Aerobic heterotrophic bacteria associated with oyster larvae feed
algae Isochrysis galbana, Monochrysis lutheri and Pseudoisochrysis
paradoxa were isolated and enumerated. The bacterial numbers ranged
from 7.8x10³ to 3.9x10⁶ CFU per ml. The bacteria associated with
Pseudoisochrysis sp. were identified and the majority of isolates
belonged to genera Leucothrix (51%). Also present were members of
Pseudomonas III sp. (19.1%), atypical Moraxella sp. (16.8%), Moraxella
sp. (7.2%) and Flavobacterium sp. (5.9%).
The growth of bacteria on marine agar was fastidious and took four
days to form visible colonies. None of the bacterial isolates grew in
buffered salt broth in which the algae had been grown. Marine broth
supplemented with 0.1% beef extract best supported the growth of the
isolates, while ferric citrate (3x10⁻⁴ M) supported their growth in
buffered salt broth.
The role of algae as a solid support for bacteria was investigated
by studying the attachment of bacteria on glass slides suspended in the
growth medium. The percent of Leucothrix sp. attached to the slide was
2.1-3.0%. This was four to six times greater than that of Staphylococcus
(0.5%), an organism well known for its commensal growth on skin
and mucus membranes of man and animal.
Hydrophobic attraction, which is thought to play an important role
in the orientation of bacteria to solid surfaces, was studied by measuring
the adsorption of bacteria on hydrocarbons introduced to a bacterial
suspension. Leucothrix sp. exhibited the strongest affinity, whereas
Flavobacterium sp. and Pseudomonas sp. adsorbed the least.
An attempt to obtain an axenic culture of algae by antibiotic
treatment was unsuccessful due to the detrimental effect of antibiotics
to both algae and bacteria. / Graduation date: 1982
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/26003 |
| Date | 04 June 1981 |
| Creators | Johnson, Lynn I. |
| Contributors | Lee, Jong S. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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