Biofilm formation by Mycobacterium avium ssp. paratuberculosis in aqueous extract of schmutzdecke for clarifying untreated water in water treatment operations.
AIMSTo determine the effect of aqueous extract of schmutzdecke on adhesion and biofilm formation by three isolates of Mycobacterium avium ssp. paratuberculosis (Map) under laboratory conditions.\n\nMETHODS AND RESULTSStrains of Mycobacterium avium ssp. paratuberculosis in aqueous extract of schmutzdecke were subjected to adhesion tests on two topologically different substrata i.e. aluminium and stainless steel coupons. Biofilm formation was then monitored in polyvinyl chloride (PVC) plates. All the three strains adhered onto both coupons, howbeit greatly on aluminium than stainless steel. In the PVC plates, however, all strains developed biofilms which were observed by spectrophotometric analysis.\n\nCONCLUSIONSThe environmental isolates of Map attained higher cell proliferation in both filtered and unfiltered aqueous extracts of schmutzdecke (FAES and UAES respectively) compared with the human isolate. Furthermore, the results showed that irrespective of the media used, Map might have developed biofilm by its genetic competence to do so under favourable conditions that the immediate environment might have provided.\n\nSignificance and impact of the studyComposites of the schmutzdecke which is the dirty layer formed within 10 to 20 days of operation of a slow sand filter bed had a proliferative effect on Map. Therefore when entrapped, Map could form a biofilm and access human populations through potable water. Therefore, schmutzdecke should be monitored and scraped periodically to curtail its support for environmentally persistent pathogens that can pose health risks to humans.\n\nHighlightsO_LISchmutzdecke; a reservoir of nutrient composites atop slow sand filter bed\nC_LIO_LIAdhesion by Map on aluminium and stainless steel coupons was achieved\nC_LIO_LIMap strains from water sources developed biofilms better than the human strain\nC_LIO_LIIn distilled water, biofilm formation by all strains was evident\nC_LIO_LIProtracted build-up of schmutzdecke may proliferate waterborne pathogens\nC_LI