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Evaluation of four membrane filter media in anaerobic‐MF recovery of faecal coliforms from freshwater in Nigeria
Author(s) -
Ogan M.T.
Publication year - 1992
Publication title -
journal of applied bacteriology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.889
H-Index - 156
eISSN - 1365-2672
pISSN - 0021-8847
DOI - 10.1111/j.1365-2672.1992.tb01705.x
Subject(s) - fecal coliform , enterobacter , anaerobic exercise , microbiology and biotechnology , agar , veterinary medicine , membrane filter , biology , coliform bacteria , feces , enterobacteriaceae , escherichia coli , bacteria , ecology , water quality , membrane , medicine , physiology , biochemistry , genetics , gene
M.T. OGAN. 1992. MacConkey (MC), membrane lauryl sulphate (MIS), membrane faecal coliform amended with rosolic acid (MFC + R) and without the acid (MFC — R) were evaluated in the anaerobic membrane filtration (anaerobic‐MF) recovery of faecal coliform populations (FCs), genera and faecal coliform positive (FC‐positive) strains isolated from various sources of freshwater, i.e. rivers, rural wells, unchlorinated distributive supplies and hand pumps. Mean counts (x 10 2 /100 ml) of presumptive (typical) FCs varied from 13.69 (MC) to 40.81 (MLS) in river samples, and from 2.0 (MC) to 4.19 (MFC + R) in wells. The proportion of FC‐positive, typical FCs ranged from 48.66 (MIS) to 66.67% (MC) in rivers, and from 50 (MC) to 90.22% (MFC + R) in wells. More than 30% of the typical FCs from all sources on each medium was FC‐negative. These usually formed small ( ca 1.0 mm diam.) colonies on the test agar, and were prevalent in wells. Typical FCs and FC‐positive strains were not recovered from piped supplies and hand pumps. In spite of anaerobic incubation, non‐faecal coliforms (NFCs) were often higher than the FCs; the FC: NFC ratios for rivers ranged from 1.65 (MC) to 7.65 (MLS) and (MFC + R) but were < 1.0 for wells on each medium. Escherichia coli, Klebsiella and Enterobacter species were recovered on all media: approximately 35–64% of the strains confirmed as FCs were E. coli, 20–42% were Kl. pneumoniae. The FC counts on the media were variable, but the overall performance in recovering ‘true’ FCs was similar; < 70% of strains per medium were FC‐positive. None could count E. coli exclusively.