ABSTRACT
Samples of fresh faeces were obtained from a free-range chicken source; three commercial chicken farms and a commercial ostrich farm; all located around Bulawayo City; Zimbabwe; in order to determine the antibiotic resistance profile of selected bacterial isolates of interest in food-related human infections. Samples were prepared at various dilutions and plated on selective media for Coryneforms; Escherichia coli; Enterococcus faecalis and Pseudomonas. The targeted bacteria were isolated as pure cultures and tested for antibiotic resistance to ampicillin; chloramphenicol; oxytetracycline; sulphonamide; streptomycin and tetracycline. Isolates from the faeces of chickens and ostriches in the commercial farms were found to be generally more resistant to streptomycin; tetracycline and oxytetracycline as compared to those from the free- range chickens. This study emphasizes the need to monitor antibiotic resistance genes in the environment and to curb/curtail antibiotic use for growth promotion in farm animals; particularly in developing countries; as continued use will only add to the growing problem of microbial antibiotic resistance
Subject(s)
Chickens/parasitology , Drug Resistance , Enterococcus faecalis , Escherichia coliABSTRACT
Polyamine concentrations have been determined at intervals in suspension cultures of Paul's Scarlet rose cells during a culture period of 2 weeks. The mean concentrations of the putrescine, spermidine and spermine in the cells of the inocula were respectively 73, 70 and 13 nmol/g fresh weight. Putrescine at fitst increased with a peak (160 nmol/g) after 6 h, declined to a minimum (14 nmol/g) after 2-3 days, increased to a second peak (180 nmol/g) after 5-6 days, and then declined slowly to the concentration of the inoculum (taken on day 14). Spermidine rose slowly (×2.6) to a broad peak over 3-6 days (180 nmol/g), then declined slowly to the concentration in the inoculum. Spermine showed a rapid increase to a peak (130 nmol/g) after 2-3 days, and then declined rapidly, reaching the inoculum concentration by day 6. In one experiment the three amines showed a minor peak at day 11. Changes in spermine and RNA contents appeared to be correlated. DNA content reached a peak after that of the RNA (day 3) and did not appear to be correlated with the content of putrescine or the polyamines.
ABSTRACT
Induction of nitrate reductase (EC 1.6.6.1) activity was measured in Paul's Scarlet rose cell suspensions cultured in media containing nitrate (NO 3 (-) ) or urea (U) as nitrogen source, and with (+Mo) or without molybdenum (-Mo). There was a lag of 30 min during induction by NO 3 (-) in +Mo cultures but no lag occurred during induction after adding Mo to NO 3 (-) -Mo or to U-Mo cultures preincubated with NO 3 (-) . Actinomycin D, cycloheximide, and puromycin completely blocked induction by NO 3 (-) , but had no effect on the initial rate of induction by Mo. Cycloheximide and puromycin blocked induction by NO 3 (-) more quickly than actinomycin D. Induction by NO 3 (-) appeared to involve mRNA-dependent synthesis of apoprotein followed by rapid activation with molybdenum in intact cells independently of protein synthesis. Nitrate-induced apoprotein appeared less stable than the holoenzyme. When induced by NO 3 (-) in the absence of Mo, apoprotein concentration was about half the amount of maximally induced nitrate reductase. Cycloheximide stabilised preformed nitrate reductase which disappeared steadily in the presence of puromycin. Apoprotein was not stabilised by either antimetabolite.
ABSTRACT
Growth and nitrate reductase activity were measured in Paul's Scarlet rose cell suspensions, cultured in media purified from molybdenum and containing nitrate or urea as sole nitrogen source with or without added Mo. Urea could replace nitrate to yield 80% of the fresh weight in nitrate medium. Nitrate reductase activities were compared by in vivo and in vitro assays. The latter varied due to inactivation during extraction. Compared with activities in cells in complete NO3 (-) medium, activity in NO3 (-)-Mo cells was reduced to 30% and, in urea-grown cells, to trace amounts. Increases in nitrate reductase activity were found when NO3 (-) alone was added to NO3 (-) or urea+Mo cultures. In NO3 (-)-Mo cultures, Mo alone or with NO3 (-) caused a similar increase in activity, whereas urea-Mo cultures required both NO3 (-) and Mo for enzyme induction.
