Two strains of hydrogen‐oxidizing bacteria were used: Hydrogenomonas eutropha strain H16 and strain 11/x. The former is a gram‐negative flagellated rod and has been relatively well known with respect to its morphological, physiological, and biochemical properties. The latter is a gram‐positive, non spore‐forming, motile small rod the definite classification of which is unknown as yet.
Both strains were grown chemolithotrophically in submerged culture with a limited nitrogen‐source and supplied with a gas mixture of H2, O2, and CO2. The lipid composition of the bacteria was determined at the end of the exponential phase (I), at the storage phase (II), and after reutilization of storage material (III).
Along with the accumulation of poly(3‐hydroxybutyric acid) as the major storage material in strain H16 the amount of other lipids was shown to increase 1.8‐fold at phase II and to decrease at phase III. There is little or no change in the lipid pattern in various growth phases. It is suggested that the 1.8‐fold increase of the latter lipids during phase II is due to the synthesis of membrane lipids that are required for the formation of membranes surrounding the intra‐cellular granules of accumulating poly(3‐hydroxybutyric acid).
In strain 11/x the amount of lipids increases 7 times along with an equal increase of carbohydrates at phase II. The majority of accumulated lipids consists of triglycerides free of significant amounts of unusual acyl group. It is suggested that there is a true storage of triglycerides that are reutilized during phase III.
The lipid pattern of strain H16 is characterized by a high proportion of “strongly bound lipids” that consist predominantly of phospholipids. Characteristic lipid components are phosphatidylethanolamine, phosphatidylglycerol, and diphosphatidylglycerol, while coenzyme Q8 (0.41 μmol/g bacterial dry weight) has been found among the neutral lipids. A C17 cyclopropane acid (probably cis‐9,10‐methylene hexadecanoic acid) is present in all saponifiable lipids.
The lipid pattern of strain 11/x is characterized by a high proportion of “loosely bound lipids” that consist predominantly of neutral lipids, particularly of triglycerides. Among the polar lipids, diphosphatidylglycerol and phosphoinositides are most abundant, and several unknown phospholipids are also present. No cyclopropane fatty acid has been found. The possible use of strain 11/x as a source of nutritional fat is discussed.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.