Pub Date : 1996-07-01DOI: 10.1111/j.1365-2672.1996.tb03276.x
J D Monk, L R Beuchat, A K Hathcox
The effects of sucrose esters of fatty acids, alone and in combination with ethylenediaminetetraacetic acid (EDTA), acetic acid, lactic acid and citric acid, on survival, growth and thermal inactivation of Listeria monocytogenes and Staphylococcus aureus were determined. The presence of sucrose monocaprate (400 micrograms ml-1) in tryptose phosphate broth (TPB) or tryptic soy broth (TSB) did not inhibit the growth of L. monocytogenes or Staph. aureus, respectively. However, significantly (P < or = 0.05) lower populations of L. monocytogenes were detected in TPB containing as little as 100 micrograms ml-1 sucrose monolaurate (SML) during the logarithmic growth phase compared to populations detected in TPB containing no SML. At 400 micrograms ml-1, SML was lethal to L. monocytogenes. Less marked inhibitory effects were observed with Staph. aureus. The addition of EDTA to broth containing SML had a synergistic effect on the inhibition of both organisms. The chelator alone had no effect at 100 micrograms ml-1 on either pathogen but was inhibitory at 200 micrograms ml-1. Inhibition of L. monocytogenes was more pronounced as the incubation temperature was decreased from 30 degrees C to 15 or 5 degrees C. The addition of 0.1% acetic or lactic acid to TPB minimized the inhibitory effect of 100 and 200 micrograms ml-1 SML during the first 32 h of incubation. Staphylococcus aureus behaved similarly, but not as dramatically, to L. monocytogenes when cultured in TSB supplemented with SML alone or SML and organic acids. A synergistic inhibitory effect of SML and EDTA on heat inactivation of L. monocytogenes was evident but the reverse phenomenon was observed with Staph. aureus. The effectiveness of SML in controlling the growth of L. monocytogenes and Staph. aureus in foods most likely to be contaminated with these pathogens should be further investigated.
{"title":"Inhibitory effects of sucrose monolaurate, alone and in combination with organic acids, on Listeria monocytogenes and Staphylococcus aureus.","authors":"J D Monk, L R Beuchat, A K Hathcox","doi":"10.1111/j.1365-2672.1996.tb03276.x","DOIUrl":"https://doi.org/10.1111/j.1365-2672.1996.tb03276.x","url":null,"abstract":"<p><p>The effects of sucrose esters of fatty acids, alone and in combination with ethylenediaminetetraacetic acid (EDTA), acetic acid, lactic acid and citric acid, on survival, growth and thermal inactivation of Listeria monocytogenes and Staphylococcus aureus were determined. The presence of sucrose monocaprate (400 micrograms ml-1) in tryptose phosphate broth (TPB) or tryptic soy broth (TSB) did not inhibit the growth of L. monocytogenes or Staph. aureus, respectively. However, significantly (P < or = 0.05) lower populations of L. monocytogenes were detected in TPB containing as little as 100 micrograms ml-1 sucrose monolaurate (SML) during the logarithmic growth phase compared to populations detected in TPB containing no SML. At 400 micrograms ml-1, SML was lethal to L. monocytogenes. Less marked inhibitory effects were observed with Staph. aureus. The addition of EDTA to broth containing SML had a synergistic effect on the inhibition of both organisms. The chelator alone had no effect at 100 micrograms ml-1 on either pathogen but was inhibitory at 200 micrograms ml-1. Inhibition of L. monocytogenes was more pronounced as the incubation temperature was decreased from 30 degrees C to 15 or 5 degrees C. The addition of 0.1% acetic or lactic acid to TPB minimized the