Bacillus sp. G2112, an isolate from cucumber plants that inhibited plant pathogens, produces not only surfactins, iturins, and fengycins common to many
Bacillus spp., but also a large variety of
N-acyl-(depsi)peptides related to A-3302-B and nobilamides. Four known and fourteen previously unreported
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Bacillus sp. G2112, an isolate from cucumber plants that inhibited plant pathogens, produces not only surfactins, iturins, and fengycins common to many
Bacillus spp., but also a large variety of
N-acyl-(depsi)peptides related to A-3302-B and nobilamides. Four known and fourteen previously unreported nobilamide peptides were characterized using high-resolution mass spectrometry, tandem mass spectrometry, and NMR. The stereochemistry of the amino acids of nobilamide peptides was determined using Marfey’s method. The diversity of nobilamide peptides from
Bacillus sp. G2112 resulted from the incorporation of different acyl groups and amino acids in the sequence. The peptides occur in linear or cyclic form. In addition, a truncated
N-acetylpentapeptide was produced. Agar diffusion assays with selected nobilamide peptides against plant pathogens and human pathogens revealed that A-3302-B and its
N-acyl homologs, A-3302-A and nobilamide J, exhibited powerful antibiotic activity (at 5 µg/hole) against
Lysinibacillus sphaericus that can cause severe sepsis and bacteremia in patients. Moreover, nobilamide peptides from
Bacillus sp. G2112 strongly promoted biofilm formation in the Gram-positive
Mycobacterium aurum and Gram-negative pseudomonads. Structurally diverse nobilamides from
Bacillus sp. G2112, whether linear or cyclic, penta and heptapeptides, induced biofilm formation, suggesting that the common
N-acetyl-D-Phe-D-Leu-L-Phe-D-allo-Thr-L-Val amino acid sequence motif is important for the biofilm-inducing activity.
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