BACTERIAL DIGESTIVE ENZYME-ACTIVITY IN THE STOMACH AND HEPATOPANCREASOF MEGANYCTIPHANES-NORVEGICA (M SARS, 1987)

Northern krill, Meganyctiphaunes norvegica were maintained in antibiot ic-treated (''A''), and untreated (control, ''C'') aquaria. Each 24 h (for 72 h) numbers of saprophytic (Colony Forming Units, CFU), chitino lytic, and total bacteria (Acridine Orange Direct Count, AODC), were d etermined in the stomachs and hepatopancreata of animals. Parallely, t he activities of chitinase, N-acetyl-beta-D-glucosaminidase (NAGase), protease, cellulase and laminarinase were measured, and bacterial and endogenous chitinases compared by Fast Protein Liquid Chromatography ( FPLC). CFU in ''C'' group stomachs were stable, but varied widely in t he ''A'' group. AODC did not vary to any great extent. Hepatopancreas CFU decreased by four orders in the ''A'' compared to the ''C'' group. In ''C'' hepatopancreata, AODC were slighly higher than in ''A''. Num bers of chitinolytic bacteria fell steeply in the ''A'' group. Chitina se, NAGase, protease, and cellulase activities in the stomach were sig nificantly lower (5% level) after 24 h in ''A'' than in ''C''. Laminar inase activity was significantly reduced in both organs after 72 h. He patopancreas chitinase and protease activities showed significant redu ctions only after 24 h. FPLC elution profiles of NAGase from krill, an d bacteria grown on a medium semi-selective for chitinolytic bacteria differed. A number of bacterial chitinase peaks were absent in the ''A '' group. The API Zym system showed reduced proteolytic and lipase (C1 4) activity over 72 h. Endogenous bacteria are considered commensal wi th respect to the enzymes discussed.