In Vitro Efficacy of Myxococcus fulvus ANSM068 to Biotransform Aflatoxin B1

Aflatoxin B1 (AFB1) is commonly found in cereals and animal feeds and causes a significant threat to the food industry and animal production. Several microbial isolates with high AFB1 transformation ability have been identified in our previous studies. The aim of this research was to characterize one of those isolates, Myxococcus fulvus ANSM068, and to explore its biotransformation mechanism. The bacterial isolate of M. fulvus ANSM068, isolated from deer feces, was able to transform AFB1 by 80.7% in liquid VY/2 medium after incubation at 30 °C for 72 h. The supernatant of the bacterial culture was more effective in transforming AFB1 as compared to the cells alone and the cell extract. The transformation activity was significantly reduced and eradicated after the culture supernatant was treated with proteinase K, proteinase K plus SDS and heating. Culture conditions, including nitrogen source, initial pH and incubation temperature were evaluated for an optimal AFB1 transformation. Liquid chromatography mass spectrometry (LCMS) analyses showed that AFB1 was transformed to a structurally different compound. Infrared analysis (IR) indicated that the lactone ring on the AFB1 molecule was modified by the culture supernatant. Chromatographies on DEAE-Ion exchange and Sephadex-Molecular sieve and SDS-PAGE electrophoresis were used to determine active components from the culture supernatant, indicating that enzyme(s) were responsible for the AFB1 biotransformation. This is the first report on AFB1 transformation by a strain of myxobacteria through enzymatic reaction(s)

The impact of saturable absorber recovery time on hybrid mode-locked fiber lasers with near zero net dispersion

The hybrid mode-locking scheme holds great potential in obtaining high power ultrashort laser source since it overcomes low damage threshold, self-starting difficulty in single real saturable absorber (SA) or artificial SA mode-locking scheme. Here we numerically studied the effect of SA’s recovery time on the stability of laser output in an all polarization-maintaining (PM) Erbium-doped fiber laser with hybrid mode-locking scheme, operating at the near zero net dispersion. The mapping relationship between fiber fused angles of nonlinear polarization rotation (NPR) section and different mode-locking states is demonstrated. The proportion of stable single pulse operating points increased from 7 % to more than 77 %, as the recovery time of the SA was reduced from 10 ps to 0.1 ps. The results indicate that the laser output states with hybrid mode-locking scheme could be highly affected by the SA recovery time, when the cavity net dispersion is in near zero regime

Effect of Carnosine on Growth Performance, Carcass Characteristics, Meat Quality and Oxidative Stability in Broiler Chickens

The present study was conducted to evaluate the effect of dietary carnosine on growth performance, carcass characteristics, meat quality, and oxidative stability of muscle and blood in Arbor Acres broilers. A total of 180 1-d-old male broiler chicks were randomly assigned to 3 groups: group A, control feed; group B, 0.50% carnosine feed during d 1 to d 21; group C, 0.50% carnosine feed during d 22 to d 42. Birds were sacrificed at d 42. Live body weight, muscle color (L*, a*, b*), pH values at 0, 2, and 24h postmortem, meat shear force value (SFV), water loss rate, the amount of thiobarbituric acid reactive substances (TBARS), and total antioxidant capability (TAOC) in the blood and the muscle tissue were measured. Results showed that the growth performance of the chickens was not affected by dietary carnosine. The breast muscle weight and thigh muscle weight of group B and the thigh muscle weight of group C was significantly higher than that of group A (P<0.05). The SFV of the breast and the thigh muscle of group C and the SFV of the breast muscle of group B was significantly lower than that of group A (P<0.05). Neither the muscle color nor the pH values at 0, 2, and 24h postmortem were affected. The dietary carnosine decreased the TBARS values and increased the TAOC both in the blood and muscle significantly (P<0.01). These results suggest that dietary carnosine improves chicken meat quantity and quality