Growth of the extremophilic Deinococcus geothermalis DSM 11302 using co-substrate fed-batch culture

Abstract

Deinococcus geothermalis metabolism has been scarcely studied to date, although new developments on its utilization for bioremediation have been carried out. So, large-scale production of this strain and a better understanding of its physiology are required. A fed-batch experiment was conducted to achieve a high cell density non-limiting culture of D. geothermalis DSM 11302. A co-substrate nutritional strategy using glucose and yeast extract was carried out in a 20-L bioreactor in order to maintain a non-limited growth at a maximal growth rate of 1 h(-1) at 45 °C. Substrate supplies were adjusted by monitoring online culture parameters and physiological data (dissolved oxygen, gas analyses, respiratory quotient, biomass concentration). The results showed that yeast extract could serve as both carbon and nitrogen sources, although glucose and ammonia were consumed too. Yeast extract carbon-specific uptake rate reached a value 4.5 times higher than glucose carbon-specific uptake rate. Cell concentration of 9.6 g L(-1) dry cell weight corresponding to 99 g of biomass was obtained using glucose and yeast extract as carbon and nitrogen sources.

Quantitative Characterization of the Growth of Deinococcus geothermalis DSM-11302: Effect of Inoculum Size, Growth Medium and Culture Conditions

“…Several published results have reported that Deinococcaceae are proteolytic microorganisms and prefer other carbon sources than glucose in yeast extract and tryptone, like amino acids [ 2 , 28 ]. With a D. geothermalis strain, the best growth performances described to date have been obtained using a glucose-yeast extract co-substrate fed-batch culture [ 15 ]. So, five solutions were supplemented to the basal defined medium: a solution containing yeast extract vitamins, a casamino acid vitamin-free solution providing all the essential amino acids except tryptophan, and three cellular extracts; the results are shown in Table 8 .…”

“…Only two works reported high cell density production of Deinococcaceae strains, e.g., Deinococcus radiodurans and Deinococcus geothermalis . The cultures were performed in a 20 L fermentor with a medium containing yeast extract [ 15 , 16 ]. Although previous works have shown that Deinococcaceae have complex nutritional requirements [ 2 , 13 , 17 , 18 ], no study has been reported yet on the influence of the inoculum preparation on their growth properties (growth rate, maximal biomass concentration, glucose uptake).…”