COMPARISON OF PHYSIOLOGICAL AND BIOCHEMICAL CHARACTERISTICS OF 3 CHLORELLA STRAINS FOLLOWING LONG-TERM MAINTENANCE IN DIFFERENT COLLECTIONSUNDER DIVERSE CONDITIONS

The aftereffects of long-term maintenance (over 20 years) were compare d using three chlorella strains (mesophilic strain Chlorella pyrenoido sa A-82 and thermophilic strains Chlorella pyrenoidosa Tx 7-11-05 and Chlorella vulgaris LARG-1) from the collections of the Institute of Pl ant Physiology, Russian Academy of Sciences, Moscow (IPPAS) and of the Department of Microbiology, Moscow State University (DMMSU). After ma intenance in different collections, the strains differed in their viab ility (the proportion of alive cells on agar slants), as well as in gr owth rate; the number and size of cells; photosynthetic productivity ( expressed as biomass accumulation); the content of protein, carbohydra tes and chlorophyll when cells were brought to conditions providing fo r an intensive autotrophic growth. We conclude that a reduced-temperat ure regime is favorable for the maintenance of all strains in collecti ons. The temperature of 5-10 degrees C is accepted in DMMSU, and 10-12 degrees C is a preferred range in IPPAS collection. Maintenance under low-intensity light (2.2-2.5 W/m(2), the usual condition for the IPPA S collection) is found to suit mostly thermophilic strains. For mesoph ilic C. pyrenoidosa A-82 culture, maintenance in darkness, accepted in the DMMSU collection, seems to be favorable. The physiological specif icity of cultures (meso- and thermophilic strains) and selective press ure of the external condition complex maintained during pregrowing and maintenance periods, are apparent reasons for the diversity in strain response to maintenance conditions. The possibility of comparing the effect of maintenance conditions on unicellular algae, in particular c hlorella, in short-term experiments is considered. It is indicated by the results that scientific publications should, in addition to the sp ecies name, also identify the name or acronym of the collection and th e strain index accepted in a particular collection from which this str ain was directly obtained.