Microfouling of manganese-oxidizing bacteria in Tuticorin harbour waters

Abstract

Implication of manganese-oxidizers in corrosion of various alloys stimulated the investigators to concentrate on these aspects. In the present study, an attempt was made to bring out the bacterial genera involved in the oxidation of manganese in biofilms. The materials immersed in sea water for biofilm formation included polyvinyl chloride (PVC), stainless steel (SS), brass and copper. The biofilm samples were analysed quantitatively and qualitatively for both heterotrophic bacterial population (HB) and manganese-oxidizing heterotrophic bacterial population (MHB). Both qualitative and quantitative examination of biofilms showed relatively poor population density on copper. Qualitative examination revealed the representation of both Gram-positive and Gram-negative bacteria on all materials. However, only Gram-positive groups, especially of the endospore-forming genus Bacillus and non-endospore forming genus Propionibacterium were observed on copper coupons. Gram-positive genera dominated over Gram-negative genera in most of the biofilms studied. The genera identified under manganese-oxidizing bacterial isolates were Bacillus, Staphylococcus, Synecoccus, Propionibacterium, Micrococcus, Pseudomonas and Vibrio. Among them, Bacillus species was most commonly encountered in all the materials studied. Potential measurements for SS316 showed positive shift. Analysis revealed enormous amount of manganese in the biofilms.