The Bacterial Flora of the Intestine of Ascaris suum and 5-Hydroxytryptamine Production

Abstract

Representative facultative anaerobes of the bacterial flora from the intestine of female Ascaris suum were isolated and identified. The number of bacteria in the intestine was approximately 4 X 10(9) per g wet weight of intestine. Seventeen of 19 of the isolated colonies were found to secrete 5-hydroxytryptamine in culture. Holding A. suum in an antibiotic-containing medium did not affect the levels of 5-hydroxytryptamine in the worm, which were 231 +/- 14 ng/g in antibiotic-media as compared to 250 +/- 16 ng/g in control media. This implied that the bacteria may not be contributing to the level of 5-hydroxytryptamine in the tissues of A. suum.

Reciprocal Interactions between Nematodes and Their Microbial Environments

“…Earlier studies demonstrated nematode-associated bacterial communities in A. suum (Hsu et al, 1986; Shahkolahi and Donahue, 1993). One study aimed at identifying the source of serotonin present in nematodes, which generally lack the enzymes necessary for de novo synthesis of serotonin from tryptophan, revealed 4 × 10 9 bacteria per gram of nematode intestine (Hsu et al, 1986).…”

“…One study aimed at identifying the source of serotonin present in nematodes, which generally lack the enzymes necessary for de novo synthesis of serotonin from tryptophan, revealed 4 × 10 9 bacteria per gram of nematode intestine (Hsu et al, 1986). In addition to E. coli, Enterobacter, Klebsiella, Acinetobacter, Citrobacter, Pseudomonas, Aeromonas , and Shigella were identified among gram-negatives while Staphylococcus, Streptococcus, Corynebacterium , and Bacillus were identified amongst gram-positive organisms.…”

Symbiotic bacteria of helminths: what role may they play in ecosystems under anthropogenic stress?

“…Many of the bacteria described from helminths, particularly those worms residing within the intestinal tract, are ectosymbiotic on the parasites' tegumental surface. In particular, intestinal helminths are known to host a rich bacterial community (Hsu et al, 1986;Krecek et al, 1987;Poddubnaya & Izvekova, 2005;Korneva, 2008;Hayes et al, 2010), and it would appear that the digestive tract is a major site for interactions between bacteria and these parasites. Nevertheless, it remains to be determined if symbionts occur in all stages of the life cycle, and the exact mechanisms (vertical, horizontal or mixed transmission) by which the helminths acquire their bacteria.…”

“…This intestinal nematode of endotherms has a diverse bacterial community within its own guts and many of these bacteria secrete the hormone serotonin, which is considered to stimulate glycogen metabolism (Hsu et al, 1986). This intestinal nematode of endotherms has a diverse bacterial community within its own guts and many of these bacteria secrete the hormone serotonin, which is considered to stimulate glycogen metabolism (Hsu et al, 1986).…”

“…This intestinal nematode of endotherms has a diverse bacterial community within its own guts and many of these bacteria secrete the hormone serotonin, which is considered to stimulate glycogen metabolism (Hsu et al, 1986). This monoamine, like serotonin, is associated with stimulating glycogenolysis (Brownlee et al, 1994) and in bacterial-free conditions significantly lower concentrations are found in parasite tissues (Philips et al, 1975;Hsu et al, 1986). It is possible these bacteria may also be providing substantial amounts of supplementary histamine for the nematode.…”