Inhibition of quorum sensing mediated biofilm development and virulence in uropathogens by Hyptis suaveolens.

Bacterial urinary tract infections (UTIs) are the most common nosocomial infections, accounting for about 40 % of all hospital-acquired infections. The bacterial spectrum of nosocomial UTIs is broad and the treatment of UTIs is becoming difficult owing to the emergence of drug resistance. Therefore, it is reasonable to investigate novel and alternative therapeutic strategies to treat UTIs. Since UTIs are caused by uropathogens with quorum sensing (QS)-dependent biofilm forming abilities, interruption of QS systems may be a novel approach to combat drug resistance. In the present study, a methanol extract (and hexane extract derived from it) of the medicinal plant Hyptis suaveolens (L.) were shown to have anti-QS activity against the biosensor strain Chromobacterium violaceum (ATCC 12472). Furthermore, the hexane extract of H. suaveolens (HEHS) inhibited biofilm formation by uropathogens such as Escherichia coli, Proteus vulgaris, Proteus mirabilis, Klebsiella pneumoniae and Serratia marcescens. HEHS promotes the loosening of biofilm architecture and strongly inhibits in vitro biofilm formation by uropathogens, which was more apparent from microscopic images. In addition to this, HEHS reduces the production of QS-dependent virulence factors like protease and hemolysin, along with motility. The partial purification and GC-MS analysis of the active fraction revealed the presence of several therapeutically important compounds which may synergistically act on the uropathogens and possibly reduce the QS-dependent phenotypes. These findings suggest HEHS as potential phytotherapeutic agent which can be employed to formulate protective strategies against biofilm linked infections caused by uropathogens.

Amylase enzyme from Bacillus subtilis S8-18: a potential desizing agent from the marine environment.

The present study is aimed at developing an economical medium for the production of α-amylase from Bacillus subtilis S8-18, a marine sediment isolate from Palk Bay, with various agricultural by-products that are cheap and rich in starch. These products include wheat bran, wheat husk, rice bran, rice husk, and potato peel and are used to replace soluble starch present in the Luria Bertani (LB) broth (synthetic medium). The rice husk was found to be the best to influence enzyme production significantly (61,186 IU mL⁻¹) when compared with the yield of 30,026 IU mL⁻¹ obtained by commercial starch. Hence, LB broth containing rice husk was considered an economical medium. In addition, the effect of various nutritional and physiological factors on enzyme production was also investigated. Furthermore, the desizing efficiency of α-amylases produced by synthetic and economical media was evaluated through various assays like reducing sugar estimation, weight loss assay, drop absorbency assay, scanning electron microscopy, and Fourier transform infrared analyses. In addition, a commercial α-amylase from B. subtilis was also used in desizing analyses for comparative purposes. It revealed that the α-amylase from the economical medium was as effective in desizing the cotton fabrics as that of the commercial enzyme and much superior to the enzyme produced through the synthetic medium.