Ham Petrol, Sondaj Çamuru Ve Çamur Çukurundan İzole Edilen Mikroorganizmalar İle Petrol Biyoyıkımının Araştırılması

Abstract

In this study, the aim was the isolation, identification and biodegradation of petroleum by microorganisms which exist in crude oil, drilling fluid and mud pit as well as petroleum biodegradation with these strains. It was determined that Proteus mirabilis, Bacillus cereus, Bacillus subtilis, Enterococcus faecalis were isolated from crude oil; Bacillus subtilis subsp. spizizenii, Bacillus cereus, Enterococcus faecalis were isolated from mud pit and Proteus mirabilis, Klebsiella pneumoniae, Bacillus tequilensis, Bacillus axarquiensis, Enterobacter cloacae strains were isolated from drilling fluid. Petroleum biodegradation rates of microorganisms, which were isolated and identified, were compared. In this regard, K. pneumoniae with 59.5 % and B. axarquiensis with 50.5 % were identified as the most effective stains in petroleum biodegradation and selected to be used in continuation of this study. For both strains, most effective physical conditions for petroleum biodegradation were determined as pH 7, petroleum concentration 1 % (v/v), culture concentration 2 %, rotation speed 150 rpm, at 25 0C and 7 days. Biodegradation rates of 66.5 % for K. pneumoniae and 65.0 % for B. axarquiensis were obtained under the above-mentioned physical conditions. When the effect of several surfactants (Triton X:100, Tween 80, Tween 20), which increase emulsification of petroleum in the medium, on petroleum biodegradation were investigated, in the presence of Triton X:100 as surfactant source, biodegradation rates of 68 % for K. pneumoniae and 66 % for B. axarquiensis were determined. In addition, biosurfactant production was determined in K. pneumoniae and B. axarquiensis strains with drop-collapse and oil displacement methods. Also, with addition of different carbon sources (glucose, lactose, maltose, sucrose), it was determined that glucose increased petroleum biodegradation of K. pneumoniae to 71 % and maltose increased petroleum biodegradation of B. axarquiensis to 73 %. Furthermore, with addition of nitrogen sources (yeast extract, urea, NH4NO3, (NH4)2SO4, NaNO3, KNO3, NH4H2PO4); yeast extract increased petroleum biodegradation of K. pneumoniae to 72.5 % and NaNO3 increased petroleum biodegradation of B. axarquiensis to 74 %. When effect of mixed culture on petroleum biodegradation was investigated, it was determined that mixed culture of K. pneumoniae and B. axarquiensis did not have significant effect on petroleum biodegradation (74 %). Low biodegradation rate (21.5 %) was determined for mixed culture of strains isolated from crude oil; biodegradation rates of 68 % and 73 % were determined for mixed cultures of strains isolated from mud pit and drilling fluid, respectively. When biodegradation of petroleum in soil samples with 1 % crude oil was investigated, petroleum biodegradations were; for K. pneumoniae 46 % in sterile soil and 61.5 % in nonsterile soil; for B. axarquiensis 32 % in sterile soil and 57.5 % in nonsterile soil and mixed culture of these strains 50.5 % in sterile soil and 78.5 % in nonsterile soil. When petroleum biodegradation in seawater samples including 1 % petroleum was investigated; efficient biodegradation was not obtained and very low growth densities were determined for K. pneumoniae and B. axarquiensis. In last stage of our study, when petroleum biodegradation of K. pneumoniae was investigated with gas chromatography (CG) analysis, biodegradation rates above 90 % for hydrocarbons ranging from C10 and C20 and biodegradation rates above 75 % for hydrocarbons ranging from C20 and C22, were determined.