ARS | Publication request: Mathematic modeling for optimum conditions on aflatoxin B1 degradation by the aerobic bacterium Rhodococcus erythropolis

Submitted to: Toxins
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 31, 2012
Publication Date: November 6, 2012
Citation: Kong, Q., Zhai, C., Guan, B., Li, C., Shan, S., Yu, J. 2012. Mathematic modeling for optimum conditions on aflatoxin B1 degradation by the aerobic bacterium Rhodococcus erythropolis. Toxins. 4:1181-1195.

Interpretive Summary: Aspergillus flavus produces aflatoxins, the most potent cancer-inducing natural compounds. Currently there is no effective strategy to stop fungal infection in preharvest crops and post harvest grains. Removal of aflatoxins from contaminated food and feed source is not only less effective but costly. In previous study, the authors have identified a marine bacterial strain that is capable of degrading aflatoxin B1. In this study, using mathematic modeling method, the authors reported the optimal conditions for the degradation. This information is important since it opened the possibility for devising strategy in control aflatoxin contamination in food and feed through enzymatic degradation.

Technical Abstract: Response surface methodology was employed to optimize the degradation conditions of AFB1 by Rhodococcus erythropolis in liquid culture. The most important factors that influence the degradation, as identified by a two-level Plackett-Burman design with 6 variables, were temperature, pH, liquid volume, inoculum size, agitation speed and incubation time. Central composite design (CCD) and response surface analysis were used to further investigate the interactions between these variables and to optimize the degradation efficiency of R. erythropolis based on a second-order model. The results demonstrated that the optimal parameters were: temperature, 23.2'; pH, 7.17; liquid volume, 24.6 mL in 100-mL flask; inoculum size, 10%; agitation speed, 180 rpm; and incubation time, 81.9 hr. Under these conditions, the degradation efficiency of R. erythropolis could reach 95.8% in liquid culture which was increased by about 3 times as compared to non-optimized conditions. The result by mathematic modeling has great potential for aflatoxin removal in industrial fermentation such as in food processing and ethanol production.