First Case of Psychrobacter sanguinis Bacteremia in a Korean Patient / 대한임상미생물학회지

Psychrobacter sanguinis has been described as a Gram-negative, aerobic coccobacilli originally isolated from environments and seaweed samples. To date, 6 cases of P. sanguinis infection have been reported. A 53-year-old male was admitted with a generalized tonic seizure lasting for 1 minute with loss of consciousness and a mild fever of 37.8℃. A Gram stain revealed Gram-negative, small, and coccobacilli-shaped bacteria on blood culture. Automated microbiology analyzer identification using the BD BACTEC FX (BD Diagnostics, Germany) and VITEK2 (bioMérieux, France) systems indicated the presence of Methylobacterium spp., Aeromonas salmonicida, and the Moraxella group with low discrimination. The GenBank Basic Local Alignment Search Tool and an Ez-Taxon database search revealed that the 16S rRNA gene sequence of the isolate showed 99.30% and 99.88% homology to 859 base-pairs of the corresponding sequences of P. sanguinis, respectively (GenBank accession numbers JX501674.1 and HM212667.1). To the best of our knowledge, this is the first human case of P. sanguinis bacteremia in Korea. It is notable that we identified a case based on blood specimens that previously had been misidentified by a commercially automated identification analyzer. We utilized 16S rRNA gene sequencing as a secondary method for correctly identifying this microorganism.

Application of Taguchi design and Response Surface Methodology for improving conversion of isoeugenol into vanillin by resting cells of Psychrobacter sp. CSW4

For all industrial processes, modelling, optimisation and control are the keys to enhance productivity and ensure product quality. In the current study, the optimization of process parameters for improving the conversion of isoeugenol to vanillin by Psychrobacter sp. CSW4 was investigated by means of Taguchi approach and Box-Behnken statistical design under resting cell conditions. Taguchi design was employed for screening the significant variables in the bioconversion medium. Sequentially, Box-Behnken design experiments under Response Surface Methodology [RSM] was used for further optimization. Four factors [isoeugenol, NaCl, biomass and tween 80 initial concentrations], which have significant effects on vanillin yield, were selected from ten variables by Taguchi experimental design. With the regression coefficient analysis in the Box-Behnken design, a relationship between vanillin production and four significant variables was obtained, and the optimum levels of the four variables were as follows: initial isoeugenol concentration 6.5 g/L, initial tween 80 concentration 0.89 g/L, initial NaCl concentration 113.2 g/L and initial biomass concentration 6.27 g/L. Under these optimized conditions, the maximum predicted concentration of vanillin was 2.25 g/L. These optimized values of the factors were validated in a triplicate shaking flask study and an average of 2.19 g/L for vanillin, which corresponded to a molar yield 36.3%, after a 24 h bioconversion was obtained. The present work is the first one reporting the application of Taguchi design and Response surface methodology for optimizing bioconversion of isoeugenol into vanillin under resting cell conditions