Acta microbiologica Polonica最新文献

A role of autoimmune process and its link with bacterial infections in initiation or aggravation of atherosclerosis symptoms has been suggested. Antigenic mimicry and cross-reactivity of circulating antibodies have been indicated as some major factors in this process. In this study, the prevalence and titers of IgG and IgA antibodies reacting with glycine extract of H. pylori surface antigens were determined immunoenzymatically (ELISA) in the group of patients with unstable ischaemic heart disease and in patients with aggravated dyspepsia. Our results reveal that elevated titers of IgG anti-H. pylori are more typical for cardiac patients and lower prevalence of IgA anti-H. pylori--for those with aggravated dyspepsia. This supports the hypothesis that intensed humoral response in immunoglobulins class G against some bacterial antigens may play a role in the aggravation of symptoms of coronary atherosclerosis.

The 27 gene of bacteriophage T4 has been shown of encode two proteins of 44 and 39 kilodaltons (designated 27-44 and 27-39 bis, respectively) as a result of independent translational initiation at two different start codons within the same reading frame. The first product is the structural component of the viral baseplate. The latter with molecular weight 39 kDa probably plays significant role in regulation of expression of gene 51.

Studies were performed to elucidate the optimal reaction conditions (pH, temperature, ammonia concentration and biocatalyst loading) for bioconversion of trans-cinnamic acid (t-CA) to L-phenylalanine (L-Phe) by L-phenylalanine ammonia lyase (PAL) containing Rhodotorula glutinis cells. All treatments with permeabilizing agents stimulated L-Phe production and also enhanced instability of the catalyst, except Triton X-100 which gave a superior (56%) increase in conversion as compared to the control and a significant stabilization of PAL enzyme. Inclusion of several activity modifiers and stabilizer additives in reaction mixtures were shown to enhance the yield of L-Phe and maintained PAL stability over several successive incubations during the bioconversion process. Maximum stabilization of PAL and enhancement of L-Phe production was achieved with addition of 20% polyhydric alcohol (glycerol). The production of L-Phe continued to the fifth cycle and the total yield increased 2.3 times compared to the yield produced by the control (without glycerol addition) during the repeated batch process. Reducing agents such as 2-mercaptoethanol and thioglycolic acid were added to the bioconversion mixture in order to reduce the effects of oxygen on PAL catalyst life. Production of L-Phe by addition of 400 mgL(-1) of thioglycolic acid was maximized over the control by 55%. When both 20% glycerol and 400 mgL(-1) thioglycolic acid were simultaneously present in the reaction mixture, reuseability and stability of biocatalyst (PAL) were extended to eight consecutive cycles and conversion rate and overall productivity of L-Phe were higher than that of the control. These results may lead to improvements in the production of the essential amino acid L-Phe.

Restricted glucose catabolite repressed mutants of P. stipiti CCY 39501 were selected using UV irradiation. Four mutants were obtained which assimilated glucose slower than the native strain of P. stipitis and the degree of glucose repression was about 2-fold lower for P5-90-133 and P5-200-16 mutants and about 10-fold lower for P5-80-7 and P5-80-35 mutants. P5-80-7 and P5-80-35 produced very small amounts of ethanol from glucose and xylose, whereas P5-90-133 and P5-200-16 fermented sugars at the wild-type level. These two mutants were selected for co-fermentation process with native strain of S. cerevisiae V30 or Ja(a), as well as with their respiratory deficient mutants. During co-culture process of P. stipitis mutants with native strains of S. cerevisiae the ethanol yields obtained ranged from 0.38 to 0.45 g/g, and this alcohol was produced mainly from glucose. But, when also xylose, besides glucose was fermented to ethanol during co-fermentation of both mutant strains, lower yields of ethanol (0.28-0.40 g/g) were obtained.

