Abstract

Aims: To study the effects of competitive microbiota, temperature and nutrient availability on Salmonella , Enterococcus , Campylobacter spores of sulphite reducing anaerobes and bacteriophages MS2 and PhiX174 in sediments from a greywater treatment system.Methods and Results: Standard culture methods were used. Bacteria died off rapidly under normal conditions (20degreesC, competitive microbiota) but remained stable or grew in the other conditions studied. When the sediments became nutrient depleted after 2 weeks, a log-linear die-off was observed for Salmonella, which was higher at 20degreesC than at 4degreesC. Bacteriophage decay was shown to be log-linear from day 0, with T-90 values ranging from 9 (PhiX174, 20degreesC) to 55 days (PhiX174, 4degreesC). The MS2 phage had a significantly higher decay rate in tyndallized sediments (T-90 =17 days) than in original sediments (T-90 = 47 days) (P < 0.001), with temperature not shown to affect the decay rate. Spores of sulphite-reducing anaerobes were not significantly reduced during the study period (35 days). Campylobacter died-off rapidly or entered a viable but non-culturable state and subsequently results were not provided.Conclusions: Competition was the most important factor to suppress pathogenic bacterial growth in an eutrophic environment. When nutrient depleted conditions prevailed, temperature was more important and log-linear decay of microorganisms could be observed.Significance and Impact of the Study: These findings suggest that the normally occurring microbiota will suppress pathogenic bacterial growth in nutrient rich sediments. With lower nutrient status, temperature is the more important factor in reducing pathogens.

Keywords

bacteriophages; decay; greywater; pathogens; sediment

Published in

Letters in Applied Microbiology
2003, Volume: 36, number: 3, pages: 168-172
Publisher: BLACKWELL PUBLISHING LTD 9600 GARSINGTON RD, OXFORD OX4 2DG, OXON, ENGLAND

UKÄ Subject classification

Microbiology


Publication identifier

DOI: https://doi.org/10.1046/j.1472-765X.2003.01286.x

Permanent link to this page (URI)

https://res.slu.se/id/publ/38669