Bacillary spores disinfection
New Approaches to Bacillary Spores Desinfection with the Help of Integrated Influence with Minimal-Optimal Radiation Doses
Tech Area / Field
- BIO-SFS/Biosafety and BioSecurity/Biotechnology
8 Project completed
Senior Project Manager
Melnikov V G
VNIIEF, Russia, N. Novgorod reg., Sarov
- Nizhni Novgorod State University name after N.I. Lobachevsky, Russia, N. Novgorod reg., N. Novgorod
- Brown University, USA, RI, Providence
Project summaryThe suggested project will be carried out by specialists in the field of microbiology (NNSU, RFNC-VNIIEF) and in the field of physics, especially in the area of physics of radiation influence (RFNC-VNIIEF).
The study of different aspects of resistance and other properties of gram-positive spore-forming aerobes/ facultative anaerobes seems to be really topical, especially in connection with the use of spore-forming bacteria for bacteriological sabotage (the example is the terrorist acts in the USA when anthrax spores (Bacillus anthracis) were used). The choice of the germ was conditioned by extremely high contagious ability and environmental survivability of the pathogen spores. As a result the spores are likely to get into the environment and contaminate it. Thus, the urgent problem of sanitation of contaminated objects arises.
It seems that the most effective way of combating pathogen spores, which have got into the environment where there is risk of contaminating people, is not their direct destruction, but their activation and vegetation stimulation, and then their destruction by more mild actions than the ones that would be required for destruction of resting spores.
One of the features of the suggested research is the study of the properties of saprophytic representatives of the Bacillaceae family, which are similar in their phenotype to B. anthracis, and not the anthrax pathogen itself. The results obtained in the experiments with saprophytic bacilli can be extrapolated to other kindred microorganisms including anthrax pathogen. Thus it is possible to obtain practical results without conducting expensive experiments (which in addition are connected with certain risk) in laboratories that have the authorization to work with quarantine infection pathogens.
The data received in the course of the suggested research can be used for development of sanitation techniques of enclosed spaces, which might have been contaminated with pathogen spores, and possibly for mail disinfection. The research may also be of interest in connection with the development of sanitation techniques of hospital premises that have been contaminated with spore-forming bacteria strains that might be the cause of intrahospital infection [10; 17; 12; 16].
The high survivability of endospores in the environment, specifically in soils, on top of different surfaces, in dust, in the air is well known as well as their ability to produce vegetative cells after a long period of being in anabiotic state. Bacilli endospores possess a very high resistance ability to various extreme influences: chemo- and thermoresistance [7; 17; 16; 2], resistance to lengthy desiccation, to high ionizing radiation doses , ultraviolet radiation , ultrasound and other influences [7; 13]. Thus, if we look at radiation impact that is considered a rather promising sanitation means, its absorbed dose index will be as high as ~ 10 gray.
Endospore resistance is genetically conditioned and determined by conformational alterations of all the bacterial cellular structures including the components of the cellular walls transforming into numerous spore coats.
Vegetative cells, when they are in metabolically active proliferating state, are vulnerable as far as the above-mentioned factors are concerned . For example, under radiation influence they become vulnerable at absorbed dose of ~102 gray. Transfer of spores into vegetative state allows to reduce the impact force of the aggressive factor and the duration of the treatment, and also to apply “milder” bactericidal factors. Germination of endospores occurs in living beings and in the environment under the change of some abiotic factors. Germination of endospores is facilitated by the increase in humidity and temperature, by the treatment with amino acids, sugar, surface-active materials (applicable in vitro), and also, apparently, by small radiation doses influence, which stimulates metabolism. The stimulating influence of radiation on microorganisms, when absorbed doses are comparatively small, is mentioned by a number of researchers [3; 7; 11; 14; 15].
In this connection the use of complex influence of a number of physical factors and radiation at certain absorbed doses as an effective means of initiation of spore germination is considered to be of great interest. Namely the complexity of the influence is considered to be new and promising as an effective way of initiation of endospore germination.
Research in this field will allow us to determine the optimal-minimal radiation doses, which are necessary for endospore germination, and also the extent to which they become vulnerable in germination state and corresponding dose sizes.
The research of the radiation influence will be conducted on a commercial X-ray unit, which will be used as an irradiator. Prepared biological objects will be exposed to X-radiation under conditions, which ensure the necessary radiation doses. For the research of biological objects at the irradiator VNIIEF specialist will develop a chamber possessing the necessary characteristics.
Also for research purposes a project for the premises rebuilding will be developed and in correspondence with it the necessary works will be carried out. This reconstruction will allow creating a workroom, which satisfies the safety requirements for conducting research with microorganisms. Both the project and the reconstructed workrooms will undergo all the necessary examinations by experts. The reconstruction works will be carried out against subcontract by RFNC VNIIEF department number 0430.
Research purpose: to develop a biological model and to study the gears of complex influence of physical factors and radiation at comparatively small absorbed doses in order to use the obtained results for development of techniques of sanitation of an environment contaminated with spores and vegetative cells of spore-forming bacteria.
Tasks: 1. Development of a biosystem for the study of complex influence of radiation on microorganisms under comparatively small absorbed doses and at additional physical factors (temperature, humidity).
2. Determination of the minimal-optimal radiation doses initiating spore germination, and comparatively higher radiation influences at which vegetative cells become vulnerable together with other ambient factors (temperature, humidity).
3. Study of different variants of development of spore germination under above stated influences.
4. Detection of specific character of complex radiation influences with particular absorbed doses and other factors on different strains of spore-forming and non-spore-forming bacteria (check variant).
5. Development of a chamber for the study of biological objects on the irradiator.
6. Ensuring certain necessary conditions of radiation influence together with other physical factors (temperature, humidity) when conducting research of biological objects.
Expected results: 1. A biosystem (spores + vegetative cells + gram-negative bacteria) will be developed to be used as a model for determination of radiation doses together with other physical factors for initiation of spore germination.
2. Radiation doses and operating conditions of other factors, which are optimal for spore modification and effective prevention and prophylaxis of some infections caused by spore-forming bacteria and, in particular, by bacteria similar in their phenotype to anthrax pathogen, will be determined.
3. Variants of different spore germination development under complex influence of radiation and other physical factors will be selected.
4. The specificity of the complex influence of radiation and other physical factors on different spore-forming and non-spore-forming bacteria strains will be shown.
Supposed duration of the project is 2 years.
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