Early Response of Sulfolobus acidocaldarius to Nutrient Limitation

Abstract

In natural environments microorganisms encounter extreme changes in temperature, pH, osmolarities and nutrient availability. The stress response of many bacterial species has been described in detail, however, knowledge in Archaea is limited. Here, we describe the cellular response triggered by nutrient limitation in the thermoacidophilic crenarchaeon Sulfolobus acidocaldarius. We measured changes in gene transcription and protein abundance upon nutrient depletion up to 4 h after initiation of nutrient depletion. Transcript levels of 1118 of 2223 protein coding genes and abundance of approximately 500 proteins with functions in almost all cellular processes were affected by nutrient depletion. Our study reveals a significant rerouting of the metabolism with respect to degradation of internal as well as extracellular-bound organic carbon and degradation of proteins. Moreover, changes in membrane lipid composition were observed in order to access alternative sources of energy and to maintain pH homeostasis. At transcript level, the cellular response to nutrient depletion in S. acidocaldarius seems to be controlled by the general transcription factors TFB2 and TFEβ. In addition, ribosome biogenesis is reduced, while an increased protein degradation is accompanied with a loss of protein quality control. This study provides first insights into the early cellular response of Sulfolobus to organic carbon and organic nitrogen depletion.

The Cell Membrane of Sulfolobus spp.—Homeoviscous Adaption and Biotechnological Applications

“…Zhou et al conducted continuous cultivations and regulated the growth rate via the feed addition while a constant temperature, pH and aeration rate was given [78]. Slower growth rates increased the cyclization, which is in conformity with the experiments conducted with the nutrient depleted medium by Bischof et al [79] The RI changed from 2.0 in the highest applied growth rate of µ = 0.069 h −1 to 3.2 when a slow growth of µ = 0.01 h −1 was set. The amount of GDGT-4 to 6 increased with the decreasing growth rate.…”

“…Harvesting and subsequent transfer into nutrient rich and depleted medium was performed at an OD 600 of 0.4 to 0.5, which might suggest that, at this time point, the cells were still in the exponential phase and the previously described drop in average cyclization still took place. A slight decrease in the DEL amount upon nutrient depletion was observed, as shown in their Supplementary Material [79].…”

“…Recent studies by Jensen et al [42], Bischof et al [79], Zhou et al [78] and Quehenberger et al [43] confirm that growth phase/rate also have an effect on the lipid composition of Sulfolobales. Jensen et al observed that the lipid compositions of S. islandicus and S. tokodaii not only changed with the cultivation temperature, but also with the growth phase.…”

“…Temperature positive [42,46] impacted, but no distinct trend determined [42] impacted, but no distinct trend determined pH not investigated not investigated calditol important for acid resistance [39] Growth Rate Negative [43,78,79] negative [43] impacted, but no distinct trend determined [42] impacted, but no distinct trend determined [42,43] 3.1. Temperature Sulfolobus spp.…”

The influence of the specific growth rate on the lipid composition of Sulfolobus acidocaldarius

“…A third factor with supposedly high potential to impact the lipid composition is (3) the level of energy and nutrient supply of the culture. A study performed by Bischof et al (2019) showed that complete starvation of the uracil auxotrophic strain S. acidocaldarius MW001 resulted in a higher number of cyclopentane rings compared to nutrient rich conditions.…”