Experimental and statistical analysis of nutritional requirements for the growth of the extremophile Deinococcus geothermalis DSM 11300

Abstract

Few studies concerning the nutritional requirements of Deinococcus geothermalis DSM 11300 have been conducted to date. Three defined media compositions have been published for the growth of this strain but they were found to be inadequate to achieve growth without limitation. Furthermore, growth curves, biomass concentration and growth rates were generally not available. Analysis in Principal Components was used in this work to compare and consequently to highlight the main compounds which differ between published chemically defined media. When available, biomass concentration, and/or growth rate were superimposed to the PCA analysis. The formulations of the media were collected from existing literature; media compositions designed for the growth of several strains of Deinococcaceae or Micrococcaceae were included. The results showed that a defined medium adapted from Holland et al. (Appl Microbiol Biotechnol 72:1074-1082, 2006) was the best basal medium and was chosen for further studies. A growth rate of 0.03 h(-1) and a final OD600nm of 0.55 were obtained, but the growth was linear. Then, the effects of several medium components on oxygen uptake and biomass production by Deinococcus geothermalis DSM 11300 were studied using a respirometry-based method, to search for the nutritional limitation. The results revealed that the whole yeast extract in the medium with glucose is necessary to obtain a non-limiting growth of Deinococcus geothermalis DSM 11300 at a maximum growth rate of 0.64 h(-1) at 45 °C.

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

“…Few hypotheses could explain the positive effect of yeast extract on the growth: yeast extract brings constitutive elements to the cells, it could provide growth factors like vitamins or enzyme cofactors and it could have a catalytic effect too. Even if data in the literature have highlighted a significant role of Mn and Mg for the growth of D. radiodurans [ 16 , 17 , 26 ], a trace element supplemented by yeast extract, our experiments did not confirm these observations for D. geothermalis [ 18 ]. This is not surprising since the mesophilic and the thermophilic strains are described to exhibit different metabolic capacities.…”

“…So, sequenced yeast extract supplies had no impact on final biomass concentration and number of generation but significant impact on the kinetics; yeast extract brings both constitutive and catalytic elements. Further analysis of the nutritional requirements of Deinococcus geothermalis have been performed: a respirometry-based method has been developed to study the major growth supporting components, and the results have revealed that the whole yeast extract in the medium is essential to obtain a non-limiting growth [ 18 ].…”

“…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). Inoculum preparation, including preservation method, revivification step and inoculum stages, is an essential element for the quality of the microbial culture and for bioprocess performances [ 19 ].…”