inhibitory effect of 100 and 200 micrograms ml-1 SML during the first 32 h of incubation. Staphylococcus aureus behaved similarly, but not as dramatically, to L. monocytogenes when cultured in TSB supplemented with SML alone or SML and organic acids. A synergistic inhibitory effect of SML and EDTA on heat inactivation of L. monocytogenes was evident but the reverse phenomenon was observed with Staph. aureus. The effectiveness of SML in controlling the growth of L. monocytogenes and Staph. aureus in foods most likely to be contaminated with these pathogens should be further investigated.</p>","PeriodicalId":22599,"journal":{"name":"The Journal of applied bacteriology","volume":"81 1","pages":"7-18"},"PeriodicalIF":0.0,"publicationDate":"1996-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1111/j.1365-2672.1996.tb03276.x","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"19651176","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1996-06-01DOI: 10.1111/j.1365-2672.1996.tb03266.x
P D Franzmann, B M Patterson, T R Power, P D Nichols, G B Davis
The city of Perth contains a number of sites that have been contaminated with hydrocarbons due to leakage from petroleum underground storage tanks. Microbial biomass in groundwater and sediment cores from above and below the water table, and from within and outside a plume of hydrocarbon contamination, was examined using phospholipid fatty acid methyl ester analysis. Microbial numbers, calculated from the phospholipid content, ranged from 0.9 x 10(6) to 7.8 x 10(6) 'Escherichia coli equivalent cells' g-1 dry wt of sediment. Over 96% of the microbial biomass was attached to the sediment and the proportion of attached cells did not decrease within the plume of contaminants. The amount of biomass within aquifer samples seemed to be related more to the proximity of the rhizosphere to the shallow aquifer, and other unknown urban inputs, rather than to the effects of the plume of contaminants. Fatty acids common to many bacterial groups dominated within the plume, and as such the analyses gave limited insight into microbial community structure. For site assessment of intrinsic remediation of shallow aquifers in urban areas, estimates of microbial biomass may not provide information that is readily applicable to plume management.
{"title":"Microbial biomass in a shallow, urban aquifer contaminated with aromatic hydrocarbons: analysis by phospholipid fatty acid content and composition.","authors":"P D Franzmann, B M Patterson, T R Power, P D Nichols, G B Davis","doi":"10.1111/j.1365-2672.1996.tb03266.x","DOIUrl":"https://doi.org/10.1111/j.1365-2672.1996.tb03266.x","url":null,"abstract":"<p><p>The city of Perth contains a number of sites that have been contaminated with hydrocarbons due to leakage from petroleum underground storage tanks. Microbial biomass in groundwater and sediment cores from above and below the water table, and from within and outside a plume of hydrocarbon contamination, was examined using phospholipid fatty acid methyl ester analysis. Microbial numbers, calculated from the phospholipid content, ranged from 0.9 x 10(6) to 7.8 x 10(6) 'Escherichia coli equivalent cells' g-1 dry wt of sediment. Over 96% of the microbial biomass was attached to the sediment and the proportion of attached cells did not decrease within the plume of contaminants. The amount of biomass within aquifer samples seemed to be related more to the proximity of the rhizosphere to the shallow aquifer, and other unknown urban inputs, rather than to the effects of the plume of contaminants. Fatty acids common to many bacterial groups dominated within the plume, and as such the analyses gave limited insight into microbial community structure. For site assessment of intrinsic remediation of shallow aquifers in urban areas, estimates of microbial biomass may not provide information that is readily applicable to plume management.