biologia - Studia

V. MUNTEAN, C.-G. MAIER, R. CARPA, C. MUREŞAN, A. C. FARKAS
100000
10000
Total coliforms/l
1000
100
10
1
P1 P2 P3 P4 P5
Sampling site
Spring Summer Autumn Winter
Fig. 1. The number of total coliforms (logarithmic expression).
One can notice that: strain 1 (S1) gave positive results only for indole
production and methyl red test; strain 2 (S2) was positive for methyl red test, citrate
utilization and urea hydrolysis; strain 3 (S3) was positive for Voges-Proskauer test,
citrate and malonate utilization, and for urea hydrolysis; strain 4 (S4) was positive for
six tests and negative only for the Voges-Proskauer test. According to these results, we
assume that the four analysed strains belong to the following bacterial genera:
Escherichia (S1), Klebsiella (S2), Enterobacter (S3) and Citrobacter (S4).
We notice the efficiency of the water treatment plant in Gilău. The applied
treatment methods assure the complete elimination of coliforms in water, as the
regular analyses at the treatment plant demonstrate. But we also notice the high
negative potential of the permanently increasing number of habitations built along
the river upstream the water treatment plant. The attention must be watchful and
permanent, taking into account that the coliforms are discharged daily in numbers
of billions by each human or animal being, in their faeces. And what is more
important, the presence of coliforms indicates the possible presence in water of the
pathogenic enteric bacteria.
134