In Vitro Efficacy of Myxococcus fulvus ANSM068 to Biotransform Aflatoxin B1

Abstract

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 Evolutionary Dynamics in the Research on Aflatoxins During the 2001-2010 Decade

“…Enzymes of diverse origins may also be a useful tool to reduce the aflatoxin contamination of different matrices, as it was suggested by Wang et al (2011). In line with these observations, microorganisms may have advantages with respect to the use of a purified enzyme, since they provide a subset of metabolic pathways that potentially could reduce the aflatoxins levels (Guan et al, 2010).…”

Aflatoxin B 1 degradation by liquid cultures and lysates of three bacterial strains

“…Conversely, AFB 1 was found to be stable in the presence of PBS and protease inhibitor cocktail. However, a 100% degradation of AF was observed by Teniola et al (2005) for intracellular extracts of R. erythropolis and Mycobacterium fluoranthenivorans after 8 h as well as a 74% degradation by cells of Flavobacterium aurantiacum in 68 h (Ciegler et al, 1966), meanwhile a degradation of ˂20% was observed for cell extracts of Myxococcus fulvus ANSM068 (Guan et al, 2010).…”

“…Subsequent cell lysis was done as previously described in Section 2.3. Heat inactivation of the lysates was done following the method described by Guan et al (2010), and the effect of proteinase K treatment on the lysates was investigated using the method of Smiley and Draughon (2000) by exposing them to 1 mg/ mL proteinase K (Thermo Scientific, South Africa). The obtained lysates were incubated with AFB 1 at 37°C for 3, 6, 12, 24 and 48 h. Extraction, detection and quantification of AFB 1 were done as earlier described in Section 2.3.…”

Strategies and Methodologies for Developing Microbial Detoxification Systems to Mitigate Mycotoxins

“…A number of studies have evaluated intrinsic factors, including carbon source [26,34], nitrogen source [26,34,88], vitamins [26], metals ions [12,34,46,89,90,91,92,93], enzyme inhibitors and promoters [52,89,90,91,92,93,94], initial concentration of mycotoxins [93,95], initial concentration of cells [53,95] and initial pH value [12,14,17,26,31,34,41,46,54,60,88,89,95,96], as well as extrinsic factors, including temperature [12,14,17,25,26,31,34,38,41,46,52,54,60,88,89,95,96], aeriation (shaking rate) [26], oxygen preference [14], as well as pre-incubation [26] and incubation time [34,97]. The experimental designs and optimized biotransformation conditions are summarized in Table 2.…”