Respiration Studies on Chlorella. I. Growth Experiments With Acid Intermediates

Abstract

IntroductionThe study of carbohydrate metabolism has received considerable attention in the animal domain. It has been assumed by many that carbohydrate metabolism in higher plants follows a similar path. Many investigators have contributed toward the elucidation of this assumption but the final goal has not yet been reached. The literature on the subject has been ably surveyed by VICKERY et al. (19), PUCHER et al. (11), and SIDERIS et al. (16) and will not be reviewed in detail in the present paper.The reactions occurring during the metabolism of carbohydrates are separated into two main schemes-one taking place under anaerobic, the other under aerobic conditions. The problems having received the most attention are largely concerned with anaerobic processes such as the fermentation of sugar to ethyl alcohol and the formation of lactic acid. The reactions leading to the complete oxidation of carbohydrates under aerobic conditions (i.e. respiration) are not as well understood.The object of the present investigation is to study the possible steps involved in the respiratory mechanism of plant tissues inasmuch as they are connected with the aerobic path of carbohydrates, by determining the extent to which some of the metabolic intermediates known for animal tissues fit into the plant domain.The program of research was planned to include several parts, the first being the study of the growth of chlorella when supplied with organic acids known to enter in the path of aerobic carbohydrate metabolism in animal tissues. Other portions are concerned with the effects of organic acids on respiration and the study of the action of various enzymes and enzyme inhibitors. These will be reported in subsequent publications. Materials and methodsMATERIALS.-The strain of chlorella used was originally isolated from soil by WANN (20) and has been maintained in pure culture in the Plant Physiology laboratory at Cornell University. According to CLARK (2), the species has not been described taxonomically.The chlorella used were all derived from a single cell obtained by plating out a suspension of cells at the beginning of the investigation. The Stock culture vessels were inoculated with a transfer loop and the organic acid cultures were inoculated with pipettes. The pipettes used for inoculation were sterilized in a hot air oven at 160°C to two hours. A small wad of cotton was inserted in the mouth end before sterilization.The flasks were then placed in the insulated thermostated chamber as described by MANDELS (8) and were automatically shaken for five minutes every hour. The light intensity applied for stock cultures was about 500 foot candles. On the other hand, the organic acid cultures were kept in the dark. For this purpose, the insulated chamber was protected from light by four layers of black cotton cloth. In both cases, the temperature of the chamber was adjusted to 280 C ± .5°.In preparing the inoculum for organic acid cultures, a known amount of cells was needed to permit an accurate measurement of growth. To free the...

Influence of pH On 2,4-Dichlorophenoxyacetic and Acetic Acid Activity in Chlorella.

“…oxidase (4,9), peroxidase (2), catalase (2,3,13), and phosphatase (8) activities in preparations-of various corn tissues. In most cases, however, only one stage of development has been considered.…”

“…Assimilation of acetate in plants has been abundantly demonstrated (1,7,9,10,11,12,13,23,24). None of these studies on the respiration of acetate related the activity to concentration of substrate.…”

“…Eny (9,10) showed that citric was one of the least effective of the organic acids tried for promoting growth or altering respiration of Chlorella.…”

Respiration Studies on Chlorella. Ii. Influence of Various Organic Acids on Gas Exchange

“…In a previous paper (9), the results of growth experiments were reported and there was some evidence of utilization of the acid intermediates for growth in the dark by chlorella.…”

Influence of Glucose & Light on Pyruvate Metabolism by Starved Cells of Chlorella elipsoida

“…If the rate of uptake of pyruvate from the medium is limited by its ability to support synthetic reactions, then the addition of either glucose or light partially overcomes the deficiency (22). Indeed the inability of pyruvate to support the assimilation of NH3 (10) or growth (6) indicates that the acids of the TCA cycle alone cannot promote the synthesis of proteins. In order to define the factor linmiting, the utilization of 1 Received Oct. 2,1961.°T his work was supported by the Alexander von Humboldt Stiftung, Germany.…”