Simultaneous Production of Multiple Antimicrobial Compounds by Bacillus velezensis ML122-2 Isolated From Assam Tea Leaf [Camellia sinensis var. assamica (J.W.Mast.) Kitam.]

Abstract

Bacillus velezensis ML122-2 is an antimicrobial-producing strain isolated from the leaf of Assam tea or Miang [Camellia sinensis var. assamica (J.W.Mast.) Kitam.]. The cell-free supernatant (CFS) of strain ML122-2 exhibits a broad-spectrum antimicrobial activity against various Gram-positive and Gram-negative bacteria as well as the mold Penicillium expansum. The genome of B. velezensis ML122-2 was sequenced and in silico analysis identified three potential bacteriocin-associated gene clusters, that is, those involved in the production of mersacidin, amylocyclicin, and LCI. Furthermore, six gene clusters exhibiting homology (75–100% DNA sequence identity) to those associated with the secondary metabolites bacilysin, bacillibactin, surfactin, macrolactin H, bacillaene, and plipastatin were identified. Individual antimicrobial activities produced by B. velezensis ML122-2 were purified and characterized by Matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry analysis, revealing three antimicrobial peptides with molecular masses corresponding to surfactin, plipastatin, and amylocyclicin. Transcriptional analysis of specific genes associated with mersacidin (mrsA), amylocyclicin (acnA), plipastatin (ppsA), and surfactin (srfAA) production by B. velezensis ML122-2 showed that the first was not transcribed under the conditions tested, while the latter three were consistent with the presence of the associated peptides as determined by mass spectrometry analysis. These findings demonstrate that B. velezensis ML122-2 has the genetic capacity to produce a wide range of antimicrobial activities that may support a specific community structure and highlight the biotechnological properties of Assam tea.

Cell-Free Supernatant from a Strain of Bacillus siamensis Isolated from the Skin Showed a Broad Spectrum of Antimicrobial Activity

“…In recent years, the discovery and characterization of small antimicrobial peptides (AMPs) produced by bacteria have aroused a lot of interest from researchers, who focus on the study of novel antimicrobial compounds as an alternative to address the worrying phenomenon of antibiotic resistance, which is rapidly becoming a global problem. Consequently, the identification of AMPs and their characterization has begun to attract increasing attention [22].…”

Production of Pumilarin and a Novel Circular Bacteriocin, Altitudin A, by Bacillus altitudinis ECC22, a Soil-Derived Bacteriocin Producer

“…The strain was taxonomically identified as B. altitudinis ECC22. Bacillus is among the major bacterial genus found in soil, and is recognized for producing valuable antibiotics and other antimicrobial compounds, including circular bacteriocins such as amylocyclicin, produced by Bacillus amyloliquefaciens [29], and pumilarin, produced by B. pumilus B4107 [26], but also other non-ribosomally synthesized peptides (NRPs) and polyketides (PKs) [11,34]. Recently, different works mining the diversity of circular bacteriocins in sequenced microbial genomes have identified Bacillus spp.…”

“…However, in recent years, the identification of new antibiotics has declined dramatically with a few scarce exceptions, such as the discovery of teixobactin and clovibactin, produced by uncultivable soil-derived bacteria [7,8]. Although the identification of new antibiotics has been significantly reduced, it is known that soil-derived bacteria, in addition to antibiotics, have the potential to produce other antimicrobial compounds [9][10][11], such as bacteriocins and other secondary metabolites, which are being assessed for their potential clinical application as viable alternatives to traditional antibiotics [12,13].…”

Complete Genome Sequence of Floricoccus penangensis ML061-4 Isolated from Assam Tea Leaf [Camellia sinensis var. assamica (J.W.Mast.) Kitam.]

“…The plate was incubated at 37°C for 24 h. A single colony of this strain was then re-streaked on TSA to obtain a pure culture 4 . ML061-4 was routinely cultivated in M17 broth (Oxoid, Basingstoke, England) supplemented with 0.5% (w/v) glucose (GM17; Sigma-Aldrich) at 30°C for 24 h 5 . Genomic DNA of F .…”

“…The plate was incubated at 37°C for 24 h. A single colony of this strain was then re-streaked on TSA to obtain a pure culture [4]. ML061-4 was routinely cultivated in M17 broth (Oxoid, Basingstoke, England) supplemented with 0.5% (w/v) glucose (GM17; Sigma-Aldrich) at 30°C for 24 h [5]. Genomic DNA of F. penangensis ML061-4 was prepared using a NucleoBond DNA extraction kit (Macherey-Nagel, Dueren, Germany), and genome sequencing was carried out using a Pacific Bioscience (PacBio) SMRT RSII sequencing platform (PacBio, Menlo Park, CA, United States).…”