Antibacterial activity of endophytic fungi Caulerpa racemosa against Vibrio parahaemolyticus in Vaname Shrimp (Litopenaeus vannamei)

Vaname shrimp is an essential commodity in brackish water aquaculture and has high economic value. Infectious diseases are caused by bacteria of the genus Vibrio, one of which is Vibrio parahaemolyticus, and hinder the development of shrimp farming. The increasing bacterial resistance in aquaculture aggravates the situation. To overcome this problem, research into natural materials with new antibacterial activity is needed. Macroalgae are one of the natural materials suitable as a habitat for microorganisms, as they contain various organic substances that serve as nutrients for the growth of bacterial colonies or other microbes such as fungi. Therefore, this study aims to examine the antibacterial activity of endophytic fungi in symbiosis with Caulerpa racemosa against V. parahaemolyticus. C. racemosa from Karimun Jawa Island was isolated in PDA and incubated for seven days. After purification, five isolates showed antibacterial activity using the agar overlay method, and four isolates: C.1.BM, C.4.B, C.7.TM, and C.8.T, showed the best antibacterial activity. The result is that isolates C.1.BM and C.8.T belong to the species Aspergillus fumigatus, isolate C.4.B to the species Aspergillus oryzae, and isolate C.7.TM to the species Trichoderma reesei. The results of this study indicate the potential of the endophytic fungi C. racemosa to be used to prevent disease problems in aquaculture.