</p>","PeriodicalId":22599,"journal":{"name":"The Journal of applied bacteriology","volume":"80 6","pages":"617-25"},"PeriodicalIF":0.0,"publicationDate":"1996-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1111/j.1365-2672.1996.tb03266.x","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"19672713","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1996-06-01DOI: 10.1111/j.1365-2672.1996.tb03268.x
J Huang, C Lacroix, H Daba, R E Simard
Continuous production of pediocin 5 from Pediococcus acidilactici UL5 was investigated in MRS medium at different pH and dilution rates during continuous free cell (FC) and immobilized cell (IC) fermentations. Pediocin 5 activity from FC operated at a dilution rate of 0.31 h-1 largely increased from 128 to 2048 AU mL-1 as pH decreased from 7.0 to 5.0. Pediocin 5 activity in IC at a dilution rate of 0.93 h-1 was much less affected by pH, varying from 256 AU mL-1 at pH 7.0 to 512 AU mL-1 at pH 5.0. At the optimum pH 5.0, the dilution rate greatly influenced pediocin 5 activity both in FC and IC. Pediocin 5 production during continuous FC culture decreased with time for all dilution rates tested except 0.31 h-1 and average activity over 144 h cultures reached a maximal value of 4915 AU mL-1 at a dilution rate of 0.26 h-1. For IC, pediocin 5 production was stable with time and increased with the dilution rate from 256 to 1024 AU mL-1 in the range of 0.47-2.28 h-1. Three Listeria strains were tested for their ability to screen low bacteriocin-producing variants (Bac+v) of Bac+ cells in FC and IC cultures by using a modified deferred antagonism method. Ten to 28% of Bac+v cells appeared after 144 h of FC cultures at dilution rates in the range 0.09-0.42 h-1 and pH control set points of 5.0-7.0 while almost no Bac+v cell was detected during 192 h IC culture in the same pH range and for dilution rates varying from 0.47 to 2.28 h-1. The Bac+v cells isolated produced eight- to 64-fold less pediocin 5 than the Bac+ cells. Although electrophoresis analysis showed no apparent difference in the plasmid profiles of Bac+v and Bac+ cells, the Bac- mutant obtained by acriflavine treatment had lost the pMJ5 plasmid encoding for bacteriocin production. The decreased quantity of plasmid DNA in Bac+v cells suggests that the decreased pediocin 5 activity of Bac+v cells resulted from a decrease in plasmid copy number.
在不同pH和稀释率的MRS培养基中,研究了由嗜酸Pediococcus acidilactii UL5在连续游离细胞(FC)和固定化细胞(IC)发酵过程中连续生产pediocin 5的情况。在0.31 h-1稀释率下,当pH从7.0降低到5.0时,FC的Pediocin 5活性从128 AU mL-1增加到2048 AU mL-1。当稀释率为0.93 h-1时,IC中的Pediocin 5活性受pH的影响较小,从pH 7.0时的256 AU mL-1到pH 5.0时的512 AU mL-1。在最佳pH 5.0时,稀释率对FC和IC中pediocin 5的活性都有很大影响。除0.31 h-1外,FC连续培养过程中,所有稀释率的pediocin 5产量都随着时间的推移而下降,在0.26 h-1的稀释率下,培养144 h的平均活性达到最大值4915 AU mL-1。在0.47 ~ 2.28 h-1范围内,稀释率为256 ~ 1024 AU mL-1时,弓形虫素5的产量随时间稳定而增加。采用改进的递延拮抗方法,对三株李斯特菌菌株在FC和IC培养物中筛选Bac+细胞的低产菌素变体(Bac+v)的能力进行了测试。在0.09-0.42 h-1的稀释率和5.0-7.0的pH控制设定值范围内,FC培养144小时后出现10 - 28%的Bac+v细胞,而在相同的pH范围和0.47 - 2.28 h-1的稀释率范围内,IC培养192小时后几乎没有检测到Bac+v细胞。分离的Bac+v细胞产生的pediocin 5比Bac+细胞少8 - 64倍。虽然电泳分析显示Bac+v和Bac+细胞的质粒谱没有明显差异,但经吖啶黄碱处理获得的Bac-突变体失去了编码细菌素产生的pMJ5质粒。Bac+v细胞的质粒DNA数量减少,表明Bac+v细胞的pediocin 5活性降低是由于质粒拷贝数减少所致。
