This content is not included in
your SAE MOBILUS subscription, or you are not logged in.
Survival of Pathogenic Bacteria Under Nutrient Starvation Conditions
Annotation ability available
Sector:
Language:
English
Abstract
The purpose of this research is to determine the survival of human pathogens within a water distribution system proposed for the orbiting space station. Initially we investigated the survival of opportunistic pathogenic microorganisms in water under nutrient limiting conditions. A strain of Pseudomonas aeruginosa and two strains of Staphylococcus aureus were grown to mid-log phase then transferred to a starvation regime of sterile deionized water. Cultures were incubated at 10°, 25° or 37° C and were sampled at 24 hr, 1 week, 4 weeks and 6 weeks. The viable cell density was determined by enumerating colony forming units and by directly counting cells stained with acridine orange. Neither of the Staphylococcus strains tested were detected after 1 week of starvation. Our data indicate that Pseudomonas aeruginosa can survive in deionized water at all three temperatures tested at levels exceeding 104 cells per ml. The bacterial surface characteristics associated with attachment under nutrient limiting conditions are currently being examined.
The formation of microbial biofilms in the pipes and filters of the water reclamation system (WRS) aboard the orbiting space station (OSS) poses a potential health risk. Reclamation of shower, laundering, and dish washing water will be necessary for long duration space flight. This waste water will be heavily contaminated with bacteria including opportunistic pathogens. Such a closed loop reclamation system will provide an ideal environment for the development of a biofilm, which is composed of bacterial cells in close association with extracellular polymers. Once a biofilm has formed within the piping and filtering systems of the WRS, an infectious reservoir of opportunistic pathogens can develop.
Our experience working with surface films of microorganisms has shown that colonization is extremely rapid, even when the inoculum is small. After initial colonization, build-up of an extensive biofilm occurs. Many opportunistic pathogens readily attach to surfaces and will survive and proliferate within films. The nature of biofilms is such that they resist physical cleaning techniques and penetration of biocides. They are therefore extremely difficult to eliminate and will continually be a source of potentially pathogenic microorganisms.
Biofilms have the potential not only to decrease the diffusion rate of biocides ILLEGIBLEbut ILLEGIBLEalso to react with chemical oxidants (e.g. iodine) intended to destroy living cells. The effective concentration of a biocide needed to remove possible pathogens will be dependent to some degree on the thickness of the biofilm. The removal of this organic layer on the surface would also eliminate the source of free-living (planktonic) cells that can slough off to reinoculate the water distribution system downstream (1).*
The unique nature of the WRS, based within the OSS where the human immune system will be compromised, necessitates extremely high sanitary standards. These standards are, however, currently unobtainable without the addition of chemicals at high concentration which themselves pose a serious health risk. In order to develop an effective method of water purification within the WRS that does not involve high levels of toxic chemicals, it is necessary to improve our understanding of basic mechanisms of initial attachment and subsequent film formation. This information will permit the development of non-toxic “biofilm inhibitors” working perhaps at the level of attachment prevention or “biofilm matrix” degradation.
The sequence of events that leads to the irreversible adhesion of bacteria to a surface is summarized in Table 1 (2). Important factors that contribute to the adhesion process include a) the characteristics of the substratum, b) the presence and composition of a molecular film on the substratum, and c) the physiological state of the bacterium. These different surface characteristics and the methods used to measure them have been discussed recently in detail (3,4,5).
Pseudomonas aeruginosa is a common bacterium capable of causing severe infections in compromised hosts. The irreversible attachment of P. aeruginosa to stainless steel (304) can occur within the first minute of exposure. Furthermore, pH, cation concentration and cell motility are important factors involved in the adhesion of this bacterium (6). P. aeruginosa can produce large amounts of exopolysaccharides as well as form biofilms on various surfaces (e.g. PVC, stainless steel, copper) (7,8,9). The exopolysaccharide material may help to irreversibly bind the bacteria to certain surfaces while also protecting this bacterium from biocides. P. aeruginosa has recently been reported to survive (i.e. 106 cell ml-1) for up to 15 months in an iodine “germicide” solution, a proposed disinfectant for the WRS (10).
