Enhanced Antimicrobials and Esterase Production Associated to Biofilm Formation by Two Estuarine Isolates in a Novel Polymethylmethacrylate Conico- Cylindrical Flask

A newly designed polymethylmethacrylate (PMMA) conico-cylindrical flask (CCF) with an inner arrangement consisting of eight equidistantly spaced rectangular strips mounted radially on a circular disk to provide additional surface area for microbial attachment was employed for antimicrobial compounds and esterase production by two biofilm-forming marine isolates, Streptomyces sundarbansensis sp nov. and BSE01, respectively. The design allowed comparison of production between (1) CCF with hydrophobic surface (PMMA-CCF), (2) CCF with hydrophilic glass surface (GS-CCF), and (3) standard unbaffled Erlenmeyer flask (EF). Compared to the EF, antimicrobial activity increased from 31 mm to 41 mm and esterase activity from 1070±10 U/mL to 3120±10 U/mL, respectively, in the PMMA-CCF but decreased from 31 mm to 17 mm for antimicrobial activity and from 3345±10 U/mL to 765±5 U/mL for esterase activity, respectively, in the GS-CCF. Growth of Streptomyces sundarbansensis sp nov. was also higher in the PMMA-CCF by 1.12 fold and 3.12 fold, respectively, compared to the EF and GSCCF. Similarly, growth of BSE01 was also higher in the PMMA-CCF by 391 fold and 1181 fold, respectively, compared to the EF and GS-CCF. Temporal pattern of biofilm progression based on two-channel fluorescence detection of extracellular polymeric substances and whole cells in a confocal laser scanning microscope followed by application of PHLIP and ImageJ volume viewer software demonstrated formation of matured, stable, welldeveloped, thick biofilm on PMMA in contrast to glass surface for both the isolates. Thus, antimicrobial compounds and esterase production were positively associated with vessel surface area and hydrophobicity, suspended cell growth, and biofilm formation.