{"title":"Pediocin 5 production and plasmid stability during continuous free and immobilized cell cultures of Pediococcus acidilactici UL5.","authors":"J Huang, C Lacroix, H Daba, R E Simard","doi":"10.1111/j.1365-2672.1996.tb03268.x","DOIUrl":"https://doi.org/10.1111/j.1365-2672.1996.tb03268.x","url":null,"abstract":"<p><p>Continuous production of pediocin 5 from Pediococcus acidilactici UL5 was investigated in MRS medium at different pH and dilution rates during continuous free cell (FC) and immobilized cell (IC) fermentations. Pediocin 5 activity from FC operated at a dilution rate of 0.31 h-1 largely increased from 128 to 2048 AU mL-1 as pH decreased from 7.0 to 5.0. Pediocin 5 activity in IC at a dilution rate of 0.93 h-1 was much less affected by pH, varying from 256 AU mL-1 at pH 7.0 to 512 AU mL-1 at pH 5.0. At the optimum pH 5.0, the dilution rate greatly influenced pediocin 5 activity both in FC and IC. Pediocin 5 production during continuous FC culture decreased with time for all dilution rates tested except 0.31 h-1 and average activity over 144 h cultures reached a maximal value of 4915 AU mL-1 at a dilution rate of 0.26 h-1. For IC, pediocin 5 production was stable with time and increased with the dilution rate from 256 to 1024 AU mL-1 in the range of 0.47-2.28 h-1. Three Listeria strains were tested for their ability to screen low bacteriocin-producing variants (Bac+v) of Bac+ cells in FC and IC cultures by using a modified deferred antagonism method. Ten to 28% of Bac+v cells appeared after 144 h of FC cultures at dilution rates in the range 0.09-0.42 h-1 and pH control set points of 5.0-7.0 while almost no Bac+v cell was detected during 192 h IC culture in the same pH range and for dilution rates varying from 0.47 to 2.28 h-1. The Bac+v cells isolated produced eight- to 64-fold less pediocin 5 than the Bac+ cells. Although electrophoresis analysis showed no apparent difference in the plasmid profiles of Bac+v and Bac+ cells, the Bac- mutant obtained by acriflavine treatment had lost the pMJ5 plasmid encoding for bacteriocin production. The decreased quantity of plasmid DNA in Bac+v cells suggests that the decreased pediocin 5 activity of Bac+v cells resulted from a decrease in plasmid copy number.</p>","PeriodicalId":22599,"journal":{"name":"The Journal of applied bacteriology","volume":"80 6","pages":"635-44"},"PeriodicalIF":0.0,"publicationDate":"1996-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1111/j.1365-2672.1996.tb03268.x","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"19672715","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1996-06-01DOI: 10.1111/j.1365-2672.1996.tb03265.x
R Zaccone, G Caruso, M Azzaro
The autotrophic ammonium-oxidizing bacterium Nitrosococcus oceanus was studied in the brackish lake of Ganzirri by cultural and immunofluorescent methods. The preparation of the specific antiserum in rabbits is reported. The polyclonal antiserum for Nitrosococcus oceanus cross-reacted with other ammonia oxidizing strains, but not with other marine bacteria. Temporal changes were determined by taking monthly water samples from a station 6 m deep and the distribution in sediments was investigated in four stations. Isolation of a strain of Nitrosococcus sp. was obtained from a sediment sample collected in December. The abundance of Nitrosococcus spp. bacteria correlated positively with particulate organic carbon (POC), particulate organic nitrogen (PON), temperature and total bacteria, whereas there was a negative relationship with oxygen tension. No correlation was found between immunofluorescent and MPN counts of Nitrosococcus spp. bacteria.
