Microbial succession and intestinal enzyme activities in the developing rat

Abstract

The succession of gut bacteria and selected intestinal enzyme activities in developing 7-35-d-old rats was studied. Aerobes and anaerobes were identified as members of four broad major bacterial groups, i.e. Gram-positive rods, Gram-positive cocci, Gram-negative rods and obligate anaerobes. The enzyme activities of nitro and azo reductases, beta-glucuronidase, dechlorinase and dehydrochlorinase were determined by anaerobic incubation of intestinal homogenates with 3,4-dichloronitrobenzene, methyl orange, p-nitrophenyl-beta-D-glucuronide, and p,p'-DDT respectively. Nitroreductase and azo reductase activities increased significantly with the appearance of anaerobes in the large intestine. No increase in either nitroreductase or azo reductase activities in the small intestine was found. The early and high level of beta-glucuronidase activity in the small and large intestines coincided with high numbers of coliforms recovered in 7 and 14 d animals. Dehydrochlorinase activity appeared early but was undetectable at both 21 and 28 d. Its activity increased at 35 d. Dechlorinase activity was variable in development. The rapid changes in the microbial flora and intestinal enzyme activities may influence the susceptibility of pre-pubescent rats to a variety of toxicants. Therefore, age-dependent toxicity may be important in the risk assessment of some environmental chemicals.

Characterization of Escherichia coli nitroreductase NfsB in the metabolism of nitrobenzodiazepines

“…Furthermore, nitroreduction of FZ under anaerobic condition showed a developmental increase beginning at 8 weeks of age. This may support the idea that nitroreductase activity in rat intestinal bacteria is significantly elevated after 28 days of age [21] since the growth of microbial population in GI tract increases extensively after neonate [34].…”

“…Escherichia coli (E. coli) is a typical coliform bacteria of the family Enterobacteriaceae in normal flora of animals [19]. In rat, E. coli strains inhabit in small intestine for metabolism of xenobiotics from host, where nitroreductase activities occur toward many nitroaromatic compounds [20][21][22]. Nitroreductases are a family of NAD(P)Hdependent flavoenzymes (using flavin mononucleotide as cofactor) that catalyze the reduction of the nitro groups of a wide range of nitroaromatic compounds [23].…”

Studies on the adsorption kinetics and isotherms for the removal and recovery of Methyl Orange from wastewaters using waste materials

“…In the Analytical Chemistry Laboratories it is mainly used as an acid base indicator due to its ability to function as weak acid as the 0304 aqueous solution of the dye has a pH value of approximately 6.5 (5 g/l, H 2 O, 20 • C) [27]. Microbial succession and intestinal enzyme activities in the developing rat has also been studied for the Methyl Orange [28] and the dye is found to increase their nitro reductase and azo reductase activities significantly with the appearance of anaerobes in the large intestine. Azo dyes are well known carcinogenic organic substances.…”

Fabrication of tin-doped zinc oxide by parallel flow co-precipitation with enhanced photocatalytic performance

“…Microbial succession and intestinal enzyme activities in the developing rat have also been studied for MO and the dye is found to increase their nitro and azo reductase activities significantly with the appearance of anaerobes in the large intestine [21]. Reductive enzymes in liver can also catalyze the reductive cleavage of the azo linkage to produce aromatic amines and can even lead to intestinal cancer [22,23].…”