Cytoplasmic glycogen inclusions in cells of anaerobic gram-negative rumen bacteria

Abstract

Megasphaera elsdenii, an anaerobic rumen bacterium, produced intracellular polysaccharide granules varying in size from 0.05 to 0.15 μm during growth in batch culture. This polysaccharide material was purified and was found to contain D-glucose as the only reducing sugar. The polyglucose polymer was highly opalescent in aqueous solution and formed a strong reddish-brown iodine complex with a maximum absorbance at 493 nm. Its infrared spectrum had characteristic absorption bands at 8.70, 9.25, and 9.75 μm and was identical with that of the glycogen of enteric bacteria and beef liver. When these polysaccharide granules were observed with an electron microscope, they resembled the glycogen granules produced by Arthrobacter globiformis and Escherichia coli. These properties indicate that the polysaccharide was a type of glycogen. The yield of crude glycogen was 16.82% of the dry weight of late log-phase cells (14-h).The lysis of cells of M. elsdenii and other rumen bacteria that store polysaccharide granules inside the cells, in the rumen of cows fed a feed of fine-particle size (344 μm, geometric mean particle size) and high-energy content, may contribute to the high-carbohydrate level and high viscosity of the cell-free rumen fluid of these cows. Cows fed a coarse feed (519 μm, geometric mean particle size) of the same composition have rumens that contain few bacteria with polysaccharide granules. The cell-free rumen fluid of these cows has low viscosity and low-carbohydrate content.

Demonstration of extracellular material at the surface of pathogenic T. pallidum cells.

“…This observation is consistent with the same finding for virulent and avirulent treponemes. However, it has been suggested that an extracellular layer may stabilize the bacterial cell-associated enzymes (Cheng and Costerton, 1973;Costerton, Ingram, and Cheng 1974) or may serve as a protective adaptation (Costerton, Damgaard, and Cheng, 1974) against large molecules, enzymes, and antibodies. It has been shown (Jones and others, 1968) that washing freshly harvested virulent treponemes once in buffer renders the surface of the cell susceptible to the action of lytic agents.…”

Effects of varying the degree of synchrony of energy and nitrogen release in the rumen on the synthesis of microbial protein in lactating dairy cows consuming a diet of grass silage and a cereal-based concentrate

“…Presumably, the apparent lack of effect of the degree of synchrony on MPS derives from the ability of rumen bacteria to buffer themselves against the effects of uctuating supplies of available energy and nitrogen by synthesizing intracellular storage polysaccharide when fermentable carbohydrate is in relative excess, 4 to be used as a source of ATP later in the feeding cycle when fermentable carbohydrate is in short supply. 5 However, the capacity of ruminal bacteria for storage of intracellular polysaccharide must be limited.…”

Vibrio cholerae as a predator: lessons from evolutionary principles

“…Intraguild predation differs from classical predation because it reduces competition and also differs from traditional competition because the predator directly benefits energetically from the demise of organisms that compete for the same resource pool (Polis et al, 1989). The potential benefits of intraguild predation in intestinal colonization are evidenced by the observation that several bacterial species (Cheng et al, 1973) including Escherichia coli (Holme and Cedergren, 1961) and V. cholerae (Bourassa and Camilli, 2009) store glycogen in cytoplasmic inclusions during their tenure in the host. In addition to removing competitors from the colonization niche, predation would provide immediate energetic benefits from lysed bacteria to predators like V. cholerae upon entry into and before exiting the human host.…”