ECOLOGICAL SYSTEMS
29
bacterial forms were found to adversely affect the growth of algae (Table
1). Four of six bacteria tested decreased algal growth from 5 to 13 per
cent; however, the effects were not additive because the combined effect of
the bacteria was no greater than that of each bacterium acting independ-
ently.
TABLE 1.
Effects on bacteria on the growth of Clilorella pyrenoidosa
TX71105, bacterial growth in algal cultures, and bacterial contri-
bution to culture mass
(Ward et al., 1964)
|
Bacterium |
Algal growth with bacteria» |
Viable bacteria | |||
|
0.D. |
Cell No. |
Dry Wt.b |
No. XlOtyml |
% Dry Wt. | |
|
Mima polymorpha |
104 |
80 |
-95 |
311.3 |
LÔ3 |
|
Bacillus, gram neg. |
-→ |
80 |
91 |
13.6 |
0.71 |
|
Bacterium anitratum |
89 |
77 |
87 |
14.5 |
0.98 |
|
Bacterium anitratum |
98 |
100 |
102 |
1.2 |
0.56 |
|
(atypical strain) | |||||
|
Pseudomonas aeruginosa |
101 |
80 |
89 |
0.4 |
0.01 |
|
Aerobacter cloacae |
103 |
101 |
103 |
22.2 |
0.25 |
|
Combined bacteriac |
91 |
85 |
88 |
16.1 |
0.93 |
Data are means of six or more replicates corrected for initials and
^expressed as per cent of bacteria-free controls,
bcorrected for contribution of bacteria,
cfirst five bacteria listed.
We also found that heterotrophic bacteria are capable of excellent growth
on inorganic algal medium after the algae have been removed (Figure 4),
ALGAL EFFLUENT
GRAM NEGATIVE BACILLUS
---------------------------1---------------------------1----------------------------------------------------------------------------------------------------------------1
0 4 8 24
TIME (HOURS)
FIGURE 4-GROWTH OF A GRAM NEGATIVE
BACILLUS IN EFFLUENT KNOP'S SOLUTION
FROM 24 - HOUR AXENIC CHLORELLA
PYRENOIDOSA TX 71105 CULTURES (WARDet αl,1964)