Утворення пігментів фотолітотрофними сіркобактеріями Lamprocystis sp. Ya-2003 за впливу солей важких металів

Abstract

Photolithotrophic sulfur bacteria at presence in medium H2S as electron donor and СО2 as electron acceptor at anaerobic conditions carry out anoxygenic photosynthesis using light as energy source. Main photosynthetic active pigments of purple sulfur bacteria are bacteriochlorophylls and carotenoids. Biosphere pollution by heavy metals negatively influence on living components of biocenoses. Synthesis of pigments by purple sulfur bacteria and their spectral characteristics under the influence of heavy metals are studied insufficiently. The aim of work was to investigate the influence of some bivalent metals (nickel, cobalt, iron and zinc) ions on pigments synthesis by purple sulfur bacteria cells of Lamprocystis genus, isolated from enriched by hydrogen sulfide water of Yavoriv Lake. Bacteria Lamprocystis sp. Ya-2003 was cultivated under anaerobic conditions on lighting in van Niel medium for 10 days. To study the influence of heavy metals ions on quality and quantity composition of photosynthetic pigments the cells were sediment by centrifugation (centrifuge ОS-6M) at 4025 g during 30 min and incubated during 1 h with metals salts: NiCl2, CoCl2, FeCl2 × 4 H2O, ZnCl2 × 7 H2O, at concentrations: 0; 0.5; 1; 1.5; 2; 2.5; 3; 4 mM. Biomass was determined by turbidymetric method, absorption spectra and pigments content in purple sulfur bacteria cells – by spectrophotometric method. To obtaining pigment extracts the cells were dried at temperature 40 °С and destructed by rubbing with quarts sand. Pigments extraction carried out by mixture ethanol and acetone (1:1 v/v) to complete colorlessing of sediment. Obtaining extracts were using to registration of absorption spectra. Separation of pigments mixture was carried out by chromatography on silufol plates (“Sorbfil”, Russia) in the upflow of the system of solvents petrol : acetone : petroleum ether : hexane (10:10:3:10 v/v). Carotenoids were eluted from silikagel by an acetone or petroleum ether, bacteriochlorophyll – by an ethanol. Pigments identification carried out on coloring, by the sizes of Rf and basic maximums of absorption at a corresponding wave-length. Absorption spectra of extracted pigments of phototrophic sulfur bacteria were determined in the range of lengths of waves from 350 to 800 нм with the use of spectrophotometer SP-46. It was established that photosynthetic purple sulfur bacteria Lamprocystis sp. Ya-2003 contain carotenoids of spirilloxanthin row, in particular, spirilloxanthin, likopin and rhodopin, and also bacteriochlorophyll a. Under the influence of 0.5–4 мМ salts of nickel, cobalt, iron (ІІ) and zinc there Tel.: +38067-811-86-44. E-mail: moroz_oksana@yahoo.com DOI: 10.15421/031512 ISSN 1726-1112. Ecology and noospherology. 2015. Vol. 26, no. 1–2 107 are an insignificant changes of absorption spectra of extracted pigments. Under the influence of 1−4 mM Ni, 2−3 mM Fe and 3−4 mM Zn on the curves of 2+ absorption spectra appear maximums in area of 500 nm, 1−2 mM Ni and 0.5−3 мМ Fe − in area of 600 nm. Negative influence of nickel, cobalt, iron (ІІ) and zinc ions at the concentrations of 2.5–4 мМ on pigments formation by cells of Lamprocystis sp. Ya-2003 is discovered. Inhibition by bivalent metals ions of pigments synthesis in purple sulfur bacteria is a considerable obstacle for realization by them of natural detoxication of the lighted zones of technogenic reservoirs from high-toxic hydrogen sulfide in the process of his use as electrons donor of anoxygenic photosynthesis.