Objective:To isolate yeasts and moulds from selected natural systems and study the effect of tetracycline(Tet)on them so as to generate comprehensive data for further elucidation of transfer or evolutionary developmen...Objective:To isolate yeasts and moulds from selected natural systems and study the effect of tetracycline(Tet)on them so as to generate comprehensive data for further elucidation of transfer or evolutionary development of Tet resistance in general and in these lower eukaryotes in particular.Methods:A total of 139 natural yeasts have been isolated from various ecosystems on potato dextrose agar medium.These along with model yeasts and selected natural and model moulds have been tested for their responses to Tet at various concentrations added to the growth media.The effluxed materials were obtained by vortexing and centrifugation of cells and tested against sensitive bacterium.Results:It was found that Tet efflux was a general feature of natural yeasts and filamentous fungi(moulds)could resist Tet upto a concentration of 5 mg/mL.However,at a very high concentration(10 mg/mL)neither the yeasts nor the moulds could grow indicating that Tet is toxic for these eukaryotes at very high concentrations.The presence of Tet in the medium exaggerates filamentation in all the hyphal forming yeasts.Conclusions:The results suggest efflux as the general mechanism of Tet-resistance in yeasts and moulds possibly acquired from bacteria via horizontal transfer.展开更多
The aim of this work was to investigate the fungal population dynamics in ready-to-eat bagged samples of rocket （Diplotaxis spp.）, lettuce baby leaf （Lactuca sativa L.） and ＂songino＂ （Valerianella olitoria L.）...The aim of this work was to investigate the fungal population dynamics in ready-to-eat bagged samples of rocket （Diplotaxis spp.）, lettuce baby leaf （Lactuca sativa L.） and ＂songino＂ （Valerianella olitoria L.） during a shelf-life, in order to evaluate the effects of the storage length and season of production on the spoilage processes. The incidence of toxigenic moulds was particularity studied in order to evaluate a potential production of mycotoxins and allergenic conidia. A total of 900 samples collected from 10 Italian trademarks were analyzed at the 2nd, 5th and 8th day after the packaging in the spring and summer. A very high number of fungi was found and a great variability of moulds and yeasts at the 1 st day of sampling was observed. Regarding to season of production, any seasonal effect on the moulds and yeasts has been observed, but the moulds detected belonged to different species in relation to season. Regarding to storage length, the yeasts and moulds did not showed significant variations during a shelf-life. In relation to vegetable species, the lettuce resulted always less contaminated with respect to other salads, and the rocket presented 1-2 Log cfu/g of increasing in the level of moulds. Regarding to fungi species, the yeasts were significantly predominant respect to moulds. Finally, the toxigenic moulds Aspergillusflavus and Penicillium italicum were found in all the types of salad in the summer, and their growth during the storage at low temperature represented a potential hazard for the mycotoxins and allergenic conidia production in these commodities.展开更多
With the emergence and spread of antimicrobial resistance(AMR)it becomes pertinent to search for an antimicrobial alternative to cater for the imminent need to control total drug-resistant(TDR)and multiple-drug-resist...With the emergence and spread of antimicrobial resistance(AMR)it becomes pertinent to search for an antimicrobial alternative to cater for the imminent need to control total drug-resistant(TDR)and multiple-drug-resistant(MDR)infections.Antimicrobial peptides(AMPs)have shown some promise and this study was designed to evaluate antimicrobial activity of Moricin(a naturally produced AMP by silkworm,Bombyx mori larvae)against 276 microbial strains of 83 species.Only two(Erwinia amylovora 1,Hafnia alvei 1)strains were classified as susceptible to Moricin at a concentration≤8μg/mL.If susceptibility criteria were set at MIC equivalent to≤128μg/mL then Moricin inhibited 17 strains.All of the Bacillus species strains and majority of the strains of Acinetobacter,Aeromonas,Enterococcus,Erwinia,Raoultella,and Serratia species were significantly(p<0.05)more often resistant(MIC>512μg/mL)to Moricin than strains belonging to Alacligenes,Bacillus,Escherichia,Klebsiella,Pantoea,Pasteurella,Salmonella,Staphylococcus and Streptococcus species.Susceptibility of different bacteria not only varied significantly to Moricin but also to most of the commonly used antibiotics.The susceptibility of microbes not only affected by their type but also by their source of origin.The study concluded that Moricin has a wide spectrum but limited potential to inhibit clinically important microbial strains belonging to different species and genera.展开更多
基金Supported by Madhya Pradesh Council of Science and Technology,Bhopal(Grant No.3902/CST/R&D/2011).
