Laboratory studies on adhesion of microalgae to hard substrates

Adhesion of Chlorella vulgaris (chlorophyceae), Nitzschia amphibia (bacillariophceae) and Chroococcus minutus (cyanobacteria) to hydrophobic (perspex, titanium and stainless steel 316-L), hydrophilic (glass) and toxic (copper, aluminium brass and admiralty brass) substrata were studied in the laboratory. The influence of surface wettability, surface roughness, pH of the medium, culture age, culture density, cell viability and presence of organic and bacterial films on the adhesion of Nitzschia amphibia was also studied using titanium, stainless steel and glass surfaces. All three organisms attached more on titanium and stainless steel and less on copper and its alloys. The attachment varied significantly with respect to exposure time and different materials. The attachment was higher on rough surfaces when compared to smooth surfaces. Attachment was higher on pH 7 and above. The presence of organic film increased the attachment significantly when compared to control. The number of attached cells was found to be directly proportional to the culture density. Attachment by log phase cells was significantly higher when compared to stationary phase cells. Live cells attached more when compared to heat killed and formalin killed cells. Bacterial films of Pseudomonas putida increased the algal attachment significantly.