Cloning and Analysis of the l-Lactate Utilization Genes from Streptococcus iniae

AUTOR(ES)

Gibello, A.

FONTE

American Society for Microbiology

RESUMO

The presence of lactate oxidase was examined in eight Streptococcus species and some related species of bacteria. A clone (pGR002) was isolated from a genomic library of Streptococcus iniae generated in Escherichia coli, containing a DNA fragment spanning two genes designated lctO and lctP. We show that these genes are likely to be involved in the l-lactic acid aerobic metabolism of this organism. This DNA fragment has been sequenced and characterized. A comparison of the deduced amino acid sequence of LctP protein demonstrated that the protein had significant homology with the l-lactate permeases of other bacteria. The amino acid sequence of the LctO protein of S. iniae also showed a strong homology to l-lactate oxidase from Aerococcus viridans and some NAD-independent lactate dehydrogenases, all belonging to the family of flavin mononucleotide-dependent α-hydroxyacid-oxidizing enzymes. Biochemical assays of the gene products confirm the identity of the genes from the isolated DNA fragment and reveal a possible role for the lactate oxidase from S. iniae. This lactate oxidase is discussed in relation to the growth of the organism in response to carbon source availability.

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