Colony Structure of a Consortium of Nitrifying Bacteria

Colonies produced by a consortium of nitrifying bacteria were studied using light and electron microscopy. The colonies were obtained by direct plating of inoculum from a two-stage nonsterile chemostat fermentor and by repeatedly passing the microbial community of the fermentor through selective media containing ammonium or nitrite. The colonies studied can be characterized by a specific combination of six types of cells differing in their ultrastructure and spatial location within the colony. The types of cells occurring within a given colony were found to depend on the nitrogen compound present in the medium. As a result of our study, morphological features of colonial bacterial communities were identified. The proposed approach can be viewed as a method to describe microbial associations and communities.     

Electron-Microscopic Studies of the Colonies of an Alkylsulfonate-utilizing Bacterial Consortium

The light- and electron-microscopic analysis of the colonies of a bacterial consortium capable of utilizing alkylsulfonates, which are the main ingredients of waste from the synthetic rubber industry, revealed the presence of eight types of cells. All types of cells were gram-negative and differed in shape, size, and the presence of capsule and cytoplasmic inclusions. Three types of cells were present in all the colonies studied. The presence of the other types of cells depended on the inoculum used and on the composition of the growth medium.     

The Architectonics of Colonies of Bacillus subtilis 2335

Colonies grown from vegetative Bacillus subtilis 2335 cells had a standard structure, with bacillar cells occupying the whole colony volume. At the same time, the colonies of this bacterium grown from germinated spores had an abnormal structure characterized by the location of cells in a surface layer 100–200 m thick at the colony boundary with the air. The glycocalyx of the colonies grown from spores was characterized by a wetting angle _e of 120°–160°, whereas that of the colonies grown from vegetative cells had an angle _eas low as 5°–30°. It is suggested that spores and vegetative cells follow different strategies of substrate colonization and that the architectonics of bacterial colonies is determined by the physicochemical properties of the glycocalyx.     

Fine Chloroplast Structure in Cucumber and Pea Leaves Developed under Red Light

Photosynthetic activity, the content of various photosynthetic pigments, and the chloroplast ultrastructure were examined in the leaves of cucumber (Cucumis sativus L.) and pea (Pisum sativum L.) plants of different ages grown under red light (600–700 nm, 100 W/m²). In pea leaves tolerant to red-light irradiation, chloroplast ultrastructure did not essentially change. In the first true leaves of cucumber plants susceptible to red-light irradiation, we observed a considerable increase in the number and size of plastoglobules, the appearance of chloroplasts lacking grana or containing only infrequent grana, and stromal thylakoids. In the upper leaves of 22-day-old cucumber plants, the chloroplast structure was essentially similar to that of the control chloroplasts in white light, and we therefore suppose that these plants have acclimated to red light.