Optimization of antagonistic activity of the extracellular compound Serratia plymuthica UBCF_13 against phytopathogenic fungi through the addition of carbon and nitrogen

Abstract

Serratia plymuthica UBCF_13 is one of the biocontrol bacteria that can suppress the growth of phytopathogenic fungi. Bacterial antifungal activity is influenced by several environmental factors, including the addition of carbon and nitrogen sources. This study aimed to determine the carbon and nitrogen sources that can encourage the maximum antagonistic activity of the extracellular compound from S. plymuthica UBCF_13. Carbon and nitrogen sources used in this study were glucose, sucrose, glycerol, ethanol, peptone, ammonium sulfate, tryptone, and yeast extract, with a concentration of 2 %. Bacterial extracellular compounds were applied to phytopathogenic fungi [Colletotrichum gloeosporioides, Sclerotium rolfsii, and Fusarium oxysporum] to see their antifungal activity. Data were statistically analyzed using one-way variance with DNMRT at the 5 % level. The best antifungal activity against C. gloeosporioides resulted from the addition of carbon source [ethanol] 22.28 % and nitrogen source [peptone] 16.94 %. The best antifungal activity against S. rolfsii fungi resulted from the addition of carbon source [ethanol] 14.67 % and nitrogen source [ammonium sulfate] 15.53 %. The inhibition ability of the extracellular bacterial compounds of S. plymuthica UBCF_13 in recording the growth of S. rolfsii with the addition of carbon and nitrogen is fairly low. S. plymuthica bacteria are less able to produce antifungal compounds that can suppress the growth of S. rolfsii fungi. The best antifungal activity against F. oxysporum fungi resulted from the addition of carbon source [ethanol] 8.47 % and nitrogen source [ammonium sulfate and tryptone] 28.25 % & 26.88 %.