Phylogenetic diversity of Bacteria - Cytophagales, Flavobacteriales, and Spinghobacteriales

8 important questions on Phylogenetic diversity of Bacteria - Cytophagales, Flavobacteriales, and Spinghobacteriales

Describe the characteristics of Cytophagales and their role in cellulose degradation.

ytophagales are mainly obligate aerobes, gliding gram-negative rods specializing in the degradation of complex polysaccharides, particularly cellulose. They are prevalent in toxic soils and freshwaters and can be isolated by placing soil on cellulose filter paper.

Explain the mechanisms of cellulose degradation by Cytophagas and mention a species that differs in cellulose degradation.

Cytophagas primarily degrade cellulose through the free cellulase mechanism, where cells secrete extracellular enzymes degrading insoluble cellulose outside the cell. Cytophaga hutchinsonii, however, lacks processive cellulases and requires physical contact with cellulose fibers for degradation.

What are some diseases caused by fish pathogens within the order Cytophagales, and what conditions favor these diseases?

Diseases include columnaris disease (Cytophaga columnaris) and cold-water disease (Cytophaga psychrophila). These affect stressed fish, especially those in high-density or pollutant-receiving environments like fish hatcheries.
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Describe the characteristics of Flavobacteriales and their abundance in marine environments.

Flavobacteriales are typically aerobic chemoorganotrophs, gram-negative rods with gliding motility. They are abundant in marine waters, including polar environments. Flavobacterium species are primarily found in aquatic habitats and food-processing plants.

Which species of Flavobacteriales has been implicated in infant meningitis, and where are they commonly found?

Flavobacterium meningosepticum has been implicated in infant meningitis. Flavobacteria, in general, are commonly found in aquatic habitats, both freshwater and marine, as well as in foods and food-processing plants.

Explain the characteristics of psychrophilic or psychrotolerant Flavobacteriales and their significance.

Psychrophilic or psychrotolerant Flavobacteriales are bacteria that thrive in cold environments. These organisms have adaptations to survive and grow at low temperatures, such as lipid membranes that remain fluid at cold temperatures. They play a crucial role in nutrient cycling in cold ecosystems and are important in food spoilage as well as biodegradation of organic matter in cold environments. While not pathogenic, they can contribute to food spoilage.

What distinguishes Sphingobacteriales from Flavobacteriales in terms of polysaccharide degradation?

Sphingobacteriales generally degrade a greater breadth of complex polysaccharides than Flavobacteriales, resembling Cytophagales in this aspect. The genus Flexibacter is typical of Sphingobacteriales.

Describe the characteristics of Flexibacter, a representative of Sphingobacteriales.

Flexibacter species require complex media for growth, lack cellulose degradation ability, and exhibit changes in cell morphology from long, gliding filaments to short, nonmotile rods. They are pigmented due to carotenoids or flexirubins and commonly reside in soil and freshwaters without identified pathogenicity.

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