Isolation and Characterization of an L-Amino Acid Oxidase-Producing Marine Bacterium

One marine bacterial strain, R3, has been newly isolated from the intertidal zone of Dinghai sea area. Measurements of a-keto acids and H2O2existing in fermentation supernatant were carried out to show that R3 can produce L-amino acid oxidase (LAAO) with a broad substrate specificity. Physiological and biochemical analysis showed that it can grow great at the conditions with sodium chloride concentration of 1.5%-3%, temperature of 15?C -35?C and pH of 6-7. In addition, molecular identification of 16S rDNA was performed to show that R3 was proximal toPseudoalteromonasspp. with the highest identity of 98.5% toPseudoalteromonasrubra. Therefore, it was designated asPseudoalteromonassp. R3. Further studies are required to arrive at a better understanding of this LAAO and secure an application.

革兰氏阴性菌中β-内酰胺酶诱导表达调控机制研究进展

β-内酰胺类抗生素是应用最广的一类抗菌药物。β-内酰胺酶能将β-内酰胺类抗生素水解,其诱导表达是革兰氏阴性菌对该类抗生素产生耐药性的最主要原因。文中重点综述了革兰氏阴性菌中β-内酰胺酶诱导表达的两种调控机制。在经典的ampR-ampC调控系统中,β-内酰胺酶的诱导表达与肽聚糖循环密切相关,并且LysR型转录因子AmpR发挥核心的调控作用。近年来发现β-内酰胺类抗生素能激活双组分系统,从而诱导β-内酰胺酶的表达。最后,讨论了革兰氏阴性菌中β-内酰胺类耐药今后的研究方向。