AUTORADIOGRAPHIC DETECTION OF RADIOACTIVE BACTERIA INTRODUCED INTO SEA WATER AND SEWAGE

Journal Article · Sun Sep 01 04:00:00 EDT 1963 · Journal of Hygiene (England)

DOI:https://doi.org/10.1017/S0022172400039589· OSTI ID:4107882

Berlin, M; Rylander, R

A new method, involving radioisotope labeling, is reported as a means of tracing the contamination of water by bacteria. Radioactive substances and dyes have also been used previously to study the spread of contamination, but because of rapid dilution, high levels of radioactivity are necessary to follow dispersion in large volumes of water. Bacteria which have been radioactively labeled can be used as tracer organisms if they can be detected by a method which avoids the necessity of culturing water samples, and if the method is sufficiently sensitive, the use of radioactive bacteria offers several advantages. In the method described, for use in studying the spread of bacteria in water, water samples were filtered through a Millipore filter and an autoradiogram of the filter was prepared in which the bacteria appeared as black spots. The accuracy and sensitivity of the method were estimated and a test made under field conditions. Strain B Escherichia coli were used, grown overnight at 37 deg C in medium containing 10 mC MgS/sup 35/O/sub 4/ per l. Autoradiographic determination of bacteria was made by diluting 1 ml from each water sample in 500 ml of 0.9% NaCl and filtering the solution through a Millipore filter (type HA, pore size 0.45 mu ). The filters were dried at 50 deg C for 20 min and applied to x-ray film for 10-day exposure. To evaluate the practicability of this autoradiographic method, a study was made of the spread of bacteria from the effluent of a household septic tank which discharged via a sewer into an inlet of the Baltic Sea near Stockholm. Autoradiograms were prepared from water samples obtained before and after radioactive bacteria were added to the sewer. The observed presence in the autoradiogams of images which resembled, but were not caused by radioactive bacteria, were one factor which limits the sensitivity of the method described. These images were found in equal numbers in autoradiograms of filters through which water without radioactive bacteria has been filtered. Thus, the backgound value must be determined in every experiment before the radioactive bacteria are added to the water. A larger number of bacteria were found in the autoradiograms compared to the number of colonies found on viable count. This may be due to the presence of aged bacteria which no longer give colonies on nutrient agar but still retain their activity. Apparently a thin layer of sludge does not absorb enough radiation from the bacteria to interfere with the autoradiographic results. Because the cells are retained on rather than in the filter, absorption of radiation by the filter is negligible. Hence, the method appears to be suitable for practical use. A small number of bacteria can be detected, and the sensitivity of the method increases if there is less sludge in the water. (BBB)

• Research Organization: Karolinska Inst., Stockholm
• Sponsoring Organization: USDOE
• NSA Number: NSA-18-011565
• OSTI ID: 4107882
• Journal Information: Journal of Hygiene (England), Journal Name: Journal of Hygiene (England) Vol. Vol: 61; ISSN JOHYA
• Country of Publication: Country unknown/Code not available
• Language: English

Related Subjects

ABSORPTION
BACTERIA
BIOLOGY AND MEDICINE
CONTAMINATION
DISPERSIONS
DYES
EFFICIENCY
ESCHERICHIA COLI
FILTERS
LABELLED COMPOUNDS
MAGNESIUM SULFATES
NUCLEAR EMULSIONS
RADIOAUTOGRAPHY
RADIOISOTOPES
SEA
SODIUM CHLORIDES
SOLUTIONS
SULFUR 35
TEMPERATURE
TRACER TECHNIQUES
USES
WATER
X RADIATION