Cladosporium sphaerospermum extract inhibits quorum sensing associated virulence factors of Serratia marcescens .

is now becoming a propensity for its highly antimicrobial-resistant clinical infections. Currently, it provides a novel strategy to prevent and control microbial infection by regulating quorum sensing (QS). Deep-sea-derived fungi are rich in QS bioactive constituents. In this work, the extracts from SCSGAF0054 showed potent QS-related virulence factors and biofilm-inhibiting activities against NJ01 The swimming motility and multiple virulence factors such as prodigiosin, exopolysaccharide (EPS), lipase, protease and hemolysin were moderately inhibited by the extracts at varied concentrations. The confocal laser scanning microscope (CLSM) and scanning electron microscope (SEM) images revealed that extracts moderately arrested biofilm formation and cell viability. Further, real-time quantitative PCR (RT-qPCR) analysis revealed that expressions of genes associated with virulence factors, , , , , , , , and , were significantly down-regulated compared with control. In addition, the extracts combined with imipenem inhibited the QS system of NJ01, disrupted its preformed biofilm, released the intra-biofilm bacteria and killed the bacteria gradually. Therefore, the extracts combined with imipenem can partially restore bacterial drug sensitivity. These results suggest that the extracts from SCSGAF0054 effectively interfere with the QS system to treat infection alone or combining with classical antimicrobial drugs.