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 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.