PARTIAL CHARACTERIZATION OF AN RPOD-LIKE GENE OF LACTOCCOCUS-LACTIS SUBSP-LACTIS ML3 WITH A POLYMERASE CHAIN REACTION-BASED APPROACH

With degenerated oligonucleotide primers for conserved regions of bact erial sigma factor proteins, a 117-bp internal DNA fragment of an rpoD -like gene of Lactoccocus lactis subsp. lactis ML3 was amplified by th e polymerase chain reaction (PCR). The DNA sequence of this PCR produc t was determined by cycle sequencing, and the deduced amino acid seque nce of this internal fragment showed an extensive homology with the kn own sigma factor sequences from six other microorganisms and present a 13-amino acid region corresponding to the typical ''RpoD box'' of pri mary sigma factors. This PCR product was used as a probe to specifical ly detect sigma homologs in Pediococcus acidilactici, Leuconostoc lact is, Lactobacillus helveticus, Lactobacillus acidophilus, Enterococcus faecalis, Streptococcus thermophilus, and Lactococcus lactis subsp. cr emoris. These data are consistent with the existence of a high similar ity between the primary sigma factors from diverse Gram-positive micro organisms.