Use of CHROMagar in the Differentiation of Common Species of <Emphasis Type="Italic">Candida</Emphasis>

CHROMagar has been reported to be useful for the rapid and accurate identification of Candida species. We tested 135 isolates of Candida species isolated from oropharyngeal candidiasis in HIV patients and found that it was useful in the presumptive identification of Candida albicans and Candida krusei. Occasional strains of C. tropicalis produced colonies with a greenish tinge making it difficult to differentiate from C. albicans.     

Composition of activated sludge settling and planktonic bacterial communities treating industrial effluent and their correlation to settling problems

Problems with deflocculation and solids separation in biological wastewater treatment systems are linked to fluctuations in physicochemical conditions. This study examined the composition of activated sludge bacterial communities in lab-scale sequencing batch reactors treating bleached kraft mill effluent, under transient temperature conditions (30 to 45 °C) and their correlation to sludge settleability problems. The bacterial community composition of settled and planktonic biomass samples in the reactors was monitored via denaturing gradient gel electrophoresis of 16S ribosomal RNA gene fragments. Our analysis showed that settled biomass has a different community composition from the planktonic biomass (49 ± 7% difference based on Jaccard similarity coefficients; p < 0.01). During times of poor sludge compression, the settled and planktonic biomass became more similar. This observation supports the hypothesis that settling problems observed were due to deflocculation of normally settling flocs rather than the outgrowth of non-settling bacterial species.     

Evaluation of a mixed bacterial culture for de-emulsification of water-in-petroleum oil emulsions

A mixed bacterial culture, isolated from a petroleum-contaminated site, was evaluated for its de-emulsification capabilities using a kerosene–water model emulsion system and petroleum oilfield emulsion. The culture exhibited high de-emulsification activity with 96% de-emulsification of a water-in-oil emulsion within 24 h. Nine morphologically distinct pure colonies were isolated from the mixed culture and identified and their de-emulsification capabilities were tested. All three strains of Acinetobacter, i.e. A. calcoaceticus, A. calcoaceticus BV ALC and A. radioresistans were capable of providing > 90% de-emulsification, while Pseudomonas aeruginosa, P. carboxydohydrogena, and Alcaligenes latus showed > 80% de-emulsification. Different de-emulsification patterns were observed between species of Acinetobacter and Pseudomonas. The mixed culture exhibited higher de-emulsifier activity, as compared to the most effective pure culture, Acinetobacter calcoaceticus, when de-emulsification ability was tested on an oilfield water-in-oil emulsion.