Cultivating Limnospira fusiformis from Lake Solenoye, Omsk

Abstract

Global food shortages make it necessary to look for alternative renewable bioresources. In the south of Western Siberia, the filamentous cyanoprokaryote Limnospira fusiformis triggers seasonal algae bloom in hypergaline alkaline Lake Solenoye. The species has valuable nutritional properties, and its phytomass is a potential source of proteins and biologically active substances. The O9.13F strain of L. fusiformis has a good potential as a bioadditive in animal feeding. The article offers a technology for cultivating O9.13F of L. fusiformis, isolated from Lake Solenoye. The research objectives were to establish the optimal cultivation conditions, medium, and periodicity.
 The study featured strain O9.13F of filamentous cyanoprokaryote L. fusiformis. The micropipette method made it possible to isolate pure culture from water samples taken from Lake Solenoye, Omsk, Russia, at the end of algae bloom. The cultivation involved a UT-6070 climatic chamber under uniform illumination with light intensity 10–30 μmol photons/m2s and 12-h light-dark circle at 20 ± 2°C on various media: natural habitat – water from the Solenoye Lake; mineral medium – liquid Zarrouk’s medium; agarized Zarrouk’s medium; composite variants, where the ratio of mineral medium vs. water varied from 1:9 to 9:1.
 Lake water inhibited the culture growth: the trichomes died and sank on day 10–15. Zarrouk’s agarized medium stopped the culture growth as early as on day 2. The most intensive growth and development of the culture was observed in the samples with Zarrouk’s mineral liquid medium and a composite mix of Zarrouk’s medium and sterilized water at a ratio of 5:5. Without stirring, full-fledged trichomes had no time to develop, and the increase in phytomass volume slowed down. O9.13F showed the highest rate of phytomass growth at a cultivation temperature of 20 ± 2°C and a light intensity of 10–30 μmol photons/m2s. The recommended light-dark circle was12:12 h. Zarrouk’s mineral liquid medium and a composite medium of Zarrouk’s medium and sterilized water proved to be optimal in a UT-6070 environmental chamber. Europolitext KV-06 or mechanical mixing could prevent sedimentation of phosphates after 20 days of cultivation. The optimal recultivation frequency was once every 5–7 days. 
 The new cultivation technology made it possible to obtain a significant volume of L. fusiformis phytomass in a short time and with low financial expenses.