Abstract:[Objective] To study the effects and possible mechanism of exogenous addition of different amino acids and compatible solutes on the growth of Corynebacterium glutamicum under high sugar stress. [Methods] Various amino acids and compatible solutes were individually added into the indicated medium supplemented with high glucose or sucrose, and their potential effects on the growth of C. glutamicum were examined. The influences of exogenous arginine on the transcription levels of some key enzymes involved in sugar transport and metabolic pathways, as well as the fermentative production of amino acids under high glucose stress, were also explored. Moreover, the potential roles of basic amino acids in protecting against high glucose challenge were also analyzed in other Corynebacterium species. [Results] Under high glucose stress, the biomass of C. glutamicum increased by 54.7%, 50.0% and 37.6% by addition of exogenous lysine, arginine and histidine, respectively, while the addition of exogenous proline or ectoine increased the biomass of C. glutamicum more than 20% under high sucrose stress. Further studies revealed that exogenous arginine resulted in a nearly 2.5-fold higher glucose utilization rate, and the amount of L-glutamic acid by fermentation increased by 127.5% in the presence of arginine under high glucose stress. Additionally, the osmoprotective effects of basic amino acids in response to high glucose stress were also observed in other four Corynebacterium species. [Conclusion] Arginine plays an osmoprotective role for C. glutamicum under high glucose stress, which may be attributed to its ability to promote glucose transport and metabolism. Meanwhile, the osmoprotective effects of basic amino acids in response to high glucose were shown to be applicable to other Corynebacterium species.
