ABSTRACT
A lipase producing Acinetobacter haemolyticus TA106 was isolated from healthy human skin of tribal population. The maximum activity of 55 U/ml was observed after medium optimization using the “one variable at a time” and the statistical approaches. The optimal composition of the medium was determined as (% w/v or v/v): tryptone - 1, yeast extract - 0.5, sodium chloride-1, olive oil-1, Tween - 80 1, manganese sulphate - 5 mM, sucrose- 1, pH-7. It was found that maximum production occurred in late log phase i.e. after 72 h and at 200 rpm. From factorial design and statistical analysis, it was found that pH, temperature, salt, inoculum density and aeration significantly affected the lipase production. It was also noted that inoculum density of 3 % (v/v), sucrose (1% w/v) and manganese sulphate (5 mM) displayed maximum lipase activity of 55 U/ml by conventional as well as statistical method. Optimization studies also indicated the increase in specific activity from 0.2 U/mg to 6.7 U/mg.
ABSTRACT
Six Acinetobacter sp. isolated from healthy human skin were checked for the production of bioemulsifier. Optimization studies indicated that Luria Bertani broth pH 7 supplemented with calcium chloride (1%) was the optimum medium. Temperature at 37°C was optimum and inducer oils in the medium did not enhance bioemulsifier production. Partial purification of bioemulsifier and chemical analysis revealed that it is a proteoglycan with protein (53%), polysaccharide (43%) and lipid (2%). Maximum emulsification activity obtained was 400 EU/ml. Thin layer chromatography revealed the presence of mannose and rhamnose sugar and oleic and palmitic acids as parts of lipids. The yield obtained was 1.9 g / l. Reconstitution studies revealed that the protein and polysaccharide fractions together display 94.55% of emulsification activity. It was also noted that the bioemulsifier was stable for 72 hr at 37°C and displayed good cleaning property towards different oils. The partially purified bioemulsifier formed stable oil-in-water emulsions with plant oils.
ABSTRACT
BACKGROUND & OBJECTIVE: Acinetobacter spp., the only Gram negative commensal found on human skin are emerging nosocomial pathogens, and are rapidly developing multiple drug resistance. Most studies in India and over the world are on clinical and environmental Acinetobacter isolates. The present investigation was undertaken to study plasmid distribution and antibiotic resistance profile of Acinetobacter genospecies isolated from healthy human skin of a tribal population from western India. METHODS: One hundred and eighteen strains of Acinetobacter spp. were isolated from healthy human skin and biochemically classified into nine genospecies. Plasmid profiles were determined using four standard methods with minor modifications and by a commercial kit. Molecular weights were determined by comparison with standard plasmids pUC19, pBR322, RP4 and molecular weight marker, V517. Antimicrobial susceptibility patterns of Acinetobacter genospecies to 30 antibiotics belonging to different groups was determined using Kirby Bauer method. RESULTS: All isolates, except two showed a maximum of three plasmids with molecular size 1.5 to 40 kb. Five different plasmid types were observed. Only eight strains had one or two stably maintained low molecular weight plasmids in addition to 40 kb plasmid seen in most of the strains. Quinolones and aminoglycosides were most active group followed by, cephalosporins and beta lactams. INTERPRETATION & CONCLUSION: Acinetobacter spp. isolated from the tribal skin flora had low number of plasmids as compared to clinical and environmental isolates. Acinetobacter spp. harbouring low molecular weight plasmids were found to be sensitive to most of the antibiotics tested suggesting these might be coding for some other novel properties or may be cryptic, whereas, those having 40 kb plasmid showed intermediate to low level resistance to some antibiotics.