Despite our knowledge of the the mechanisms of attachment of bacteria to surfaces, we know little about the role that nutrient limition has on initial adhesion and biofilm development. This paper describes an investigation on the survival of a specific opportunistic pathogen under starvation conditions at three different temperatures. The purpose of this study was to determine the survival of human pathogens and subsequent adsorbtion to the inner surfaces of the water distribution system on the orbiting space station.
Authors
- Michael Boyle - Division of Applied Sciences, Harvard University Cambridge, MA
- Tim Ford - Division of Applied Sciences, Harvard University Cambridge, MA
- Ralph Mitchell - Division of Applied Sciences, Harvard University Cambridge, MA
- James Maki - Division of Applied Sciences, Harvard University Cambridge, MA
Topic
Citation
Boyle, M., Ford, T., Mitchell, R., and Maki, J., "Survival of Pathogenic Bacteria Under Nutrient Starvation Conditions," SAE Technical Paper 901381, 1990, https://doi.org/10.4271/901381.Also In
References
- van der Wende, E. Characklis W.G. 1990 Biofilms in water distribution systems McFeters G.A. Drinking Water Microbiology Springer-Verlag New York
- Maki, J.S. Mitchell R. 1989 Bianchi M. et al
- Fletcher, M. Marshall K.C. 1982 Are solid surfaces of ecological significance to aquatic bacteria? Adv. Microb. Ecol. 6 199 236
- Rutter, P.R. Vincent B. 1984 Physicochemical interactions of the substratum, microorganisms, and the fluid phase 21 38 Marshall K.C. Microbial Adhesion and Aggregation Springer-Verlag Berlin
- Loeb, G. 1985 The properties of nonbiological surfaces and their characterization 111 129 Savage D.C. Fletcher M. Bacterial Adhesion Plenum Press New York
- Stanley, P.M. 1983 Factors affecting the irreversible attachment of Pseudomonas aeruginosa to stainless steel Can. J. Microbiol. 29 1493 1499
- Mian, F.A. Jarman T.R. Righelato R.C. 1978 Biosynthesis of exopolysaccharide by Pseudomonas aeruginosa J. Bacteriol 134 418 422
- Dunne, W.M. Buckmire F.L.A. 1985 Effects of divalent cations on the synthesis of alginic acid-like exopolysaccharide from mucoid Pseudomonas aeruginosa Microbios 43 193 216
- Anderson, R.L. Berkelman R.L. Mackel D.C. Davis B.J. Holland B.W. Martone W.J. 1984 Investigations into the survival of Pseudomonas aeruginosa in poloxamer-iodine Appl. Environ. Microbiol 47 757 762
- Anderson, R.l. Holland B.W. Carr J.K. Bond W.W. Favero M.S. 1990 Effect of disinfectants on pseudomonas colonized on the interior surface of PVC pipes Amer. Jour. Public Health 80 17 21
- Mitchell, R. Ford T.E. Stanley P.M. Keller J.D. Scwach T.S. 1987 Microbiological evaluation of NASA whole body shower biofilm 152
- Hobbie, J.E. Daley R.J. Jasper S. 1977 Use of nuclepore filters for counting bacteria by fluorescence microscopy Appl. Environ. Microbiol 33 1225 1228
- Conway, P.L. Maki J. Mitchell R. Kjelleberg S. 1986 Starvation of marine flounder, squid, and laboratory mice and its effect on the intestinal microbiota FEMS Microbiol. Ecol 38 187 195
- Little, B.J. Wagner P. Maki J.S. Walch M. Mitchell R. 1986 Factors influencing the adhesion of microorganisms to surfaces J.Adhesion 20 187 210
- Kjelleberg, S. Hermansson M. Marden P. Jones G.W. 1987 The transient phase between growth and nongrowth of heterotrophic bacteria, with emphasis on the marine environment Ann. Rev. Microbiol 42 25 49