文摘Objective:To isolate yeasts and moulds from selected natural systems and study the effect of tetracycline(Tet)on them so as to generate comprehensive data for further elucidation of transfer or evolutionary development of Tet resistance in general and in these lower eukaryotes in particular.Methods:A total of 139 natural yeasts have been isolated from various ecosystems on potato dextrose agar medium.These along with model yeasts and selected natural and model moulds have been tested for their responses to Tet at various concentrations added to the growth media.The effluxed materials were obtained by vortexing and centrifugation of cells and tested against sensitive bacterium.Results:It was found that Tet efflux was a general feature of natural yeasts and filamentous fungi(moulds)could resist Tet upto a concentration of 5 mg/mL.However,at a very high concentration(10 mg/mL)neither the yeasts nor the moulds could grow indicating that Tet is toxic for these eukaryotes at very high concentrations.The presence of Tet in the medium exaggerates filamentation in all the hyphal forming yeasts.Conclusions:The results suggest efflux as the general mechanism of Tet-resistance in yeasts and moulds possibly acquired from bacteria via horizontal transfer.
文摘The aim of this work was to investigate the fungal population dynamics in ready-to-eat bagged samples of rocket （Diplotaxis spp.）, lettuce baby leaf （Lactuca sativa L.） and ＂songino＂ （Valerianella olitoria L.） during a shelf-life, in order to evaluate the effects of the storage length and season of production on the spoilage processes. The incidence of toxigenic moulds was particularity studied in order to evaluate a potential production of mycotoxins and allergenic conidia. A total of 900 samples collected from 10 Italian trademarks were analyzed at the 2nd, 5th and 8th day after the packaging in the spring and summer. A very high number of fungi was found and a great variability of moulds and yeasts at the 1 st day of sampling was observed. Regarding to season of production, any seasonal effect on the moulds and yeasts has been observed, but the moulds detected belonged to different species in relation to season. Regarding to storage length, the yeasts and moulds did not showed significant variations during a shelf-life. In relation to vegetable species, the lettuce resulted always less contaminated with respect to other salads, and the rocket presented 1-2 Log cfu/g of increasing in the level of moulds. Regarding to fungi species, the yeasts were significantly predominant respect to moulds. Finally, the toxigenic moulds Aspergillusflavus and Penicillium italicum were found in all the types of salad in the summer, and their growth during the storage at low temperature represented a potential hazard for the mycotoxins and allergenic conidia production in these commodities.
基金The research work was supported by grants received from CAAST-ACLH(No.NAHEP/CAAST/2018-19)of ICAR-World Bank-funded National Agricultural Higher Education Project(NAHEP).
文摘With the emergence and spread of antimicrobial resistance(AMR)it becomes pertinent to search for an antimicrobial alternative to cater for the imminent need to control total drug-resistant(TDR)and multiple-drug-resistant(MDR)infections.Antimicrobial peptides(AMPs)have shown some promise and this study was designed to evaluate antimicrobial activity of Moricin(a naturally produced AMP by silkworm,Bombyx mori larvae)against 276 microbial strains of 83 species.Only two(Erwinia amylovora 1,Hafnia alvei 1)strains were classified as susceptible to Moricin at a concentration≤8μg/mL.If susceptibility criteria were set at MIC equivalent to≤128μg/mL then Moricin inhibited 17 strains.All of the Bacillus species strains and majority of the strains of Acinetobacter,Aeromonas,Enterococcus,Erwinia,Raoultella,and Serratia species were significantly(p<0.05)more often resistant(MIC>512μg/mL)to Moricin than strains belonging to Alacligenes,Bacillus,Escherichia,Klebsiella,Pantoea,Pasteurella,Salmonella,Staphylococcus and Streptococcus species.Susceptibility of different bacteria not only varied significantly to Moricin but also to most of the commonly used antibiotics.The susceptibility of microbes not only affected by their type but also by their source of origin.The study concluded that Moricin has a wide spectrum but limited potential to inhibit clinically important microbial strains belonging to different species and genera.
