Carbon Nutrition and Metabolism of Polytomella caeca*

Abstract

SYNOPSIS. Polytomella caeca utilizes as sole carbon sources in chemically defined media: acetate, propionate, butyrate, valerate, pyruvate, succinate, ethyl, butyl, amyl, and hexyl alcohols. Glyceraldehyde and α‐ketoglutarate sustain very small populations. Caproate, caprylate, fumarate, malate, propyl, heptyl, and octyl alcohols and the iso‐compounds iso‐butyrate, iso‐butyl and iso‐hexyl alcohols are inadequate. Acetate is not assimilated <pH 5.0, propionate and butyrate <pH 6.0, and valerate <pH 7.0. Optimum for utilization of succinate is pH 3.0, for pyruvate pH 4.0, utilized also at pH 2.0 Fatty acids are utilized dissociated; succinate and pyruvate are utilized undissociated. Alcohols are assimilated throughout pH 4.0–7.4, except hexanol at pH 7.4. Alcohol availability is proportional to molecular length‐1. pH after growth of fatty acid media is 8.4 ± 0.4; stable in pH 2.0 pyruvate and pH 3.0 succinate media; 3.5 ± 0.3 in alcohol media with initial pH <6.0. Longer alcohols cause less pH decrease during growth. Acetate concentrations <0.2% do not support maximum populations; concentrations of 0.2–1.0% do. pH after growth increases in these media to pH 8.5 with maximum populations. Malate, fumarate, α‐ketoglutarate, and lactate seem not to penetrate the cell, but are metabolized by homogenates. Methylene blue reduction by homogenates indicates the presence of lactic, malic, succinic and α‐ketoglutaric dehydrogenases, fumarase and glutamic transaminase. Extracts contain Embden‐Meyerhof phosphate esters, ATP, and ADP.

Polytomella spp. growth on ethananol

“…All the physiological studies carried out on the algae of the genus Polytomella (see above) [8–10] indicate that these algae can cope with a wide variety of environmental conditions and therefore make Polytomella useful to investigate the mechanisms used by eukaryotes to adapt to their environment.…”

“…Earlier studies on Polytomella caeca have shown that this alga can grow on different carbon sources, including organic acids and alcohols of different chain length [8,9]. Depending on the carbon source and culture media, P. caeca growth can take place in a pH range of 1.4 to pH 9.6 [8,10].…”

The Effect of pH on the Availability of Acid Substrates for Polytomella caeca with Unexpected Activity by Succinate*

“…It has been reported that n-hexanoic and n-octanoic acids are not suitable carbon sources a t 0.1% ( 14). However, when their concentrations were reduced to 0.005./,, they, and n-heptylic acid, served as sole carbon sources.…”

Growth of Astasia longa on Ethanol. I. Effects of Ethanol on Generation Time, Population Density and Biochemical Profile

“…Astasia grown on ethanol reach population densities as much as [10][11][12][13][14][15] x higher than Astasia grown on acetate without a change in generation time. Even a t the same substrate molarities, Astasia invariably grows to a higher population density on ethanol than on acetate (Table 2 ) .…”