Studies on alkalophilic CGTase-producing bacteria and effect of starch on cyclodextrin-glycosyltransferase activity

The production of beta- and gamma -CD by CGTase from Bacillus firmus was studied, in regard to the effect of the source and concentration of starch on the yield of CD and CGTase activity. A cyclic activity of accumulation and consumption of beta -CD and gamma -CD occurred during the bacterial growth. CGTase was more active when citrate buffer, pH 5.5 was used. No differences were found for production of gamma -CD with the use of commercial starch flour when compared with corn starch (p>0.05). The use of commercial starch flour resulted in decreased conversion of starch to beta-CD (all the 4 starch sources were statistically different, p<0.05). The best results for beta -CD production were obtained with the use of corn starch. The specific activity of CGTase was not affected by starch concentration, different source of starch nor by the presence of glutamic acid, a CD-complexing agent

Occurrence of coliforms in water samples of the Perequê and Penedo Rivers in Paraná, Brazil

The Perequê and Penedo rivers flow through the plains of Praia de Leste and fall into the sea between the municipalities of Pontal do Sul and Ponta do Poço. Both of these rivers belong to the sub-basin of Paranaguá Bay, and are constituent parts of the hydrographic basin of the Atlantic Ocean (State of Paraná). Four sites along the Perequê River (Stations 1-4) and one along the Penedo River (Station 5) were monitorated for water pollution over a 12-month period. During the period of December 1995 to November 1996, three water samples were collected from each site, placed in sterilized bottles and transported to the laboratory in ice-boxes. They were analyzed for the occurrence of total and fecal coliforms, temperature and pH. Fecal pollution was detected throughout the period of study. Coliform contamination was smaller in Station 1 and 5 than in any other sites, probably due to lesser influence from urbanized areas. Water at Station 4 was strongly contaminated due to its close proximity to a sewage canal. This study demonstrated that the Pequerê and Penedo rivers, freshwater shrimps habitats, were heavily contaminated with fecal indicator bacteria, and this occurrence was not related with temperature or pH.Os rios Perequê e Penedo têm suas fontes na planície de Praia Leste e fluem para o mar entre os municípios de Pontal do Sul e Ponta do Poço. Ambos pertencem à sub-bacia da Baía de Paranaguá e são partes da bacia hidrográfica do Oceano Atlântico (Estado do Paraná). Foram selecionados quatro sítios ao longo do Rio Perequê (Estações 1-4) e um no Rio Penedo (Estação 5) para monitorar a poluição de água em um período de 12 meses. Durante o período de dezembro de 1995 e novembro de 1996, foram coletadas de cada local, 3 amostras de 100 ml água em frascos esterilizados e transportadas para o laboratório em caixas com gelo. Foram analisadas a ocorrência de coliformes totais (TC) e fecais (FC), temperatura e pH. A contaminação de coliformes foi menor nos sítios 1 e 5 do que em outros locais, provavelmente por causa da menor influência de áreas urbanizadas. A água na estação 4 estava fortemente contaminada por causa de sua proximidade a um canal de esgoto. Este estudo demonstrou que a água dos rios Pequerê e Penedo, "habitats" para várias espécies de camarões de água doce, estão contaminados com coliformes totais e fecais, e esta ocorrência não está relacionada com a temperatura ou pH

Colorimetric determination of alpha and beta-cyclodextrins and studies on optimization of CGTase production from B. firmus using factorial designs

Cyclodextrin glycosyltransferase (EC 2.4.1.19, CGTase) production from B. firmus, isolated from soil of Curitiba, PR, was optimized in shake flask using an experimental design approach. The CGTase was produced when the carbon source was starch and beta-CD, but when simple sugars such as glucose, galactose, lactose, sucrose, and maltose were used, there was no enzyme production. CGTase production was the same with either organic nitrogen or inorganic nitrogen source. CGTase activity decreased 2-fold when incubation temperature was increased from 28 to 37 ° C, and decreased 2.1- fold when the initial pH was lowered from 10.3 to 7.4. The colorimetric determinations of alpha - and beta -CD were analyzed as a non-linear relationship and the equilibrium constant for alpha -CD/methyl orange and beta -CD/phenolphthalein complexes were 7.69 x 10³ L / mol and 2.33 x 10³ L/ mol, respectively

Occurrence of extended-spectrum beta-lactamases in Enterobacteriaceae isolated from hospitalized patients in Curitiba, southern Brazil

Production of extended-spectrum beta-lactamases (ESBL) by enterobacteria is an important resistance mechanism against antimicrobial beta-lactamics. We tested 498 bacterial strains isolated from two tertiary-care teaching hospitals for ESBL production, using screening breakpoints for aztreonam and third generation cephalosporins, according to CLSI recommendations. Among these isolates, 155 were positive for the ESBL screening test, and 121 (78%) were confirmed by the clavulanic acid combination disk method. We found a high frequency of ESBL (24%) among Enterobacteriaceae, with a frequency of 57.4% for Klebsiella pneumoniae, 21.4% for Klebsiella oxytoca, and 7.2% for E. coli. In other members of Enterobacteriaceae, non-Klebsiella and non-E. coli, the prevalence was 21.6%. Ceftriaxone and cefotaxime showed a higher sensitivity in the screening test (99.2%) when compared to ceftazidime, aztreonam and cefpodoxime. However, cefotaxime/cefotaxime plus clavulanic acid showed a higher sensitivity in the confirmatory test (96.7%)