Pectin methyl esterase (PME) [E.C.3. 1.1.11] production by Curvularia inaequalis (Shear) Boedijn NRRL 13884 was investigated using solid-state culture. The highest level of extracellular pectin methyl esterase was detected with orange peels as an inducing substrate and as a sole carbon source. The enzyme was partially purified using Sephadex G-100 and DEAE-Cellulose column chromatography. It was purified about 40 fold with optimum activity at pH 4.4 and 45 degrees C. The enzyme was activated by Co++, Mg++, Na+, whereas it was slightly activated in the presence of Cu++, K+, Mn++, Zn++. On the other hand Ag++, Ca++ and Hg++ inhibited the activity of the enzyme. The Km was calculated to be 0.52 mM.

Escherichia coli null dnaJ and dnaKdnaJ mutants, when introduced to Hfr donor, impair its ability to DNA transfer during conjugation. The additive effect of both mutations was shown. Lack of DnaK and DnaJ chaperones also decrease the extent of proteolysis in mutant strains. This effect is seen only at 42 degrees C. The influence of double dnaKdnaJ deletion but not single dnaJ deletion on novobiocin susceptibility was also demonstrated.

In this study, the yeast strains were isolated from grapes by serial dilution technique to determine their alcohol-, sugar- and thermotolerance. 34 wild type yeast strains were isolated and alcohol-, sugar- and thermotolerance of these strains were determined. The maximum alcohol tolerance was found to be 9% (v/v) in yeast strain which is named Y2. Thermotolerance behavior of 6 strains were investigated. The strains were treated with UV light with intervals of 20, 30, 40 and 50 seconds. Selected resistant colonies were investigated for alcohol tolerance. It was found that alcohol tolerance increased from 9% (v/v) to 12% (v/v) on Y2 strain.

In this study, the sensitivities of multiplex PCR and an immuno-chromatographic methods to detect Escherichia coli O157:H7 in minced beef were compared. The detection of Escherichia coli O157:H7 in minced beef inoculated with 1-100 cells of this bacterium was possible after enrichment of culture and subsequent analysis by either of the two methods. Enrichment conditions were eight hours of incubation at 37 degrees C or 42 degrees C in a non-selective medium (Buffered Peptone Water). Multiplex PCR analysis was performed using three primer sets with analysis by gel electrophoresis. The Quix immuno-chromatographic assay which is a new kit being marketed by New Horizons Diagnostics, Columbia, MD, was used for immunological analysis of the enriched broths.The sensitivity of both tests was similar. The results depended on the concentration of the specific bacterium in the culture since the influence of the proportion of other bacteria to the E. coli O157:H7 was not observed. The data suggests that either method or used together, when coupled with an enrichment technique, could provide a rapid mean to detect the presence of this pathogen in minced meat samples.

Dinitrogen fixation activity was determined directly on experimental plots in mixtures of grass with red and white clover in the year of sowing as well as in the first year of full utilisation using the method of acetylene reduction (ARA). Furthermore, numbers of bacteria, actinomycetes, fungi and Azotobacter sp. were determined in soils under the experimental mixtures.

Helicobacter pylori resistance to antimicrobial agents is an important factor compromising the efficacy of treatment. Therefore the aims of our study were: to determine the prevalence of H. pylori resistance to clarithromycin, metronidazole, amoxycillin and tetracycline in children prior to eradication therapy, to compare different methods of susceptibility testing and to detect mutations responsible for clarithromycin resistance. During 1996-2000, 259 H. pylori strains were isolated from antral gastric biopsies. Susceptibility to antimicrobials was determined by the agar dilution method and the Etest. Mutations in the 23S rRNA gene associated with clarithromycin resistance were analysed by PCR-RFLP and direct sequencing. Overall, ninety-six strains (37%) were resistant to metronidazole, 50 strains (19.3%) were resistant to clarithromycin, and 20 strains (7.7%) were simultaneously resistant to both drugs. All cultured isolates were sensitive to amoxycillin and only one isolate (0.4%) was resistant to tetracycline. The agar dilution method and the Etest showed a perfect category correlation for clarithromycin and 4% discrepancies for metronidazole. Primary resistance to clarithromycin was mainly associated with an A2143G mutation in the 23S rRNA gene of H. pylori. The study highlights the high prevalence of H. pylori primary resistance to clarithromycin in Polish children, which implies a need for pretreatment susceptibility testing.