Abstract

Mycobacterium avium ssp. paratuberculosis (Map) causes Johne’s disease in ruminants, and implicated in the aetiology of human Crohn’s disease. The survival of Map in the environment and its ability to multiply inside a host has been reported, however, unknown by which mechanism. Biofilm formation by some species of mycobacteria is noted as a means of survival and host adaptation, with such knowledge lacking for Map. In this work, biofilm formation by 3 isolates of Map, 2 from the environment and 1 from a Crohn’s disease patient, was determined using spectrophotometric analysis. Since Map is fastidious and persists in water with or without nutrients, aqueous extract of schmutzdecke was employed to ascertain the impact of a complex microcosm of nutritional composition on biofilm formation by a fastidious slow growing Mycobacterium. Since cells must adhere on to a suitable surface in order to initiate biofilm formation, adherence assay was carried out firstly on 2 surfaces i.e. aluminium and stainless steel plates on which all the 3 Map isolates adhered, but greatly on the aluminium compared to the stainless steel. Secondly, biofilm formation by the isolates was determined on polyvinyl chloride (PVC) plates, and all were positive for biofilm formation. The extent of biofilm formation as influenced by distilled water (DW, control) alongside aqueous extracts of filtered and unfiltered schmutzdecke (FAES and UAES) was also determined statistically at P<0.05. The order of significance was 0.0004, 0.0307 and 0.0487 for DW, FAES and UAES respectively. This study showed that Map could form biofilm under conditions that its immediate environment provides, and could serve as a mechanism for its survival and thrive in the environment and host.

Keywords

adherence, biofilm formation, schmutzdecke, water treatment operations, Mycobacterium avium ssp. paratuberculosis