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Rhizobium lexuminosarum bv. trifolii produces an acidic exopolysac- charide (EPS) which plays an important role in the development of nitrogen-fixing nodules. Tn5 mutant of R. trifolii <>3 defective in EPS production (Exo") forms ineffective (Fix-) nodules on red clover. This Exo mutation is comple­mented by the pARF1368 and pARF25c<>Miiid.s isolated fnuii bank of Rhizobium trifolii TA1, but the complementation is not correlated with restoration of Fix* phenotypt-. Furthermore, these cosmids intro­duced to wild-type of R. trifolii 24 repress its ability to form nitrogen- -fixing nodules. These results might suggest that bacteria with cosmids carrying the exo region form FPS of altered structure. It has been shown by 'll-n.m.r. that exopolysaccharides produced by R. trifolii 93pARF- 1368 and 93pARF25 contain less non-carbohydrate residues (acetyl, pyruvyl and 3-hydroxybutanoyl) than the wild type KPS. These data suggest that the biological activity of the exopolysaccharide of R. trifolii depends on the contents of the non-carbohydrate substitutions.
The potential role of currency in the spread of pathogenic microflora has been evaluated in many countries. In this study Polish paper notes and the coins in general circulation were assayed for the presence of cultivable bacteria and fungi. Bacterial isolates identification was based on cultural and biochemical characters and by comparison of the 16S rRNA gene sequence. Fungal isolates were recognized with biochemical and morphological criteria. Coagulase-negative staphylococci, (43.6% of the total bacterial count) including Staphylococcus saprophyticus, S. epidermidis, and S. hominis, and Enteroccus spp. (30.8% of the total bacterial count), i.e. E. faecalis, E. faecium and E. durans, were the most numerous bacterial contamination. Penicillium spp., and Aspergillus spp. were the most frequently detected moulds whereas Candida spp. was the most frequent yeast isolated from currency. A visible dependence between the banknote denomination, the physical condition of paper currency, and the number of bacteria and fungi was found. The overall count of bacteria isolated from currency was thousand-fold higher than that of fungal isolates. The total amount of bacteria and fungi recovered from the coins was approximately 2.7-fold lower than that isolated from the notes. In summary, the Polish currency notes were found to be contaminated mainly with commensal bacteria and fungi while the opportunistic pathogenic microorganisms Escherichia coli, Pseudomonas stutzeri and C. albicans were detected at a low frequency.
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