Downregulation of Biofilm Formation Genes in Some Pathogenic Bacteria by Extracts From Two Algal Genera

Most infectious diseases are primarily caused by the growth of microorganisms called biofilms. The formation of bacterial biofilms enables microorganisms to inhabit biotic and abiotic surfaces which increases their resistance to antimicrobials. To control this issue, there is a critical need for novel approaches and compounds can suppress the expression or regulation of virulence genes. A potential method for disarming rather than eliminating bacterial pathogens is antivirulence therapy based on the blockage of biofilm pathways. In current study, the action of water, diethyl ether and acetone extraction on two types of algae namely Scenedesmus quadricauda and Chlorosarcinopsis eremi in their sub-inhibitory concentration (SIC) was investigated against Pseudomonas aeroginosa and Escherichia coli biofilm formation and their gene expression instead of killing them. The SIC values of each extract were determined by minimal inhibitory concentration (MIC) assay then gene expression products were assessed using Real-Time PCR (RT-PCR) when the cells were exposed to the SICs of algal extracts. Results revealed that the expression of ndvB (P. aeroginosa) & FimH (E. coli) genes that involved in biofilm formation was reduced by the extracts at their SICs. Diethyl ether was the best solvent with greater inhibitory activity followed by water and acetone against two pathogenic bacteria under this survey. Values of 25 mg/ml, 20 mg/ml for MIC and 15 mg/ml, 10 mg/ml for SIC were recorded by diethyl ether solvent against P. aeroginosa and E. coli respectively. According to biofilm detection, water extract was more efficient in S. quadricauda against P. aeroginosa and E. coli.