58 Environmental Biotechnology
Figure 3.2 Endocrine disrupters
to human health in drinking water although, this does not address the problem
affecting hormone-susceptible organisms living in contaminated water and thus
exposed to this potential hazard.
New discoveries
Almost daily, there are novel bacteria being reported in the literature which
have been shown to have the capacity to degrade certain xenobiots. Presumably
the mutation which occurred during the evolution of the organism conferred an
advantage, and selective pressure maintained that mutation in the DNA, thus pro-
ducing a novel strain with an altered phenotype. Some example of such isolates
are described here. Reference has already been made to some PAHs mimicking
oestrogen which earns those chemicals the title of ‘endocrine disrupters’. This
is in addition to some being toxic for other reasons and some being carcino-
genic or teratogenic. The PAHs are derived primarily from the petrochemicals
industry and are polycyclic hydrocarbons of three or more rings which include
as members, naphthalene and phenanthrene and historically have been associated