AUTHOR=Davis Richard W. , Muse Charlotte G. , Eggleston Heather , Hill Micaila , Panizzi Peter 

TITLE=Sugar Shock: Probing Streptococcus pyogenes Metabolism Through Bioluminescence Imaging

JOURNAL=Frontiers in Microbiology

VOLUME=13

YEAR=2022

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2022.864014

DOI=10.3389/fmicb.2022.864014

ISSN=1664-302X

ABSTRACT=<p><italic>Streptococcus pyogenes</italic> (<italic>S. pyogenes</italic>) can thrive in its host during an infection, and, as a result, it must be able to respond to external stimuli and available carbon sources. The preclinical use of engineered pathogens capable of constitutive light production may provide real-time information on microbial-specific metabolic processes. In this study, we mapped the central metabolism of a <italic>luxABCDE</italic>-modified <italic>S. pyogenes</italic> Xen20 (<italic>Strep</italic>. Xen20) to its <italic>de novo</italic> synthesis of luciferase substrates as assessed by the rate of light production in response to different environmental triggers. Previous characterization predicted that the <italic>lux</italic> operon was under the myo-inositol <italic>iolE</italic> promotor. In this study, we revealed that supplementation with myo-inositol generated increased <italic>Strep.</italic> Xen20 luminescence. Surprisingly, when supplemented with infection-relevant carbon sources, such as glucose or glycine, light production was diminished. This was presumably due to the scavenging of pyruvate by <italic>L</italic>-lactate dehydrogenase (LDH). Inhibition of LDH by its inhibitor, oxamate, partially restored luminescent signal in the presence of glucose, presumably by allowing the resulting pyruvate to proceed to acetyl-coenzyme A (CoA). This phenomenon appeared specific to the lactic acid bacterial metabolism as glucose or glycine did not reduce signal in an analogous <italic>luxABCDE</italic>-modified Gram-positive pathogen, <italic>Staph</italic>. Xen29. The <italic>Strep.</italic> Xen20 cells produced light in a concentration-dependent manner, inversely related to the amount of glucose present. Taken together, our measures of microbial response could provide new information regarding the responsiveness of <italic>S. pyogenes</italic> metabolism to acute changes in its local environments and cellular health.</p>