Reactive Oxygen Species-Mediated Cellular Stress Response and Lipid Accumulation in Oleaginous Microorganisms: The State of the Art and Future Perspectives

Abstract

Microbial oils, which are mainly extracted from yeasts, molds, and algae, have been of considerable interest as food additives and biofuel resources due to their high lipid content. While these oleaginous microorganisms generally produce only small amounts of lipids under optimal growth conditions, their lipid accumulation machinery can be induced by environmental stresses, such as nutrient limitation and an inhospitable physical environmental. As common second messengers of many stress factors, reactive oxygen species (ROS) may act as a regulator of cellular responses to extracellular environmental signaling. Furthermore, increasing evidence indicates that ROS may act as a mediator of lipid accumulation, which is associated with dramatic changes in the transcriptome, proteome, and metabolome. However, the specific mechanisms of ROS involvement in the crosstalk between extracellular stress signaling and intracellular lipid synthesis require further investigation. Here, we summarize current knowledge on stress-induced lipid biosynthesis and the putative role of ROS in the control of lipid accumulation in oleaginous microorganisms. Understanding such links may provide guidance for the development of stress-based strategies to enhance microbial lipid production.

Xylose Metabolism and the Effect of Oxidative Stress on Lipid and Carotenoid Production in Rhodotorula toruloides: Insights for Future Biorefinery

“…The highest reported lipid production in R. toruloides is 0.675 g/gDCW (Li et al, 2007) using a rich medium with glucose as a carbon source. The review by Shi et al (2017) reports that different authors found evidence for ROS stress enhancing the formation of lipid droplets as an important signalling molecule in response to nitrogen starvation in oleaginous microorganisms. Cells under oxidative stress might possess an even greater supply of NADPH by channelling sugar catabolism to PPP to stabilise the redox balance and ROS clearance (Kuehne et al, 2015).…”

“…Catalase (CAT, RHTO_01370), which breaks down hydrogen peroxide in the peroxisomal matrix, was the most upregulated protein with a 6-fold increase under nitrogen limitation. Recent reports in oleaginous microorganisms showed that ROS is an important signalling molecules in response to various stresses (Shi et al, 2017). Nitrogen depletion is an example of such stress, leading to the accumulation of ROS Fan et al, 2014;Chokshi et al, 2017) and higher activities of catalase and other antioxidant enzymes, suggesting that lipid accumulation under nitrogen depletion is mediated by oxidative stress (Yilancioglu et al, 2014).…”

Temporal and metabolic overlap between lipid accumulation and programmed cell death due to nitrogen starvation in the unicellular chlorophyte Chlamydomonas reinhardtii

“…In other words, some cells actively die via PCD under these conditions. Manipulating stress-based strategies have been proposed as a way of enhancing microbial lipid production (Shi et al 2017). Manipulating the PCD process, for example, may represent an unexplored route towards increased lipid productivity.…”

“…The reason for the lipid biosynthesis-PCD overlap was not examined here. One aspect may be the cross-talk involving secondary messengers like reactive oxygen species, which are implicated in numerous stress-related responses (Goncalves et al 2016;Shi et al 2017).…”

Effects of dietary Antrodia cinnamomea fermented product supplementation on metabolism pathways of antioxidant, inflammatory, and lipid metabolism pathways-a potential crosstalk

“…Since nutrition is one of the most pertinent external factors in the prevention of diseases development, and the restricted ability of adaptive systems in animals to conquer oxidative stress, dietary supplementation with materials possessing antioxidant capacity become a decent candidate for external help in boosting endogenous defense mechanisms by influencing the redox sensitive molecules and thus identifying an important level of gene-nutrition interaction [6]. Several studies have demonstrated that as being secondary messengers to influence gene expression, ROS signaling route could be affected directly or indirectly by molecules attending lipid metabolism [7]. Moreover, oxidative stress induced by ROS accumulation is also considered to impair the optimal functioning of the immune system [8], showing the importance to target molecules involved in these signal transduction network.…”