**6.3 Molecular and physiochemical methods**

Genes encoding polyketide synthase I and II (PKS-I and PKS-II), and nonribosomal peptide synthetases (NRPS), are responsible for synthesis of novel AQS compounds in rare actinobacteria [138, 144]. PCR Screening of a given bacterium for these genes is helpful in detecting the presence of quorum quenching activity [145]. Purified compounds isolated from the broth cultures of such bacteria can be further subjected to Physiochemical screening methods such as UV–Vis spectrophotometry, TLC to determine the nature of compound which exhibits AQS activity [138]. Some strains of Nocardia [146] and Micromonospora [147] are subjected to such studies and novel AQS compounds were found.
