Microcapsules containing Serratia marcescens control white mold

Microcapsules produced with the bacterium Serratia marcescens G4 achieved 55,84 percent control of soybean sclerotinia in a pot experiment. A study by Chinese researchers evaluated the optimization of the fermentation medium, the preparation of the G4Ms formulation, and the effect of the biological agent against Sclerotinia sclerotiorum (DOI 10.1002/ps.71092).

Under initial cultivation conditions, the optical density of the G4 strain reached 2,241 after 12 hours. Sucrose and soy peptone performed best as carbon and nitrogen sources. Response surface optimization indicated a medium with 13,21 grams per liter of sucrose, 10,33 grams per liter of soy peptone, 10,95 grams per liter of yeast extract, and 10 grams per liter of sodium chloride. With this composition, the predicted optical density rose to 2,474. The increase reached 10,4 percent.

The best growing conditions included a temperature of 35 degrees Celsius, pH 7,0, inoculum of 3 percent by volume, agitation of 155 revolutions per minute, and a working volume of 50 milliliters.

Efficiency of microcapsules

G4M microcapsules were prepared with 80 percent maltodextrin. The formulation showed greater storage stability, greater biofilm formation, and greater inhibitory activity compared to free G4 cell lines.

In addition to controlling sclerotinia disease in the pots, the application of microcapsules increased enzymatic activity in the soil and microbial diversity. According to the scientists, the results indicate the potential of the G4Ms formulation as a biocontrol agent against soybean sclerotinia disease caused by Sclerotinia sclerotiorum.