Investigation of Factors Affecting Aerobic and Respiratory Growth in the Oxygen-Tolerant Strain Lactobacillus casei N87

Abstract

Aerobic and respiratory cultivations provide benefits for some lactic acid bacteria (LAB). Growth, metabolites, enzymatic activities (lactate dehydrogenase; pyruvate and NADH oxidases, NADH peroxidase; catalase), antioxidant capability and stress tolerance of Lactobacillus casei N87 were evaluated in anaerobic, aerobic and respiratory (aerobiosis with heme and menaquinone supplementation) batch cultivations with different dissolved oxygen (DO) concentrations. The expression of pox (pyruvate oxidase) and cydABCD operon (cytochrome bd oxidase complex) was quantified by quantitative Real Time polymerase chain reaction. Respiration increased biomass production compared to anaerobiosis and unsupplemented aerobiosis, and altered the central metabolism rerouting pyruvate away from lactate accumulation. All enzymatic activities, except lactate dehydrogenase, were higher in respiratory cultures, while unsupplemented aerobiosis with 60% of DO promoted H2O2 and free radical accumulation. Respiration improved the survival to oxidative and freeze-drying stresses, while significant numbers of dead, damaged and viable but not cultivable cells were found in unsupplemented aerobic cultures (60% DO). Analysis of gene expression suggested that the activation of aerobic and respiratory pathways occurred during the exponential growth phase, and that O2 and hemin induced, respectively, the transcription of pox and cydABCD genes. Respiratory cultivation might be a natural strategy to improve functional and technological properties of L. casei.

Tween 80 and respiratory growth affect metabolite production and membrane fatty acids inLactobacillus caseiN87

“…More recently, Ianniello et al . () have verified that in Lact. casei N87 the expression of pox gene and the enzymatic activity of POX were positively regulated by respirative condition.…”

“…, ; Ianniello et al . ), to our knowledge the relationship between respiration and cell membrane composition has never been considered. Besides, only a few studies (Ricciardi et al .…”

Aerobic metabolism in the genusLactobacillus: impact on stress response and potential applications in the food industry

“…; Ianniello et al . ). FBP may repress the expression of ack gene via CcpA repression (Lopez de Felipe and Gaudu ).…”

“…; Ianniello et al . , ). Anaerobic conditions repress pox transcription, while oxygen supplementation favours both gene expression and enzymatic activity (Lorquet et al .…”

“…; Ianniello et al . , ). On the other hand, high levels of H 2 O 2 and dissolved oxygen (>30% DO) may impair POX functionally and gene expression (Quatravaux et al .…”