Search

A small rod, capable of formine crater-like plaques on lawns of Vibrio parahaemolyticus, was isolated from a marine environment. The isolate was a gram-negative straight rod with round ends and was small in size, equal to that of halophilic Bdellovibrio strain 5501. The isolate appeared to have close taxonomic relationships to Cytophaga, since this bacterium moved slowly in a gliding manner on a solid agar surface, hydrolyzed agar and starch, contained yellow pigment and was halophilic. The isolate was able to grow not only under host-dependent but also under host-independent conditions when low nutrient media were used for cultivation, and its bacteriolytic mode was different from that of Bdellovibrio, an endoparasite. The isolate was halophilic and required Mg++ and Ca++ in addition to 3% saline for growth. The isolate showed a broad host rnage when tested for plaque-forming activity on gram-negative bacteria but not on the gram-positive bacteria tested so far.

A simple method employing aminoglycoside-inactivating enzymes from Escherichia coil for identification of aminoglycosides (AGs) such as dihydrostreptomycin (DHSM), kanamycin (KM) and fradiomycin (FRM) in food was developed.The crude enzyme (S105) fraction was prepared by ultrasonic treatment of cells of drug-resistant E. coil, followed by centrifugation at 105, 000×g. DHSM was inactivated by the S105 fraction of SM-resistant E. coli in the presence of both adenosine triphosphate (ATP) and Mg2+, KM and FRM were also inactivated by the S105 fraction of KM-resistant E. coli in the presence of both ATP and Mg2+ Discrimination of KM from FRM was done by the inactivation of the former by commercial kanamycin-6′-acetyltransferase (AAC(6′)-1) in the presence of ATP, Mg2+ and acetyl CoA. KM was inactivated by the action of AAC(6′)-1, while FRM was not.Treatment of serum and kidney samples of rats, which had been intramuscularly injected with DHSM and KM and FRM, with these S105 fractions and AAC(6′)-1 resulted in the loss of the respective antimicrobial activities.When this method was applied to 4 bovine kidney samples in which AGs had been detected by the ordinary method, the AGs were identified as DHSM in two samples and KM in two other samples.This method is useful for identification of DHSM, KM and FRM in AGs-contaminated samples.