{"title":"Detection of Nitrosococcus oceanus in a Mediterranean lagoon by immunofluorescence.","authors":"R Zaccone, G Caruso, M Azzaro","doi":"10.1111/j.1365-2672.1996.tb03265.x","DOIUrl":"https://doi.org/10.1111/j.1365-2672.1996.tb03265.x","url":null,"abstract":"<p><p>The autotrophic ammonium-oxidizing bacterium Nitrosococcus oceanus was studied in the brackish lake of Ganzirri by cultural and immunofluorescent methods. The preparation of the specific antiserum in rabbits is reported. The polyclonal antiserum for Nitrosococcus oceanus cross-reacted with other ammonia oxidizing strains, but not with other marine bacteria. Temporal changes were determined by taking monthly water samples from a station 6 m deep and the distribution in sediments was investigated in four stations. Isolation of a strain of Nitrosococcus sp. was obtained from a sediment sample collected in December. The abundance of Nitrosococcus spp. bacteria correlated positively with particulate organic carbon (POC), particulate organic nitrogen (PON), temperature and total bacteria, whereas there was a negative relationship with oxygen tension. No correlation was found between immunofluorescent and MPN counts of Nitrosococcus spp. bacteria.</p>","PeriodicalId":22599,"journal":{"name":"The Journal of applied bacteriology","volume":"80 6","pages":"611-6"},"PeriodicalIF":0.0,"publicationDate":"1996-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1111/j.1365-2672.1996.tb03265.x","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"19672711","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1996-06-01DOI: 10.1111/j.1365-2672.1996.tb03263.x
E A Herrera, O Pérez, M Segovia
A multiplex-polymerase chain reaction (PCR) assay, based on one-step amplification and detection of three different mycobacterial genomic fragments, was designed for differentiation between Mycobacterium bovis and Mycobacterium tuberculosis. The oligonucleotide primers were chosen from the groEL gene, present in the genus Mycobacterium sp., from the IS6110 insertion sequence, present in Myco. tuberculosis complex and from the mtp40 gene, identified as a specific-species Myco. tuberculosis genomic fragment. This amplification method allowed the detection of two fragments of 576 and 317 base pairs in Myco. bovis and three fragments of 576, 396 and 317 base pairs in Myco. tuberculosis strains, including atypical strains of Myco. tuberculosis where the copy number of the IS6110 element is low. The multiplex-PCR assay described may be a very useful tool for the rapid and specific differentiation of these related mycobacteria and easy to use in medical and veterinary microbiology laboratories.
{"title":"Differentiation between Mycobacterium tuberculosis and Mycobacterium bovis by a multiplex-polymerase chain reaction.","authors":"E A Herrera, O Pérez, M Segovia","doi":"10.1111/j.1365-2672.1996.tb03263.x","DOIUrl":"https://doi.org/10.1111/j.1365-2672.1996.tb03263.x","url":null,"abstract":"<p><p>A multiplex-polymerase chain reaction (PCR) assay, based on one-step amplification and detection of three different mycobacterial genomic fragments, was designed for differentiation between Mycobacterium bovis and Mycobacterium tuberculosis. The oligonucleotide primers were chosen from the groEL gene, present in the genus Mycobacterium sp., from the IS6110 insertion sequence, present in Myco. tuberculosis complex and from the mtp40 gene, identified as a specific-species Myco. tuberculosis genomic fragment. This amplification method allowed the detection of two fragments of 576 and 317 base pairs in Myco. bovis and three fragments of 576, 396 and 317 base pairs in Myco. tuberculosis strains, including atypical strains of Myco. tuberculosis where the copy number of the IS6110 element is low. The multiplex-PCR assay described may be a very useful tool for the rapid and specific differentiation of these related mycobacteria and easy to use in medical and veterinary microbiology laboratories.</p>","PeriodicalId":22599,"journal":{"name":"The Journal of applied bacteriology","volume":"80 6","pages":"596-604"},"PeriodicalIF":0.0,"publicationDate":"1996-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1111/j.1365-2672.1996.tb03263.x","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"19672710","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1996-06-01DOI: 10.1111/j.1365-2672.1996.tb03267.x
M Qiao, S Ye, O Koponen, R Ra, M Usabiaga, T Immonen, P E Saris
The antibiotic peptide nisin produced by Lactococcus lactis is used as a food preservative due to its activity against spores and vegetative cells of Gram-positive bacteria. The post-translational maturation of this secreted peptide includes dehydration of serine and threonine residues, lanthionine formation and a proteolytic processing of 23 amino acids from the N-terminus. Mutations in the nisZ, nisB and nisP genes of the biosynthetic nisZBTCIPRK nisin operon were made by gene replacement or integration of a plasmid. The mutations caused a drastic decrease of the transcription from the promoters upstream of the nisZBTCIPRK and nisFEG operons resulting in loss of nisin production and nisin immunity. The transcription of the nisin operons and nisin immunity could be partially restored by adding nisin to the growth medium of the cells. Nisin induction of the mutant strains also increased the level of the putative immunity NisI protein. These results showed that the nisZBTCIPRK operon is positively autoregulated and that the nisFEG operon is in the same regulon.
