with ampicillin, penicillin, and erythromycin, in the presence or absence of tetracycline at 20 μl ml-1. Matching to 16S rRNA sequence analysis, the MALDI-TOF MS method successfully identified 48 of 53 Enterobacteriaceae isolates to species level. More than 94% of 75 isolated strains were XDR, with MAR indices of up to 0.91; 13.33% were extended-spectrum β-lactamase producers. Of the 67 putative lactic acid bacteria isolates, 23 had inconsistent inhibitory potency; among them, only four isolates were good candidates identified as Lacticasibacillus casei, their cell-free supernatants (CFSs) were effective against all MDR/XDR Enterobacteriaceae and Pseudomonas strains with inhibition zones up to 25.00 mm; the CFSs sustained most of their antibacterial activity after treatment with catalase or heating but lost at pH 7. MIP and MBP ranged from 2 to 7% and 3 to 30%, respectively; TEM validated their bactericidal action.

Exploration of new niches for microorganisms capable of degrading recalcitrant molecules is still required. We hypothesized that the gut microbiota associated with the field S. frugiperda population carries pesticide-degrading bacteria that would enhance the host’s ability to metabolize pesticides. Three strategies were implemented to address this principle: (i) isolation and identification of chlorpyrifos-degrading gut bacteria from field-collected S. frugiperda larvae; (ii) evaluation of chlorpyrifos biodegradation capacity through in vitro assays; and (iii) assessment of the impact of specific bacterial taxa capable of degrading chlorpyrifos directly within the gut. In this study, we successfully isolated four chlorpyrifos-degrading gut bacterial isolates from a field-collected population of S. frugiperda. These isolates were identified using 16S rDNA sequencing as Klebsiella quasipneumoniae strain 60D (PP504878), Klebsiella pneumoniae strain 64D (PP504879), Klebsiella pneumoniae strain 66D (PP504880), and Klebsiella pneumoniae strain 71D (PP504881). In vitro chlorpyrifos degradation assays revealed that all isolates exhibited strong degradative capacities, with Klebsiella pneumoniae strain 64D achieving the highest degradation rate, 80.38%, after one day of inoculation. In contrast, in vivo chlorpyrifos biodegradation assessment demonstrated a clear protective effect of gut bacteria on host survival. Among the mono-associated groups, larvae colonized with Klebsiella pneumoniae strain 66D exhibited the most pronounced reduction in mortality by 19.16-fold compared to antibiotic-treated larvae following exposure to chlorpyrifos suspension.