Hydrogenomonas eutropha cells harvested from semicontinuous autotrophic culture and washed free of substrate contain about 13% of nitrogen on a dry-solids basis. Biological value and digestibility of the bacterial nitrogen were determined in the rat by use of an abbreviated Mitchell-Thomas nitrogen balance technique and casein as the standard protein. Casein nitrogen was 99% digestible, and that of both whole boiled and sonically ruptured bacterial cells was 93%. Biological value of casein and the bacterial preparations was uniformly 77%. Amino acid composition of the bacteria, as in the case of casein, indicates a first limitation of sulfur-containing amino acids. These compositional features suggest that H. eutropha may be potentially valuable as a protein supplement in animal feeds.

Amino Acids↗

PubMed1969

Nutritional value of lipids in Hydrogenomonas eutropha as measured in the rat.

Hydrogenomonas eutropha is known to accumulate lipid, comprised largely of polymerized beta-hydroxybutyric acid, when maintained in nitrogen-deficient medium. This lipid was very poorly absorbed by mice from bacteria-containing diets, even though nitrogen absorption was adequate. The monomer, free beta-hydroxybutyric acid, was well absorbed from purified diet. Rats fed the monomer or butyric acid ate less food and grew more slowly than rats fed corn oil.

Animal Feed↗

PubMed1969

Effect of dried beans and silicone on intestinal hydrogen and methane production in man.

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Adult↗

PubMed1969

Intestinal hydrogen and methane of men fed space diet.

Intestinal bacteria form two gases, hydrogen (H2) and methane (CH4), that could constitute a fire hazard in a closed chamber. So H2 and CH4 pass from the anus but these gases are also transported by the blood to the lungs and removed to the atmosphere. Several factors affect gas formation: 1) amount and kind of fermentable substrate; 2) abundance, types, and location of microflora; and 3) psychic and somatic conditions that affect the gut. We evaluated the first factor by studying men fed different diets and have also recorded influences of uncontrollable factors. One group of 6 men ate Gemini-type diet (S) and another received a bland formula (F), for 42 days. Breath and rectal gases were analyzed during the first and final weeks. Flatus gases varied widely within dietary groups but much more gas was generated with diet S than with F. In the first 12-hour collection, subjects fed S passed 3 to 209 ml (ATAP) of rectal H2 (avg 52) and 24 to 156 ml (avg 69) from the lungs (assuming normal pulmonary ventilation). With F, these values were 0 to 3 ml (avg 1) and 6 to 36 ml (avg 20). Subjects were calmer during the second test. Gas production was lower with S than initially; F values were unchanged. Methane differed idiosyncratically, presumably due to differences in flora. Computed from 12-hour values, maximum potential daily H2 and CH4 are per man: for S, 730 ml and 382 ml; for F, 80 and 222 ml. Volumes would be larger at reduced spacecraft and suit pressures.

Bacteria↗

PubMed1969