1. Introduction
For environmental engineers, microorganisms are important
for a number of reasons. First, pathogenic microorganisms represent
a threat to public health and must be eliminated from
potable water; second, biocatalytic microorganisms are used to
treat toxic pollutants (i.e., bioremediation) and thus should be
encouraged to thrive; and third, nuisance microorganisms upset
the reliable performance of bioprocesses. For environmental
engineers, mycobacteria represent all three types. For instance,
Gordonia (formerly Nocardia) amarae have been shown to be
a causative agent for the formation of filamentous nuisance biological
foam (e.g., nocardiafoam) on the surfaces of aeration
basins, secondary clarifiers, and anaerobic digesters in municipal
sewage treatment around the world [1–3]. The problem of
nocardiafoam has been studied for more than 30 years, and
∗ Corresponding author. Tel.: +1 513 556 2347; fax: +1 513 556 7326.
E-mail address: ipapauts@ececs.uc.edu (I. Papautsky).
the estimated total accumulative cost of incidences of nocardiafoam
disrupting the acceptable performance of sewage treatment
plants is of the order of 1 billion dollars [4].