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Background: Bacillus amyloliquefaciens is a plant growth-promoting rhizobacterium and produces several secondary metabolites with antimicrobial activity. One of its most important morphological characteristics is the presence of flagella. Currently the existing staining techniques for bacterial flagellar visualization have limitations; as increased time requirement and unstable reactions of the reagents. Objective: Therefore, the objective of this study was to describe a modification in the flagellar staining methodology, to visualize flagella in B. amyloliquefaciens bacteria by light microscopy. Methodology: Mordant was used (80 mL of 25% tannic acid solution and 15 mL of 2.5% chromium trioxide, it was mixed and left to rest for 5 days at 4 °C) and crystal violet, in bacterial colonies of 16, 18, 20, 22 and 24 h of growth. Results: After a growth period of 20-24 h, in bacterial cells of B. amyloliquefaciens, the presence of peritric flagella was observed (flagella distributed on the surface of the bacteria), which was possible through the modified flagellar staining technique developed. Implications: The correct, fast and practical visualization of bacterial flagella is important for morphological identification. Conclusion: In this research it was possible to demonstrate the visualization of bacterial flagella, with a modified technique and less manipulation of the bacteria.

Cyclic lipopeptides (LPs) are potentially promising in the agricultural, industrial and pharmaceutical sectors. LPs have a variable hydrophilic cyclic peptide part attached to a variable fatty acid chain. One limitation of these compounds is their low availability due to their limited production by bacteria. The objective of this study was to identify and quantify homologues of LPs biosynthesized by Bacillus amyloliquefaciens using ultra-performance liquid chromatography (UPLC–MS/MS) after inducing the synthesis of these secondary metabolites using different inducers, including chemical compounds and inactive cells of Colletotrichum sp. Four homologues were identified in the iturin family (bacillomycin D), and the iturin homologue with the highest synthesis was the molecular ion m/z 1031.54, with 173.1 µg mg−1 crude extract. In addition, seven homologues were detected in the fengycin family (four of fengycin A and three of fengycin B), and the homologue with the highest content was the molecular ion m/z 1463.69 (fengycin A), with 3288 ± 528.5 ng mg−1 crude extract. Finally, five homologues were identified in the surfactin family, where the highest concentration was observed for the molecular ion m/z 1036.68, with 61.5 ± 3.01 µg mg−1 crude extract. The highest concentration of LP homologues (iturin, fengycin and surfactin) synthesized by B. amyloliquefaciens was detected in the presence of inactive cells of Coletotrichum sp., suggesting that the inducing substance is associated with the inducer’s cell envelope and could be a single protein or a structure that includes protein components.