ABSTRACTThe metabolic cooperation in the ecosystem ofBacillus megateriumandKetogulonicigenium vulgarewas investigated by cultivating them spatially on a soft agar plate. We found thatB. megateriumswarmed in a direction along the trace ofK. vulgareon the agar plate. Metabolomics based on gas chromatography coupled with time-of-flight mass spectrometry (GC-TOF-MS) was employed to analyze the interaction mechanism between the two microorganisms. We found that the microorganisms interact by exchanging a number of metabolites. Both intracellular metabolism and cell-cell communication via metabolic cooperation were essential in determining the population dynamics of the ecosystem. The contents of amino acids and other nutritional compounds inK. vulgarewere rather low in comparison to those inB. megaterium, but the levels of these compounds in the medium surroundingK. vulgarewere fairly high, even higher than in fresh medium. Erythrose, erythritol, guanine, and inositol accumulated aroundB. megateriumwere consumed byK. vulgareupon its migration. The oxidization products ofK. vulgare, including 2-keto-gulonic acids (2KGA), were sharply increased. Upon coculturing ofB. megateriumandK. vulgare, 2,6-dipicolinic acid (the biomarker of sporulation ofB. megaterium), was remarkably increased compared with those in the monocultures. Therefore, the interactions betweenB. megateriumandK. vulgarewere a synergistic combination of mutualism and antagonism. This paper is the first to systematically identify a symbiotic interaction mechanism via metabolites in the ecosystem established by two isolated colonies ofB. megateriumandK. vulgare.
Enhanced 2-keto-l-gulonic acid production by a mixed culture of Ketogulonicigenium vulgare and Bacillus megaterium using three-stage temperature control strategy
