Conservation techniques for promising bacteria in the oil industry to preserve biological properties

Background: The conservation of valuable bacterial strains is crucial for various scientific, industrial, and environmental applications. Microorganisms with oil-emulsifying and oil-displacing properties are potentially significant for biotechnologies applied in the oil industry, particularly in such areas as bioremediation and tertiary enhanced oil recovery. To supply enterprises with pure cultures of microorganisms, they should be constantly maintained in the collection conditions in an active state while monitoring the preservation of their biotechnological properties. Therefore, keeping microorganism strains in working conditions and preserving their valuable properties are important for almost any work with microorganisms, ranging from primary research to their use in the production of various biopreparations.

Aim: The article focuses on studying a method for preserving bacteria that are useful in the oil industry. This method involves modifying the technique of microencapsulating microorganism cells in alginate gel by adding glycerin, which is used as an agent with biostatic action.

Materials and methods: The subject of research are eight hydrocarbon-oxidizing cultures of microorganisms that were sourced from the Department of Biotechnology of the al-Farabi Kazakh National University. Of these, four cultures were spore-bearing, while the other four were non-spore-bearing. The research employed microbiological methods of cultivation and storage of microorganisms in both solid and liquid media under aerobic conditions. In addition, Cooper's method was used to determine oil emulsification index and statistical methods for data analysis.

Results: It has been found that adding glycerin (15% vol.) as a biostatic to the gel-forming matrix of sodium alginate can ensure long-term (up to 6 months) cell viability for the studied bacteria in the range of 88-96% while maintaining functionality of immobilized cells. The values of the bacteria’s oil emulsification remained at the pre-conservation levels, whereas traditional storage methods result in a lower number of viable cells after six months. It should be noted that after six months of being stored in encapsulated form with glycerin, the viability of non-sporе-forming Pseudomonas cultures is lower (88-91%) than spore-forming Bacillus (95-98%). This correlation is also is observed for traditional methods.

Conclusion: The modern method of preserving bacteria allows for their long-term storage while maintaining functionality and viability.