All previously reported bacterial species which are capable of lysing harmful algae have been isolated from coastal environments in which harmful algae blooms have occurred. Due to the low concentration of alga-lysing...All previously reported bacterial species which are capable of lysing harmful algae have been isolated from coastal environments in which harmful algae blooms have occurred. Due to the low concentration of alga-lysing bacteria in an algal bloom, it is difficult to isolate the alga-lysing bacteria by existing methods. In this paper, two algae-lysing bacterial strains, P01 and P03, have been isolated from a biosystem immobilized on a sponge that was highly effective in removing algae and microcystins. Their lysing modes and effects on Microcystis aeruginosa have been studied. The results show that the degradation processes of these two strains for M. aeruginosa accorded with a first-order reaction model when the chlorophylla concentration was in the range from 0 to 1000 μgL-1. The degradation rate constants were 0.1067, 0.1274 and 0.2792 for P01 and0.0683, 0.0744 and 0.028 97 for P03, when the bacterial densities were 8.6 × 105, 8.6 × 106 and 8.6 × 107cells mL-1 respectively. Moreover, the two bacterial strains had favourable lytic effects not only on M. aeruginosa , but also on Chlorella and Scene-desmus. Their lytic effect on M. aeruginosa did not require physical cell to cell contact, but proceeded by the production of an extracellular product. The bacterial strains were identified as Bacillus species by PCR amplification of the 16S rRNA gene, BLAST analysis, and comparison with sequences in the GenBank nucleotide database.展开更多
The epidemiology of Salmonella involves food, especially meat and dairy products. These have a high salmonella outbreak in the summer. The majority of Salmonella enteritis in young children occurs in the form of scatt...The epidemiology of Salmonella involves food, especially meat and dairy products. These have a high salmonella outbreak in the summer. The majority of Salmonella enteritis in young children occurs in the form of scattered cases. At least 25% of summer gastroenteritis in young children is caused by Salmonella. In Western Europe, S. typhimurium accounts for nearly 70% of isolates. The objective of this study was to investigate the Salmonella contaminating meat and dairy products as well as define the percentages of contamination by Salmonella from 2004 to 2006, by the Department of Hygiene of Tunis. For this study, we collected samples in various motherboard solutions, and conducted a pre-nonselective enrichment in selective enrichment in isolation and identification and ultimately biochemical confirmation. One hundred and sixty two samples, 125 samples of meat products including 68 samples of red meat （beef and sheep, beef, offal and Merguez） and 57 samples of poultry （chicken and turkey）, 37 samples of milk products which included 32 samples of cheese and five samples milk, were analysed microbiologically from 2004 to 2006, in the Health Service in Tunis. These analyses include the detection and enumeration of Salmonella. From 2004 to 2006, the rate of infections by the Salmonella, meat and dairy products were： 55.9% for red meat, 71.9% for poultry, 68.8% for cheeses, 40% for milk. The meat of poultry is contaminated with Salmonella that the cheeses, which are more than red meats, which are also more contaminated than milk. This might be due to a lack of hygiene throughout the circuit processing （slaughter, transport, processing, etc.）. The increased risk of contamination of milk products by Salmonella is proportional to the manipulation done on these products. The latter must be handled by pasteurization and sterilization.展开更多
Wheat ranks first among cereal crops cultivated in the world. In its production, diseases like powdery mildew, fusarium head blight and rusts caused by fungal pathogens represent a major problem. They produce differen...Wheat ranks first among cereal crops cultivated in the world. In its production, diseases like powdery mildew, fusarium head blight and rusts caused by fungal pathogens represent a major problem. They produce different symptoms that cause severe crop damage by infecting the spikes, leaves, roots, stems and grains. They are causing losses both by reducing the quantity of the harvested crop and the quality of the product. Quality problems of the harvested product can be due to shrivelled seed, which are frequently found as a consequence of the infection by leaf pathogens, such as mildews, rusts and Septoria. Fusarium head blight is the major culprit for mycotoxin contamination from the harvested grain, causing economic losses and in the worst casing human and animal health problems. In severe epidemics, all these fungal diseases can significantly reduce yield. Resistance to fungi is beneficial not only from a commercial point of view （yield）, but also because of the reduced levels of mycotoxins. The integration of transgenic approaches offers a potential chemical-free and environment-friendly solution for controlling fungal pathogens. This is an essential asset for wheat world food security.展开更多
基金This study was supported by the Sino Japan Science Cooperative Program （Grant No.003250103） Special Funds for PhD Research Station of University （Grant No. 20020422045）Science Foundation of Shandong Province （Grant No. Z2003B01 ）.
