Melanin-Like Pigment Synthesis by Soil Bacillus weihenstephanensis Isolates from Northeastern Poland

PLoS One. 2015 Apr 24;10(4):e0125428. doi: 10.1371/journal.pone.0125428. eCollection 2015.

Abstract

Although melanin is known for protecting living organisms from harmful physical and chemical factors, its synthesis is rarely observed among endospore-forming Bacillus cereus sensu lato. Here, for the first time, we reported that psychrotolerant Bacillus weihenstephanensis from Northeastern Poland can produce melanin-like pigment. We assessed physicochemical properties of the pigment and the mechanism of its synthesis in relation to B. weihenstephanensis genotypic and phenotypic characteristics. Electron paramagnetic resonance (EPR) spectroscopy displayed a stable free radical signal of the pigment from environmental isolates which are consistent with the commercial melanin. Fourier transform infrared spectroscopy (FT-IR) and physicochemical tests indicated the phenolic character of the pigment. Several biochemical tests showed that melanin-like pigment synthesis by B. weihenstephanensis was associated with laccase activity. The presence of the gene encoding laccase was confirmed by the next generation whole genome sequencing of one B. weihenstephanensis strain. Biochemical (API 20E and 50CHB tests) and genetic (Multi-locus Sequence Typing, 16S rRNA sequencing, and Pulsed-Field Gel Electrophoresis) characterization of the isolates revealed their close relation to the psychrotrophic B. weihenstephanensis DSMZ 11821 reference strain. The ability to synthesize melanin-like pigment by soil B. weihenstephanensis isolates and their psychrotrophic character seemed to be a local adaptation to a specific niche. Detailed genetic and biochemical analyses of melanin-positive environmental B. weihenstephanensis strains shed some light on the evolution and ecological adaptation of these bacteria. Moreover, our study raised new biotechnological possibilities for the use of water-soluble melanin-like pigment naturally produced by B. weihenstephanensis as an alternative to commercial non-soluble pigment.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacillus / genetics*
  • Bacterial Proteins / genetics
  • Chemical Phenomena
  • DNA, Bacterial / genetics
  • Melanins / biosynthesis*
  • Pigments, Biological / biosynthesis*
  • Poland
  • RNA, Ribosomal, 16S / genetics
  • Soil
  • Soil Microbiology

Substances

  • Bacterial Proteins
  • DNA, Bacterial
  • Melanins
  • Pigments, Biological
  • RNA, Ribosomal, 16S
  • Soil

Grants and funding

This work was supported by the National Science Centre of Poland (https://www.ncn.gov.pl/?language=en) grant UMO-2013/09/N/NZ8/03209 to JMD. FT-IR was performed in the Center of Synthesis and Analysis BioNanoTechno of University of Bialystok funded by the European Union as a part of the Operational Program Development of Eastern Poland 2007–2013 (project POPW.01.03.00-20-034/09-00). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.