Hrabova H, Kharchuk M, Poliakova A, Kharkhota M.

D.K. Zabolotny Institute of Microbiology and Virology of the NAS of Ukraine,

Department of antibiotics

e-mail: gau.imv@ukr.net

The search for effective producers of substances with novel properties that could be promising for use in modern biotechnology is a task of vital importance in modern science. Various pigments are widely used in agriculture and medicine. They also serve as the main components in the production of cosmetics, technical and food dyes, the creation of bioprobes and biosensors, etc. In previous studies, we have shown that the colonies of the strain Bacillus endophyticus UCM B-5715 were pigmented and fluoresced under UV-light. In respect of that, the aim of our study was to investigate the profile of pigments produced by the strain B. endophyticus UCM B-5715. Several classical and modern research methods were used in the study: the microbiological and biochemical methods, NMR- and IR-spectroscopy, gas chromatography, and high-performance liquid chromatography with mass detection. We have found that the strain B. endophyticus UCM B-5715 synthesizes a complex of pigment compounds. They were conventionally divided into three groups: resistomycin-like, melanin-like, and dark pigments. The group of resistomycin-like pigments was represented by two subgroups that differed in polarity. Some of them fluoresced in the visible spectrum under UV-light. The major pigments of this group (96% of the total), according to the obtained NMR, IR, and mass spectroscopy results, corresponded to chlorxanthomycin and heliomycin. It has been shown that the extract of these pigments inhibited the growth of several Bacillus bacteria strains and had an antitumor effect on continuous cultures of human laryngeal cancer cell lines Hep-2 and B95-8. The melanin-like pigment group was produced by the strain on the tyrosine-containing culture medium. The pigments were close to melanin in their physicochemical properties (solubility in alkalis and acids, reaction with oxidants). Their melanin nature was confirmed by IR-spectroscopy. The water solubility of these pigments was provided by a significant amount of proteins that were part of them (30-40% of the total mass). Neutral amino acids were predominant. The monosaccharide composition of melanin-like pigments was characterized by a predominance of hexoses. The dark pigment, which was synthesized on peptone-containing media, showed a negative reaction to phenolic and indole compounds as well as to the peptide bond and aromatic amino acids. Its nature remains unknown. Thus, the strain B. endophyticus UCM B-5715 synthesizes a complex of fluorescent pigments, melanin-like pigments, and dark pigments of undefined nature.