Conspicuous Veils Formed by Vibrioid Bacteria
Conspicuous whitish veils which cover the surface of sulfidic sediment) at water depths of 0 to 0.5 m in Nivå Bay were observed from May to September in the years 1999 to 2001. Mostly present in calm waters briefly after periods of windy weather, the veils were developed when wind actions bring decaying sea grass and macro algae within the sulfidic marine sediment near the place where the veil develops. This propelled the researchers to examine and study the morphology and veil formation of the organism causing this veil formation.
The morphology and behavior of an unknown bacterium was illustrated by the authors of the original article. The unknown bacteria form a conspicuous veil on marine sediments that are sulfidic. The unknown bacteria, when examined under binocular compound microscopes, are described as colorless, vibroid-shaped, and gram-negative. Further examination using binocular compound microscopes also reveal that the unknown bacteria multiply by binary division and have numerous poly-beta-hydroxybutyric acid spherical inclusions. Their flagella are described in the original article as bipolar polytrichous and display a unique swimming pattern of rotating and translating along their short axis.
A benthic gradient chamber was used for laboratory enrichment of the veil-forming bacteria. Flat glass capillaries were examined and studied with the use of binocular compound microscopes. The capillary openings were sealed with petroleum jelly to prevent evaporation of air.
Aside from microscopic observations using binocular compound microscopes, in situ video microscopy was also made in the samples. This was accomplished by connecting a digital video recorder into a compound microscope and illuminating the sample with collimated light beam to perform darkfield microscopy. This set-up visualized the flow fields of the samples. It was discovered that the bacteria was evenly distributed in the oxic side of the translucent veil and that the advective water flow was always parallel to the veil surface.
Because of the fragile structure of the veils, it was impossible to successfully transport them into the researcher’s laboratory. Instead, veil formation in sediment formation was successfully induced under controlled environment in the laboratory. Further examination of the veil formed by the unknown bacteria using binocular compound microscopes revealed homogenous whitish translucent appearance, as described in the original article. It was also discovered that after four weeks, the veil was replaced by phototrophic bacterial mat.
Light microscopy using binocular compound microscopes was able to illuminate that the whitish translucent veils were made up predominantly of vibroid-shaped bacteria that are colorless. The unknown bacteria,a ccording to the research article, was obligately microaerophilic. They prefer oxygen concentration of 2 ?M O2. The bacteria become immotile when they are exposed to anoxia (no oxygen) or high oxygen concentrations
Only the morphology and veil formation of the unknown bacteria was discussed in the research article. Further studies are still needed to know the physiological properties of this new bacteria species. The ecological relevance and biogeography of the new bacteria species is also unknown and needs further research. It can only be assumed that coastal sulfidic sediments with a high load of organics will be able to produce the translucent veil caused by these vibroid-shaped unknown bacteria.
