Improved Neomycin Sulfate Potency in Streptomyces fradiae Using Atmospheric and Room Temperature Plasma (ARTP) Mutagenesis and Fermentation Medium Optimization

To improve the screening efficiency of high-yield neomycin sulfate (NM) Streptomyces fradiae strains after mutagenesis, a high-throughput screening method using streptomycin resistance prescreening (8 μg/mL) and a 24-deep well plates/microplate reader (trypan blue spectrophotometry) rescreening strategy was developed. Using this approach, we identified a high-producing NM mutant strain, Sf6-2, via six rounds of atmospheric and room temperature plasma (ARTP) mutagenesis and screening. The mutant displayed a NM potency of 7780 ± 110 U/mL and remarkably stable genetic properties over six generations. Furthermore, the key components (soluble starch, peptone, and (NH4)2SO4) affecting NM potency in fermentation medium were selected using Plackett-Burman and optimized by Box-Behnken designs. Finally, the NM potency of Sf6-2 was increased to 10,849 ± 141 U/mL at the optimal concentration of each factor (73.98 g/L, 9.23 g/L, and 5.99 g/L, respectively), and it exhibited about a 40% and 100% enhancement when compared with before optimization conditions and the wild-type strain, respectively. In this study, we provide a new S. fradiae NM production strategy and generate valuable insights for the breeding and screening of other microorganisms.

Manufacturing of a New Selective Membrane Electrode for Neomycin Sulfate and its Estimation by Potentiometric Method

The research aims to prepare a new ionic membrane selective electrode for NYM Neomycin based on tungstophosphoric acid (TPA), Poly Vinyl Chloride (PVC) and DPPH (Di-Butyl Phthalate). It was found that the electrode is sensitive to concentrations ranging between (1 x 10-1-1 x 10-5) mol/L, and it gave a Nernstian response of (29.7 mV/decade) and a correlation coefficient (r) of (0.9939). The factors affecting the response of the electrode were studied, as it was found that the best concentration of the internal filling solution was (1 x 10-3) mol/L, and that the best pH range in which the electrode worked was between (3.5-1.5) and the best Nernstian response at pH (pH = 2.5) The effect of temperature was also studied, as it was found that the best temperature was (25°C) and the response time of the electrode was between (20-40) seconds. It was also found that the chronological age of the electrode was (25) days. The selectivity coefficient (Ki,jpot) was calculated in the presence of negative and positively charged interfering ions.

Estimating the Rates of Acquisition and loss of Resistance of Enterobacteriaceae to Antimicrobial Drugs in Pre-Weaned Dairy Calves

The objective of this study was to investigate the effect of the antimicrobial drugs (AMD) on the shedding of resistant Enterobacteriaceae in feces of pre-weaned dairy calves. The AMD considered were ceftiofur, administered parenterally, and neomycin sulfate added in milk replacer and fed to calves during the first 20 days of life. Fifty-five calves, aged one to three days, were enrolled and followed to 64 days. Fecal samples were collected three times/week and treatments recorded daily. Enterobacteriaceae were quantified for a subset of 33 calves using spiral plating on plain, ceftiofur supplemented, and neomycin supplemented MacConkey agar. Negative binomial models were used to predict the association between treatment with AMD and the gain and loss of Enterobacteriaceae resistance over time. Acquisition of resistance by the Enterobacteriaceae occurred during treatment and peaked between days three to four post-treatment before decreasing to below treatment levels at days seven to eight post-treatment. Acquisition of neomycin resistance was observed on the first sampling day (day four from the start of feeding medicated milk replacer) to day eight, followed by cyclical peaks until day 29, when the Enterobacteriaceae counts decreased below pre-treatment. Enterobacteriaceae resistance against both AMD increased after AMD administration and didn’t return to pre-therapeutic status until seven or more days after therapy had been discontinued. The study findings provide valuable insights into the dynamics of Enterobacteriaceae under routine AMD use in calves.