{"title":"Regulation of the nisin operons in Lactococcus lactis N8.","authors":"M Qiao, S Ye, O Koponen, R Ra, M Usabiaga, T Immonen, P E Saris","doi":"10.1111/j.1365-2672.1996.tb03267.x","DOIUrl":"https://doi.org/10.1111/j.1365-2672.1996.tb03267.x","url":null,"abstract":"<p><p>The antibiotic peptide nisin produced by Lactococcus lactis is used as a food preservative due to its activity against spores and vegetative cells of Gram-positive bacteria. The post-translational maturation of this secreted peptide includes dehydration of serine and threonine residues, lanthionine formation and a proteolytic processing of 23 amino acids from the N-terminus. Mutations in the nisZ, nisB and nisP genes of the biosynthetic nisZBTCIPRK nisin operon were made by gene replacement or integration of a plasmid. The mutations caused a drastic decrease of the transcription from the promoters upstream of the nisZBTCIPRK and nisFEG operons resulting in loss of nisin production and nisin immunity. The transcription of the nisin operons and nisin immunity could be partially restored by adding nisin to the growth medium of the cells. Nisin induction of the mutant strains also increased the level of the putative immunity NisI protein. These results showed that the nisZBTCIPRK operon is positively autoregulated and that the nisFEG operon is in the same regulon.</p>","PeriodicalId":22599,"journal":{"name":"The Journal of applied bacteriology","volume":"80 6","pages":"626-34"},"PeriodicalIF":0.0,"publicationDate":"1996-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1111/j.1365-2672.1996.tb03267.x","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"19672714","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1996-06-01DOI: 10.1111/j.1365-2672.1996.tb03264.x
J Y Maillard, T S Beggs, M J Day, R A Hudson, A D Russell
The coliphage K1-5 has been used in an automated assay to monitor the viricidal activity of various disinfectants. This indirect assay based on the spectrophotometric reading of the lysis of the host cell (Escherichia coli D837) produced encouraging results and was faster than the overlay counting method (previously studied) which relies on plaque formation. However, differences in sensitivity towards some disinfectants were observed between the two methods.
{"title":"The use of an automated assay to assess phage survival after a biocidal treatment.","authors":"J Y Maillard, T S Beggs, M J Day, R A Hudson, A D Russell","doi":"10.1111/j.1365-2672.1996.tb03264.x","DOIUrl":"https://doi.org/10.1111/j.1365-2672.1996.tb03264.x","url":null,"abstract":"<p><p>The coliphage K1-5 has been used in an automated assay to monitor the viricidal activity of various disinfectants. This indirect assay based on the spectrophotometric reading of the lysis of the host cell (Escherichia coli D837) produced encouraging results and was faster than the overlay counting method (previously studied) which relies on plaque formation. However, differences in sensitivity towards some disinfectants were observed between the two methods.</p>","PeriodicalId":22599,"journal":{"name":"The Journal of applied bacteriology","volume":"80 6","pages":"605-10"},"PeriodicalIF":0.0,"publicationDate":"1996-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1111/j.1365-2672.1996.tb03264.x","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"19672712","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1996-06-01DOI: 10.1111/j.1365-2672.1996.tb03260.x
W Fang
A fluorimetric technique was compared with the plate counting method for quantification of viable cells of Staphylococcus aureus and Escherichia coli in the liquid medium. The fluorimetric assay measures the release of fluorogenic 4-methylumbelliferone (4-MU) from 4-methylumbelliferyl phosphate by the bacterial phosphatases. The increase in fluorescence was dependent on the size of bacterial inocula. Setting the fluorescence threshold at the middle of the logarithmic growth phase resulted in good linear relationship between bacterial counts and fluorescence (r = 0.99 for both Staph. aureus and E. coli). There was also an excellent correlation between the fluorimetric assay and the plate counting method in quantifying viable bacteria in saline (r = 0.99). Both methods were further compared for evaluation of extracellular bacteria following phagocytosis. The fluorimetric technique, in general, gave a higher percentage of phagocytosis than the plate counting method with statistical significance for E. coli.
