Scholarly record

HALOBACTERIUM SALINARUM VIRUSES AND OPTIMIZATION OF VIRAL INDUCTION

Ivan Volokitin

Abstract

The study of halobacterial communities is a promising direction in applied and theoretical biotechnology. Researches, carried out in this field, open up new approaches in understanding the role of interspecies interactions between halobacterial cells in conditions of increased salinity. Viruses, as one of the major regulation factor, greatly affect the composition of communities. Every year the halovirus database is replenished with new representatives, but still much remains unknown about the life cycle of viruses, their biochemical composition, the mechanisms of interaction between the agent and the cell wall. To examine the impact of haloviruses and identify the morphological and biochemical composition of the agent, the study on the model cell culture was considered. Extreme halophilic archaebacteria Halobacterium salinarum was used as a host cells source. As a major member of many of the halobacterial communities, H. salinarum are the most studied and applied halophilic extremophiles in biotechnological researches. Pure viral samples were isolated from Alikes (Kos, Greece) and Elton (Russia) salt lakes. The process of viral infection was optimized. The viability of the virus depends largely on physicochemical factors such as temperature, pH, UV irradiation and cell density. Infected culture was cultivated in flasks and then plaque form units (PFU) were calculated. The process of viral induction mechanism was reproduced: physicochemical conditions were optimized and the most appropriate stage of host-cell growth was selected. It was found that the most suitable conditions for the haloviral infection close to the natural circs for halobacterial cells (mineral composition, temperature, pH, UV). Changing in NaCl concentration leads to a viral death, while changing in MgSO4, affecting on the strength of the cell wall, give no results. The induction mechanism requires higher temperature (T = 41 ? 45 В°C), pH 8.3 - 8.5, N (short-term UV irradiation) = 760 mW / m2. The cell density influence was studied on flasks and bioreactor. The maximum degree of the cell death is observed in the end of the exponential phase. Viral images were obtained and primary morphological characteristic was determined. Further, a biochemical analysis of capsid is planned. Also, the presented research should be transferred to the model halobacterial community to assess the impact of viruses in regulation mechanisms.

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