Relationship between various bacterial populations and coprostanol and cholesterol.

A year-long study was conducted at three different locations in Canada to evaluate the relationship between fecal sterols and bacterial populations. A statistical model was constructed to study the following: (i) seasonal variations in the sterols and bacterial parameters; (ii) the differences between morning and afternoon samples; (iii) the relationship between the two sterols (coprostanol and cholesterol) as well as their relationship to the bacterial parameters; and (iv) the geographical differences between the three sampling sites. Application of the model to the data indicated that (i) the relationship in receiving waters between coprostanol and cholesterol was found to be highly significant; (ii) at two sampling sites the relationship between fecal sterols and fecal coliforms was positively significant at the 5% level; (iii) at one sampling site there was a positive relationship between fecal sterols and the fecal coliform - fecal streptococcus ratio; and (iv) in a.m. vs. p.m. samples significant differences were noted in coliform, fecal coliform, and fecal streptococcus densities while no significant differences were found in heterotroph densities and coprostanol and cholesterol levels. Raw and treated sewage from four sewage-treatment plants were also studied to provide baseline control data. Data support the conclusion that while no consistent relationship exists between bacterial parameters and fecal sterols, fecal sterols could be considered as unequivocal indicators of the presence of fecal material in water.