Nitrosylmyoglobin formation in meat by Lactobacillus fermentum AS1.1880 is due to its nitric oxide synthase activity

The objective of this study was to clarify whether formation of nitrosylmyoglobin (MbFe(II)NO) by Lactobacillus fermentum AS1.1880 in meat is due to nitric oxide synthase (NOS) activity. Confocal laser scanning microscopy exhibited strong green fluorescence in the L. fermentum sample treated with a nitric oxide (NO)-specific probe, directly indicating that NO was produced. Furthermore, determination of NOS activity based on the presence of NO metabolites indicated the existence of NOS in L.fermentum. A NOS inhibitor, N-G-nitro-L-arginine methyl ester, significantly inhibited the activity of NOS in L.fermentum (P < 0.05). Futhermore, NOS protein was detected in L.fermentum by Western blot analysis. L-arginine addition largely increased the NOS activity of L.fermentum (P < 0.05). In meat batters, the redness of a sample inoculated with L.fermentum was higher than that of the control and colour was significantly improved with the addition of L-arginine (P < 0.05), indicating that more MbFe(II)NO was formed.