Effect of visible light on progressive dormancy of Escherichia coli cells during the survival process in natural fresh water
Some effects of visible light on the survival of Escherichia coli in waters of the Butron river were studied by comparing illuminated and nonilluminated systems. The following count methods were used: CFU on a selective medium (eosin-methylene blue agar), CFU on a medium of recuperation (Trypticase soy agar with yeast extract and glucose), number of metabolically active cells by reduction of 2-(p-iodophenyl)-3-(p-nitrophenyl)-5-phenyl tetrazolium chloride (INT) to INT-formazan, and total number of E. coli cells as determined by the acridine orange direct-count method. In the illuminated systems, decreases in CFU of E. coli and in the number of metabolically active cells were observed. However, no decline of the total number of E. coli cells was observed. By count methods, different stages of progressive dormancy of E. coli cells were determined to exist in illuminated systems. Culturable and recoverable cells were defined as viable cells, and metabolically active cells and morphologically intact cells were defined as somnicells. Indirect activity measurements were also done by using (14C)glucose. In illuminated systems, a decrease of glucose uptake by E. coli cells was observed throughout the experiments. The assimilated fraction of (14C)glucose decreased faster than the respired fraction in illuminated systems. The percentage of respired (14C)glucose (14CO2 production) with respect to the total glucose uptake increased throughout the experiments, and the percentage of assimilated glucose decreased. Therefore, the visible light was also responsible for an additional inhibition of biosynthetic processes.
- Research Organization:
- Universidad del Pais Vasco, Bilbao (Spain)
- OSTI ID:
- 6154238
- Journal Information:
- Appl. Environ. Microbiol.; (United States), Vol. 55:1
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ESCHERICHIA COLI
SURVIVAL TIME
GLUCOSE
UPTAKE
VISIBLE RADIATION
BIOLOGICAL EFFECTS
ACRIDINE ORANGE
CARBON 14 COMPOUNDS
FRESH WATER
METABOLISM
TRACER TECHNIQUES
VIABILITY
ACRIDINES
ALDEHYDES
AMINES
AROMATICS
AZAARENES
AZINES
BACTERIA
CARBOHYDRATES
DYES
ELECTROMAGNETIC RADIATION
HETEROCYCLIC COMPOUNDS
HEXOSES
HYDROGEN COMPOUNDS
ISOTOPE APPLICATIONS
LABELLED COMPOUNDS
MICROORGANISMS
MONOSACCHARIDES
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
OXYGEN COMPOUNDS
PYRIDINES
RADIATIONS
SACCHARIDES
WATER
550501* - Metabolism- Tracer Techniques