Microbially influenced corrosion (MIC) makes an important contribution
to corrosion in various industries. Considerable success has been ach
ieved by the use of biocides. Little information for controlling MIC i
s, however, available on the effectivity of biocides against sulphate-
reducing bacteria (SRB) due to the difficulties of culturing these org
anisms using conventional techniques. Conductance changes monitored us
ing the Malthus system were evaluated as an alternative method of esti
mating numbers of Desulfovibrio desulfuricans for laboratory biocide e
valuations. The correlation of log10) counts of Desulfovibrio cells in
iron sulphite (IS)-medium using conventional techniques with detectio
n times using the Malthus systems was highly significant (r = 0,974),
indicating that the Malthus system can be used as an alternative metho
d to conventional media for the enumeration of SRB. Growth studies of
Desulfovibrio using the Malthus system were useful in the evaluation o
f biocides. A 56 % and a 100 % kill was obtained when using 60 and 200
mg/l quaternary ammonium compounds (QAC), respectively.