文摘All previously reported bacterial species which are capable of lysing harmful algae have been isolated from coastal environments in which harmful algae blooms have occurred. Due to the low concentration of alga-lysing bacteria in an algal bloom, it is difficult to isolate the alga-lysing bacteria by existing methods. In this paper, two algae-lysing bacterial strains, P01 and P03, have been isolated from a biosystem immobilized on a sponge that was highly effective in removing algae and microcystins. Their lysing modes and effects on Microcystis aeruginosa have been studied. The results show that the degradation processes of these two strains for M. aeruginosa accorded with a first-order reaction model when the chlorophylla concentration was in the range from 0 to 1000 μgL-1. The degradation rate constants were 0.1067, 0.1274 and 0.2792 for P01 and0.0683, 0.0744 and 0.028 97 for P03, when the bacterial densities were 8.6 × 105, 8.6 × 106 and 8.6 × 107cells mL-1 respectively. Moreover, the two bacterial strains had favourable lytic effects not only on M. aeruginosa , but also on Chlorella and Scene-desmus. Their lytic effect on M. aeruginosa did not require physical cell to cell contact, but proceeded by the production of an extracellular product. The bacterial strains were identified as Bacillus species by PCR amplification of the 16S rRNA gene, BLAST analysis, and comparison with sequences in the GenBank nucleotide database.
文摘The epidemiology of Salmonella involves food, especially meat and dairy products. These have a high salmonella outbreak in the summer. The majority of Salmonella enteritis in young children occurs in the form of scattered cases. At least 25% of summer gastroenteritis in young children is caused by Salmonella. In Western Europe, S. typhimurium accounts for nearly 70% of isolates. The objective of this study was to investigate the Salmonella contaminating meat and dairy products as well as define the percentages of contamination by Salmonella from 2004 to 2006, by the Department of Hygiene of Tunis. For this study, we collected samples in various motherboard solutions, and conducted a pre-nonselective enrichment in selective enrichment in isolation and identification and ultimately biochemical confirmation. One hundred and sixty two samples, 125 samples of meat products including 68 samples of red meat （beef and sheep, beef, offal and Merguez） and 57 samples of poultry （chicken and turkey）, 37 samples of milk products which included 32 samples of cheese and five samples milk, were analysed microbiologically from 2004 to 2006, in the Health Service in Tunis. These analyses include the detection and enumeration of Salmonella. From 2004 to 2006, the rate of infections by the Salmonella, meat and dairy products were： 55.9% for red meat, 71.9% for poultry, 68.8% for cheeses, 40% for milk. The meat of poultry is contaminated with Salmonella that the cheeses, which are more than red meats, which are also more contaminated than milk. This might be due to a lack of hygiene throughout the circuit processing （slaughter, transport, processing, etc.）. The increased risk of contamination of milk products by Salmonella is proportional to the manipulation done on these products. The latter must be handled by pasteurization and sterilization.
文摘Wheat ranks first among cereal crops cultivated in the world. In its production, diseases like powdery mildew, fusarium head blight and rusts caused by fungal pathogens represent a major problem. They produce different symptoms that cause severe crop damage by infecting the spikes, leaves, roots, stems and grains. They are causing losses both by reducing the quantity of the harvested crop and the quality of the product. Quality problems of the harvested product can be due to shrivelled seed, which are frequently found as a consequence of the infection by leaf pathogens, such as mildews, rusts and Septoria. Fusarium head blight is the major culprit for mycotoxin contamination from the harvested grain, causing economic losses and in the worst casing human and animal health problems. In severe epidemics, all these fungal diseases can significantly reduce yield. Resistance to fungi is beneficial not only from a commercial point of view （yield）, but also because of the reduced levels of mycotoxins. The integration of transgenic approaches offers a potential chemical-free and environment-friendly solution for controlling fungal pathogens. This is an essential asset for wheat world food security.
