Since the beginning of the civilization, humans have domesticated not only animals and plants, but also different kinds of microbes to produce beer, wine, cheese, yogurt, soy sauce, and more. Although researchers have studied the plant and animal domestication comprehensively, it is still a mystery on how domestication changes microbial behavior on a genetic scale. In this article, researchers at Vanderbilt University try to compare the genetic profiles between Aspergillus oryzae, the domesticated microbes, with its wild type relative, Aspergillus flavus to unveil the mystery of microbial domestication.
The research led by a graduate student, John Gibbons, starts with charting the genetic profiles of both Aspergillus oryzae and Aspergillus flavus, and comparing their genome sequences. The results show that both species share 99.5 percent of their genome, which is really surprising considering both have noticibly different behavior. A. oryzae is a non-toxic microbe, which is commonly used to produce delicacies through fermentation process. A. flavus, on the other hand, is a destructive agricultural pest that produces alfatoxin.
The study suggests that the domesticated A. oryzae might come from A. flavus-like species that experienced a genome remodeling, which eventually changed its metabolic system. The process was probably caused by the exposure of nutrient-rich environment by sake brewer in the past, which made the microbes increase its primary metabolism (grow faster) and decrease its secondary metabolism (produce alfatoxin). This environment change created by humans slowly turned the A.flavus-like species into A. oryzae, a domesticated microbe by altering its genetic makeup.
Even though the domestication process of animals and plants is mainly focused on faster growth rate or enlarged crop, the domestication process of microbes focuses on metabolic changes in enzyme and energy production. Further research needs to evaluate on the time length needed to domesticate microbes, which can later be utilized for beneficial uses.