{"title":"Quantification of Staphylococcus aureus and Escherichia coli in the liquid medium by fluorimetry and its use in phagocytosis assay.","authors":"W Fang","doi":"10.1111/j.1365-2672.1996.tb03260.x","DOIUrl":"https://doi.org/10.1111/j.1365-2672.1996.tb03260.x","url":null,"abstract":"<p><p>A fluorimetric technique was compared with the plate counting method for quantification of viable cells of Staphylococcus aureus and Escherichia coli in the liquid medium. The fluorimetric assay measures the release of fluorogenic 4-methylumbelliferone (4-MU) from 4-methylumbelliferyl phosphate by the bacterial phosphatases. The increase in fluorescence was dependent on the size of bacterial inocula. Setting the fluorescence threshold at the middle of the logarithmic growth phase resulted in good linear relationship between bacterial counts and fluorescence (r = 0.99 for both Staph. aureus and E. coli). There was also an excellent correlation between the fluorimetric assay and the plate counting method in quantifying viable bacteria in saline (r = 0.99). Both methods were further compared for evaluation of extracellular bacteria following phagocytosis. The fluorimetric technique, in general, gave a higher percentage of phagocytosis than the plate counting method with statistical significance for E. coli.</p>","PeriodicalId":22599,"journal":{"name":"The Journal of applied bacteriology","volume":"80 6","pages":"577-82"},"PeriodicalIF":0.0,"publicationDate":"1996-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1111/j.1365-2672.1996.tb03260.x","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"19672811","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1996-06-01DOI: 10.1111/j.1365-2672.1996.tb03262.x
L Gram, J Melchiorsen
The interaction between fish spoilage bacteria, Pseudomonas sp. and Shewanella putrefaciens, was investigated using fish extract and fish tissue as model systems. Isolates of Pseudomonas that produced iron chelators, siderophores, inhibited growth of S. putrefaciens in a fish-extract-agar diffusion assay but no, or only weak, antagonistic activity was seen when the medium was supplemented with iron. Sterile-filtered supernatant fluid from a siderophore-producing Pseudomonas grown in fish extract was inhibitory to S. putrefaciens if the number of Psudomonas was above 10(8) cfu ml-1. In contrast, supernatant fluids from siderophore-negative Pseudomonas isolates did not inhibit growth of S. putrefaciens. The inhibitory effect was, except for one strain of Pseudomonas, not seen in supernatant fluids from iron-enriched cultures of Pseudomonas sp. Finally, siderophore-producing Pseudomonas sp. lowered the maximum cell level of S. putrefaciens 1-2 log units from 10(9) to 10(10) cfu g-1 when the strains were grown on fish muscle blocks at 0 degrees C but the growth rate of S. putrefaciens was not affected.
