Acta microbiologica Polonica最新文献

The antifungal activity of Bacillus coagulans against three pathogenic species of Fusarium was examined. Fungal growth was determined by colony forming units, dry matter and ergosterol level. Biosynthesis of Fusarium mycotoxins was also investigated. The strongest inhibition of fungal growth was noticed when Bacillus coagulans was co-inoculated at the beginning of culture. Estimation of ergosterol level as a determinant of fungal growth showed the greatest degree of Fusarium sp. inhibition. Addition of Bacillus coagulans to Fusarium culmorum culture inhibits the DON (deoxynivalenol) production.

Campylobacter jejuni 72Dz/92 cjaD gene, orthologue of C. jejuni NCTC 11168 cj0113, C. jejuni M275 omp18 and C. jejuni ATCC 29428 omp18, has been cloned, sequenced and analysed from the viewpoint of its immunological attributes. Neither the 5' nor 3' fragment of the cjaD encodes protein capable of reacting with anti-Campylobacter antibodies. Several fusions of the cjaD with eltB, which encodes B subunit of the E. coli LT toxin, have been constructed. The hybrid proteins, which differ in respect to their cellular localization, retain the ability to react with GM1 and are recognized by the antibodies specific for both moieties of the proteins. The fusion protein equipped with signal sequence, reveals a stronger affinity to GM1 than its equivalent which is unable to cross the inner membrane. Two recombinant plasmids (pUWM405 expressing both LTB and CjaD proteins and pUWM299 containing cjaD gene fused into 3' end of Escherichia coli eltB gene lacking signal sequence) were introduced into avirulent Salmonella enterica serovar Typhimurium strain where they are stably maintained.

A novel thermophilic Bacillus sp. capable of producing lipase was locally isolated. Phylogenetic analysis based on 16SrDNA sequence revealed its close relationship to Bacillus thermoleovorans. Plackett-Burman experimental design was used to evaluate cultural conditions affecting lipase production process. Fifteen variables and four dummy variables were examined in the experimental design. Tween 80, temperature, olive oil, aeration, beef extract and inoculum age were found to be the highest positive significant variables affecting lipase activity, whereas pH and calcium chloride were the highest negative significant variables. Moreover, Tween 80, temperature and olive oil positively affected lipase specific activity. On the other hand, gum arabic, inoculum size and calcium chloride had the highest negative effect on lipase specific activity. This study would improve the further optimization steps on the bioprocess development track.

An experiment was designed to determine the role of the chitinase of S. marcescens in controlling the production of zearalenone by F. graminearum isolated from diseased wheat plants. Fusarium graminearum, F. avenaceum, F. equiseti, F. culmorum, and F. solani were isolated from diseased wheat plant. F. graminearum culture materials were highly pathogenic for wheat seedlings, toxic to ducklings and produced high levels of zearalenone. S. marcescens was grown on the cell wall of F. graminearum and its components, chitin and laminarin as a sole carbon source. The release of N-acetyl-D-glucosamine from chitin, F. graminearum cell wall and living or drying mycelium indicated substrate degradation. S. marcescens applied to F. graminearum infested wheat kernels decreased greatly the occurrence of zearalenone after 4 weeks of incubation. F. graminearum culture materials treated with S. marcescens proved to be non-toxic to ducklings and wheat seed germination.

The paper presents the efficiency of phenol removal (concentrations from 500 to 2000 mg/l) by fungi isolated from activated sludge purifying wastewater with high phenol concentration. Five fungal strains were isolated and identified. All isolated strains appeared to be Moniliales from the class of Fungi Imperfecti (Candida sp., Monosporium sp., Trichosporon sp.) Stationary cultures of the individual strains and their mixtures were maintained in Czapek medium containing phenol in concentration from 500 to 2000 mg/l. All isolated strains (except one) were capable of utilising phenol up to a concentration of 1500 mg/l. Depending on investigated strain, phenol in concentration of 500 mg/l was decomposed during 4-25 days, 750 mg/l during 4-14 days. After 20 days, a phenol decline of 1000 mg/l was observed. After 16 days, the phenol decline was 1500 mg/l. Higher phenol concentrations (1500 mg/l) were utilised only by a mixture of two strains. The investigated fungal strains showed good efficiency of phenol removal from high phenol concentration in wastewater and they may be proposed for use in the process of purifying wastewater of this type.

