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Polyhydroxyalkanoates (PHAs) are especially interesting because of their similar properties to synthetic plastics and their potential use as biodegradable polymers. Many strategies have been employed to effectively and economically produce PHAs, among them a production process based on mixed microbial populations, enriched from activated sludge could be one of the alternative technologies. Defining the bacterial species creating these anonymous populations is crucial for the improvement of cultivation strategy. Moreover, enriched bacterial populations could be a promising source for microbes, useful in many biotechnological projects. The main object of this study was to characterize the microorganisms creating the microbial consortium cultured towards PHAs production. After cultivation, bacteria were identified using the 16S rRNA gene sequencing approach. The presence of genes engaged in PHAs synthesis was detected using PCR. The performed analysis revealed that among eleven isolated bacterial strains, four possessed the ability of polyhydroxybutyrate synthesis.
Two different extracellular lipases were isolated and purified from Pseudomonas aeruginosa Ps-x to apparent homogeneity using ammonium sulfate precipitation followed by ion exchange chromatography on Q- and S-Sepharose column. Both of the purified lipases are monomeric protein with molecular weight of 15.5 and 54.97 KDa respectively. The optimal activities of the enzymes were at 45 and 50°C and pHs 10.0 and 9.0. Calcium ions increase thermostability of both purified lipases I and II. The purified lipase I showed no metal ion dependence for its activity since EDTA up to 10 mM has no effect on the enzyme activity. However purified lipase II showed slight inhibition by EDTA at the same concentration. Moreover, a serine protease inhibitor, PMSF showed an inhibitoiy effect on both purified enzymes.
Neorickettsia is a genus of intracellular bacteria endosymbiotic in digeneans that may also invade cells of vertebrates and are known to cause diseases of wildlife and humans. Herein, we report results of screening for Neorickettsia of an extensive collection of DNA extracts from adult and larval digeneans obtained from various vertebrates and mollusks in the United States. Seven isolates of Neorickettsia were detected by PCR and sequenced targeting a 527 bp long region of 16S rRNA. Sequence comparison and phylogenetic analysis demonstrated that four isolates matched published sequences of Neorickettsia risticii. Three other isolates, provisionally named “catfish agents 1 and 2” (obtained from Megalogonia ictaluri and Phyllodistomum lacustri, both parasitic in catfishes) and Neorickettsia sp. (obtained from cercariae of Diplostomum sp.), differed from previously known genotypes of Neorickettsia and are likely candidates for new species. All 7 isolates of Neorickettsia were obtained from digenean species and genera that were not previously reported as hosts of these bacteria. Members of four digenean families (Dicrocoeliidae, Heronimidae, Macroderoididae and Gorgoderidae) are reported as hosts of Neorickettsia for the first time. Our study reveals several new pathways of Neorickettsia circulation in nature. We have found for the first time a Neorickettsia from a digenean (dicrocoeliid Conspicuum icteridorum) with an entirely terrestrial life cycle. We found N. risticii in digeneans (Alloglossidium corti and Heronimus mollis) with entirely aquatic life cycles. Previously, this Neorickettsia species was known only from digeneans with aquatic/terrestrial life cycles. Our results suggest that our current knowledge of the diversity, host associations and circulation of neorickettsiae is far from satisfactory.
Określono częstość występowania szczepów wytwarzających 16S rRNA me- tylazę ArmA wśród pałeczek z rodziny Enterobacteriaceae wyosobnionych z materiału klinicznego od ludzi w jednym z warszawskich szpitali. Wśród 270 izolatów pałeczek Enterobacteriaceae wyosobnionych od 259 pacjentów wykryto 19 izolatów (7,0%) opornych przynajmniej na dwa spośród wybranych aminoglikozydów (gentamicyna, amikacyna, kanamycyna). U tych izolatów testem PCR poszukiwano genów związanych z wytwarzaniem 16S rRNA metylaz ArmA, RmtB i RmtC. Gen armA wykryto u sześciu (2,2%) izolatów należących do gatunków Enterobacter cloacae (n=4), Klebsiella pneumoniae (n=1) i Proteus mirabilis (n=1). Izolaty te charakteryzowały się wartościami MIC w zakresie 128-1024 µg/ml dla wszystkich badanych aminoglikozydów z grupy 4,6-dwupodstawionych 2-deoksystreptamin.
Określono udział szczepów opornych na wybrane aminoglikozydy (gentami- cyna, amikacyna, netylmycyna, tobramycyna i neomycyna) u 2359 izolatów pałeczek Enterobacteriaceae wyosobnionych z materiału klinicznego od pacjentek szpitala ginekologiczno-położniczego i od noworodków. Oporność na jeden lub więcej z wymienionych antybiotyków stwierdzono u 45 izolatów (1,90%), z czego 33 (73,33%) należało do gatunku Escherichia coli. W metodzie dyfuzyjne—krążkowej 14 izolatów (31,11%) wykazywało wzrost do krawędzi krążka z gentamicyną (10 µg), w tym 7 izolatów charakteryzowało się wartością MIC w zakresie od 256 do 1024 µg/ml, jednakże u tych izolatów nie stwierdzono obecności 16S rRNAmetylaz Arm A, RmtB lub RrmtC. Uzyskane wyniki wskazują na nieznaczny udział szczepów opornych na aminoglikozydy wśród pałeczek Enterobacteriaceae występujących u kobiet w okresie okołoporodowym i mogą świadczyć o znikomym rozprzestrzenieniu pałeczek wytwarzających 16S rRNA metylazy w populacji.
The main goal of this study was to determine the distribution of potentially toxic cyanobacteria in 39 selected Polish water bodies. From the water bodies with blooms and also from those in which blooms were not visible 87 samples were investigated. For the first time samples from ponds localized in villages with high agricultural activities were included. Lakes for which microcystin concentrations had been determined before were included as a reference for the research. The detection of cyanobacteria was conducted by microscopic observation as well as by PCR amplification of the rpoC1 gene fragment. Cyanobacteria were present in 75 out of 87 samples. The presence of potentially toxic cyanobacteria was detected by amplification of the mcyB and mcyE genes, which are involved in the biosynthesis of microcystins. Both genes were detected in 7 out of 9 blooms investigated. In the case of samples collected from water bodies in which blooms were not observed, the mcyB and mcyE genes were detected in 20 out of 36. In order to identify the cyanobacteria occurring in selected reservoirs, 16S plus ITS clone libraries were constructed. The method allowed distinguishing 18 different genotypes. After sequence analysis, cyanobacteria belonging to genera Microcystis, Planktothrix, Anabaena, Pseudanabaena, Synechocystis, Synechococcus and Woronichinia were identified. Results confirmed the usefulness of the rpoC1 and mcy genes for monitoring water bodies and detection of potentially toxic cyanobacteria. Application of molecular markers allowed detecting potentially toxic cyanobacteria before the bloom was visible. This is the first comprehensive study concerning cyanobacteria present in different types of Polish water bodies performed using molecular markers.
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