Environmental Engineering Reference
In-Depth Information
30.3.4 Microbicidal Effect
The minimum inhibitory dosage of 10% of ZZ was established through a study that used
gram-positive and gram-negative bacterial strains and yeasts. It has been determined that
ZZ has a bactericidal effect on a great number of microorganisms. A speciic study made
possible to ascertain the microbicidal effect of ZZ on the pathogenic strains of
Vibrio chol-
erae
01 and
Corynebacterium diphtheriae
[17]
.
The study showed that in the case of some
strains, even <10% of ZZ was suficient. Thus, the use of ZZ in the puriication of water for
human consumption can prevent the infections caused by these two microorganisms as
well as the others showed in the Table 30.1.
Aeromona
was established as a genus in 1986. The pathogenic strains common in humans
are
A. hydrophila
,
A. caviae
,
and
A. veronii bv. sobria
. They live in waters of low saline content
and in such food as meat, milk, ice cream, and well water. The infective dose is 10
6
colony-
forming units (CFU)/mL [18]. These bacteria produce gastroenteritis from diarrhea to dys-
entery. Table 30.7 describes the results of the test that showed the bactericidal effect of ZZ
on
A. hydrophila
ATCC 7614. See that after 30 min, the bacteria were eliminated.
The infective dose of
Plesiomonas shigelloides
to produce diarrhea is approximately 10
6
CFU/mL. The time of incubation is from 1 to 14 days, and it can produce systemic infec-
tions in neonates and patients affected by hematological conditions, HIV and other ill-
nesses [19,20]. Table 30.8 shows the bactericidal effect of ZZ on these bacteria in drinking
water. The effect was observed after 30 min.
TABLE 30.7
Bactericidal Effect of ZZ on
Aeromona hydrophila
ATCC 7614
CFU
Time
ZZ Stirred
Control
ZZ Static
Control
0
2.6 × 10
9
2.6 × 10
9
2.6 × 10
9
2.6 × 10
9
15 min
4.6 × 10
3
1 × 10
8
4.6 × 10
6
1 × 10
8
30 min
-
1 × 10
7
-
1 × 10
7
1 h
-
1.6 × 10
7
-
6.5 × 10
7
2 h
-
6 × 10
7
-
3 × 10
7
3 h
-
1 × 10
7
-
6.2 × 10
7
TABLE 30.8
Bactericidal Effect of ZZ on
Plesiomonas
shigelloides
CNCTC 5132
CFU
Time
ZZ Stirred
Control
ZZ Static
Control
0
8 × 10
8
8 × 10
8
8 × 10
8
8 × 10
8
15 min
3 × 10
5
4.5 × 10
7
1.6 × 10
5
1.6 × 10
7
30 min
-
7.6 × 10
6
-
3.3 × 10
6
1 h
-
5.6 × 10
6
-
6.3 × 10
6
2 h
-
3.5 × 10
6
-
3.1 × 10
6
3 h
-
3.3 × 10
6
-
4.2 × 10
6