The third oxidation pond at 10th of Ramadan desert receives a number of industrial waste water effluents contaminated with the heavy metal ions Zn, Cd, Cu and Ni. The species diversity and fungal community structure of seven different sites at the onshore sediments and offshore were studied. Mycological analysis resulted in isolation of 3912 fungal colonies, 11.7% of this count were recovered from the onshore sediment sites (4 sites) whereas 88.3% were from the offshore sites (3 sites), in the desert. Fungal counts and species diversity at the onshore sites tend to increase with increasing distance far from the waste water input. A complete accordance was observed among the total fungal counts and species variabilities with organic matter content at each sampling site. This relationship was reversed in case of heavy metal contents with both counts and diversity. Seventeen fungal species belonging to seven genera were isolated from all sites under study. Aspergillus spp. constituted the majority of the isolates (51.7% of the total isolates), followed by Curvularia, Cephalosporium, and Humicola. Of nine isolated Aspergillus spp., A. humicola was the most dominant (37.4% of the total catch) and appeared at all polluted sites. Therefore, A. humicola was chosen to investigate its potential for heavy metals sorption from the contaminated waste water effluent. Four days old biomass pellets could sorb a large amount of heavy metals according to the following sequence: Zn>Cd>Cu>Ni ions. Agitation significantly increased Zn and Cd sorption, but not Cu and Ni. Heavy metals sorption took place at a wide pH range and particularly increased at alkaline pH (8-9).

The aim of this research was to elaborate fast and sensitive method ofdetection of E. coli O157:H7 in food samples. Raw ground meat obtained from retail was artificially inoculated with low numbers of E. coli O157:H7. 18 h enrichment culture allowed pathogenic bacteria to multiply to the levels detectable in multiplex PCR. Immunomagnetic separation with magnetic beads coated with an antibody against E. coli O157:H7 were used to concentrate target bacteria and to separate PCR inhibitors. A portion of the bacterial suspension was used in a multiplex PCR to amplify eae (attaching and effacing) gene, stx (shiga toxin) genes and 90 kbp plasmid. The sensitivity of E. coli O157:H7 detection method was shown to be 1 cfu per 25 g of food sample. The total analysis can be completed within 24 h, whilst traditional methods involves enrichment, direct plating and confirmation tests with entire time at least 3 days.

Umbraviruses are plant viruses that are unusual in that they lack within their genomes information for a capsid protein, and thereby for aphid transmission. They are transmitted by mechanical inoculation, but may become aphid-transmissible when the plants are co-infected with suitable luteoviruses which act as the helper viruses. In mixed infection the umbravirus can be encapsidated by the capsid protein shell provided from the luteovirus helper and, as a result, gain aphid transmissibility. The associations of some umbraviruses with luteoviruses result in specific, lasting disease complexes, showing interesting biological properties. However, umbraviruses are generally not sufficiently recognized, although several of them are significant pathogens in some regions of the world, including Europe. This review describes the development of studies upon umbraviruses and characterizes the genus Umbravirus and its best recognized members.

Pseudomonas vesicularis and Staphylococcus sciuri were isolated as dominant strains from phenol-acclimated activated sludge. P. vesicularis was an efficient degrader of phenol, catechol, p-cresol, sodium benzoate and sodium salicylate in a single substrate system. Under similar conditions S. sciuri degraded only phenol and catechol from among aromatic compounds that were tested. Cell-free extracts of P. vesicularis grown on phenol (376 mg l(-1)), sodium benzoate (576 mg l(-1)) and sodium salicylate (640 mg l(-1)) showed catechol 2,3-dioxygenase activity initiating an extradiol (meta) splitting pathway. The degradative intradiol (ortho) pathway as a result of catechol 1,2-dioxygenase synthesis was induced in P. vesicularis cells grown on catechol (440 mg l(-1)) orp-cresol (432 mg l(-1)). Catechol 1,2-dioxygenase and the ortho-cleavage has been also reported in S. sciuri cells capable of degrading phenol (376 mg l(-1)) or catechol (440 mg l(-1)). In cell-free extracts of S. sciuri no meta-cleavage enzyme activity was detected. These results demonstrated that gram-positive S. sciuri strain was able to effectively metabolize some phenols as do many bacteria of the genus Pseudomonas but have a different capacity for degrading of these compounds.

Eighteen strains of bacteria were isolated from activated sludge purifying petroleum-refining wastewaters. These strains were plated on solidified mineral medium supplemented with oil fraction in concentration 1000 mg/l. Four of the strains that grew best in the presence of oil were selected for further studies. The strains were identified based on Bonde's scheme and microscopic observations. Three of them belonged to the genus Arthrobacter and one to the genus Micrococcus. Stationary cultures of single strains and their mixtures were set up in mineral medium containing oil (sterile and non-sterile) as sole carbon source in concentration 1000 mg/l. The oils were found to be removed the most efficiently by a mixture of the strains. After 14 days of culture the amount of oil was utilized by from 63 to 95%. In the next stage of the studies the bacteria were used to inoculate activated sludge. Stationary cultures of the activated sludge were set up in mineral medium with oil. The utilisation of petroleum products by non-inoculated activated sludge (control), activated sludge inoculated with a single strain or a mixture of all four strains was examined. In both inoculated activated sludge cultures approximately 80% of the oils were removed, compared to 60% in the control activated sludge. Therefore, inoculated activated sludge showed 20% higher effectiveness of removal of petroleum derivatives.