Two proteinases (I and II) from a marine luminous bacterium, FLN-108, were purified to homogeneity. The molecular weights ofproteinases I and II were estimated to be 49,000 and 46,000, comprising a dimer of 23,000 molecular weight subunits, respectively. These enzymes were most active at from pH 8.0 to pH 9.0 and 50°C, and stable below 45°C. These enzyme activities were inhibited by EDTAand orthophenanthrolin.Phosphoramidon inhibited the activity of proteinase II, but not that ofproteinase I. Metal ions such as Cu2+, Hg2+, and Ni2+ strongly inhibited these activities. These results indicate that the proteinases I and II are metal-chelater-sensitive, alkaline proteinases.Wehave reported the existence of proteolytic, marine luminous bacteria, and described the purification and some properties of these enzymes from the culture supernatants of Vibrio splendidus FLE-2 and Vibrio harveyi FLA-1 1 strains.1>2) Since the proteinase activity in the culture supernatant with BGPY (basal glycerol peptone yeast extract) medium,1) which is a nutritionally complete broth, was very low, it was examined whether the enzyme activity from other Vibrio harveyi strains is also lower than that with BC(basal casein) medium,2) which lacks carbon and energy sources other than the casein. We found that several strains, which were newly isolated and identified as Vibrio harveyi, could have high proteinase activity.In the BGPY medium, the proteinase activity of the culture supernatant of one of these strains, FLN-108, was 15-fold higher than that of V. harveyi FLA-ll, and this strain produced two proteinases, which had different electrophoretic mobilities.In this paper, we describe the identification of the proteolytic, marine luminous bacterium, FLN-108, which was isolated as one of one 3009 hundred and forty-one luminous strains from surface coastal water at Okinawa, Japan, and the purification and someproperties of these two proteinases from this luminous strain.
MATERIALS AND METHODSIsolation and identification of the organisms.