{"title":"Interaction between fish spoilage bacteria Pseudomonas sp. and Shewanella putrefaciens in fish extracts and on fish tissue.","authors":"L Gram, J Melchiorsen","doi":"10.1111/j.1365-2672.1996.tb03262.x","DOIUrl":"https://doi.org/10.1111/j.1365-2672.1996.tb03262.x","url":null,"abstract":"<p><p>The interaction between fish spoilage bacteria, Pseudomonas sp. and Shewanella putrefaciens, was investigated using fish extract and fish tissue as model systems. Isolates of Pseudomonas that produced iron chelators, siderophores, inhibited growth of S. putrefaciens in a fish-extract-agar diffusion assay but no, or only weak, antagonistic activity was seen when the medium was supplemented with iron. Sterile-filtered supernatant fluid from a siderophore-producing Pseudomonas grown in fish extract was inhibitory to S. putrefaciens if the number of Psudomonas was above 10(8) cfu ml-1. In contrast, supernatant fluids from siderophore-negative Pseudomonas isolates did not inhibit growth of S. putrefaciens. The inhibitory effect was, except for one strain of Pseudomonas, not seen in supernatant fluids from iron-enriched cultures of Pseudomonas sp. Finally, siderophore-producing Pseudomonas sp. lowered the maximum cell level of S. putrefaciens 1-2 log units from 10(9) to 10(10) cfu g-1 when the strains were grown on fish muscle blocks at 0 degrees C but the growth rate of S. putrefaciens was not affected.</p>","PeriodicalId":22599,"journal":{"name":"The Journal of applied bacteriology","volume":"80 6","pages":"589-95"},"PeriodicalIF":0.0,"publicationDate":"1996-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1111/j.1365-2672.1996.tb03262.x","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"19672812","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1996-06-01DOI: 10.1111/j.1365-2672.1996.tb03269.x
S T Aspinall, D R Wareing, P G Hayward, D N Hutchinson
The newly developed CAT campylobacter selective medium employing the blood-free charcoal-based agar containing cefoperazone (8 mg l-1), amphotericin (10 mg l-1) and teicoplanin (4 mg l-1) was compared with the membrane filtration culture technique for isolation of Campylobacter spp. including Camp. upsaliensis. Nine hundred and fifty human, 275 dog and 65 cat faeces (in which modified CCDA medium was also compared) were tested. In addition, the recovery of Camp. upsaliensis from pure cultures and from spiked human faeces was examined after membrane filtration. A 50-fold reduction in recovery after filtration using the 0.65 micron filters and a 150-fold reduction using the 0.45 micron filters was found. Recovery of Camp. upsaliensis from spiked faeces was considerably improved using the CAT medium compared with filtration, especially with the lower concentration of organisms (approx. 10(4) cfu mL-1). Campylobacter upsaliensis was recovered from 91 specimens of animal faeces, with CCDA recovering 26 isolates (29%), CAT recovering 76 isolates (84%) and membrane filtration (0.65 microns) recovering 82 isolates (90%). CAT selective agar was found to be a suitable medium for the isolation of thermophilic campylobacters including Camp. upsaliensis from faecal samples.
{"title":"A comparison of a new campylobacter selective medium (CAT) with membrane filtration for the isolation of thermophilic campylobacters including Campylobacter upsaliensis.","authors":"S T Aspinall, D R Wareing, P G Hayward, D N Hutchinson","doi":"10.1111/j.1365-2672.1996.tb03269.x","DOIUrl":"https://doi.org/10.1111/j.1365-2672.1996.tb03269.x","url":null,"abstract":"<p><p>The newly developed CAT campylobacter selective medium employing the blood-free charcoal-based agar containing cefoperazone (8 mg l-1), amphotericin (10 mg l-1) and teicoplanin (4 mg l-1) was compared with the membrane filtration culture technique for isolation of Campylobacter spp. including Camp. upsaliensis. Nine hundred and fifty human, 275 dog and 65 cat faeces (in which modified CCDA medium was also compared) were tested. In addition, the recovery of Camp. upsaliensis from pure cultures and from spiked human faeces was examined after membrane filtration. A 50-fold reduction in recovery after filtration using the 0.65 micron filters and a 150-fold reduction using the 0.45 micron filters was found. Recovery of Camp. upsaliensis from spiked faeces was considerably improved using the CAT medium compared with filtration, especially with the lower concentration of organisms (approx. 10(4) cfu mL-1). Campylobacter upsaliensis was recovered from 91 specimens of animal faeces, with CCDA recovering 26 isolates (29%), CAT recovering 76 isolates (84%) and membrane filtration (0.65 microns) recovering 82 isolates (90%). CAT selective agar was found to be a suitable medium for the isolation of thermophilic campylobacters including Camp. upsaliensis from faecal samples.</p>","PeriodicalId":22599,"journal":{"name":"The Journal of applied bacteriology","volume":"80 6","pages":"645-50"},"PeriodicalIF":0.0,"publicationDate":"1996-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1111/j.1365-2672.1996.tb03269.x","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"19672716","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}