[EFFECT OF CULTIVATION CONDITION OF ACINETOBACTER CAL COACETICUS IMV B-7241 ON ANTIADHESIVE PROPERTIES OF SURFACTANTS].

AIM: To study the effect of growth factors and microelements in composition of ethanol-, n-hexadecane- and glycerol-containing media on antiadhesive properties of A cinetobacter calcoaceticus IMV B-7241 surfactants. METHODS: Surfactants were extracted from supernatant of cultural liquid by mixture of chloroform and methanol (2:1). The number (%) of attached cells (adhesion) was determined as a ratio of the optical density of the suspension obtained from the materials treated with surfactants to the optical density of the control samples (100 %). RESULTS: Dependence of surfactants antiadhesive properties on presence in the medium of A. calcoaceticus IMB B-7241 cultivation of growth factors and certain microelements, as well as the nature of the carbon source was established. Adhesion of bacteria (Escherichia coli IEM- 1, Bacillus subtilis BT-2) and yeast (Candida albicans D-6) on plastic, dutch tile, linoleum, and steel was a minimal (25-35 %) after surface treatment with surfactant (0.005 mg/ml) synthesized on ethanol in the presence of yeast autolysate and microelements. Replacement the yeast autolysate and microelement mixture in the composition of ethanol- and n-hexadecane-containing media by copper sulfate and iron sulfate and in the medium with glycerol by KCl, zinc sulfate and copper sulfate accompanied by decreasing antiadhesive properties of synthesized surfactants. CONCLUSIONS: The obtained data indicate that the increasing surfactant synthesis does not always the accompanied by the formation of product with the required biological properties and indicate the need for studies depending on biological properties of surfactants of the cultivation conditions of producer.

Cellular fatty acids as chemical markers for differentiation of Acinetobacter baumannii and Acinetobacter calcoaceticus.

OBJECTIVE: Gas chromatography (GC) was used to investigate the cellular fatty acid (CFA) composition of 141 Acinetobacter baumannii and 32 A. calcoaceticus isolates from different locations in China and to find chemical markers to differentiate these two closely related bacteria. METHODS: Whole cell fatty acid methyl esters (FAMEs) were obtained by saponification, methylation, and extraction for GC analysis, followed by a standardized Microbial Identification System (MIS) analysis. RESULTS: All A. baumannii and A. calcoaceticus strains contained some major fatty acids, namely, 18:1 ω9c, 16:0, Sum In Feature 3, 12:0, 17:1ω8c, 3-OH-12:0, 17:0, Sum In Feature 2, 2-OH-12:0, and 18:0 compounds. Although most of the total CFAs are similar between A. baumannii and A. calcoaceticus strains, the ratios of two pairs of CFAs, i.e., Sum In Feature 3/18:1 ω9c versus 16:0/18:1 ω9c and Sum In Feature 3/18:1 ω9c versus unknown 12.484/18:1 ω9c fatty acids, could differentiate these two closely related bacteria. A. baumannii could be easily classified into two subgroups by plotting some ratios such as Sum In Feature 3/16:0 versus 17:0 and Sum In Feature 3/2-OH-12:0 versus 17:0 fatty acids. CONCLUSION: The ratios of some CFAs could be used as chemical markers to distinguish A. baumannii from A. calcoaceticus.

Application of a novel method for optimization of bioemulsan production in a miniaturized bioreactor.

A novel and economical method was used to optimize bacterial growth and bioemulsan production. Acinetobacter calcoaceticus PTCC 1641 was applied in an innovated synthetic medium comprised whey and mineral salt medium (MSM) in ratio of 1:1 in a shaken flask bioreactor. The optimum inoculum size, shaking frequency rate and filling volume (V(L)) using ventilation flasks were investigated that resulted in 5 vol.%, 300 rpm and 15 ml), respectively. The surface tension decreased around 48% during bioemulsan production. Due to determine bioemulsan properties, the reliability of blood agar method was confirmed as well.

Single-culture aerobic granules with Acinetobacter calcoaceticus.

Aerobic granules are cultivated by a single bacterial strain, Acinetobacter calcoaceticus, in a sequencing batch reactor (SBR). This strain presents as a good phenol reducer and an efficient auto coagulator in the presence of phenol, mediated by heat-sensitive adhesins proteins. Stable 2.3-mm granules were formed in the SBR following a 7-week cultivation. These granules exhibit excellent settling attributes and degrade phenol efficiently at concentrations of 250-2,000 mg l(-1). The corresponding phenol degradation rate reached 993.6 mg phenol g(-1) volatile suspended solids (VSS) day(-1) at 250 mg l(-1) phenol and 519.3 mg phenol g(-1) VSS day(-1) at 2,000 mg l(-1) phenol concentration. Meanwhile, free A. calcoaceticus cells were fully inhibited at phenol>1,500 mg l(-1). Denaturing gradient gel electrophoresis fingerprint profile demonstrated no genetic modification in the strain during aerobic granulation. The present single-strain granules showed long-term structural stability and performed high phenol degrading capacity and high phenol tolerance. The confocal laser scanning microscopic test revealed that live A. calcoaceticus cells principally distributed at 200-250 microm beneath the outer surface, with an extracellular polymeric substance layer covering them to defend phenol toxicity. Autoaggregation assay tests demonstrated the possibly significant role of secreted proteins on the formation of single-culture A. calcoaceticus granules.