Factors Influencing the Growth and Survival of Rhizobia in Humus and Soil CULTURES.II

Abstract

A study was made of several factors influencing the growth and survival of rhizobia in humus and soil cultures. Screw-capped glass jars were more satisfactory than the foil-lined cardboard cartons used commercially for packaging of seed inoculation cultures because contaminants were excluded and moisture retained more effectively. Refrigeration of the cultures reduced water losses and proved to be an excellent method of maintaining large numbers of living bacteria for a long time. The addition of sucrose to the humus cultures ordinarily produced large increases in numbers of rhizobia, as determined by plate counts, and the addition of various inorganic nutrients generally produced smaller increases. In general, any particular element stimulated growth only if the level of that element in the soil used as a base was below optimum. Nitrate and sucrose stimulated growth when either was used alone, but together they greatly depressed growth.

Some Factors Influencing the Growth and Survival of Root Nodule Bacteria in Peat Culture

“…Rhizobia grew and survived better in containers allowing free exchange of gas (Hedlin & Newton, 1948;van Schreven, Otzen & Lindenbergh, 1954). However, other workers have reported satisfactory survival in either screwcapped jars or sealed cans (Newbould, 1951; Spencer & Newton, 1953;Gunning & Jordan, 1954). When aeration was restricted, pure cultures grew better than contaminated cultures (Hedlin & Newton, 1948).…”

“…The influence of temperature has been studied by Spencer & Newton (1953) with cultures in screwcapped jars, by Gunning & Jordan (1954) using heated peat which may restrict growth (Roughley & Vincent, 1967), and by Waters & Date (cited by Vincent, 1958). Generally, low temperatures have restricted multiplication but improved survival during storage.…”

Soil science at the University of Alberta: a century of service to science and society

“…Newton devoted his career to nitrification studies, including effects of incorporated straw on N immobilization. Several of his students (Hedlin 1947;Spencer 1951;Thomas 1959) investigated symbiotic N fixation by Rhizobia sp. leading to development of a legume inoculant.…”

Oxygen Uptake by Rhizobia in Soil

“…However, rlmizobirt are unable t o utilize polysaccharides and similar compounds and must depend for a source of energy upon monoand disacchnrides, sugar alcohols, and other conspounds s% like nature. As part of a series of studies of the behavior of rhizobin in soil cultures (2,5), therefore, an attempt was made t o determine the relative amounts of nutrient materials made available to the rlnizsbia by the decompositiors of,plant residues in soil. FIG The co~sventional Warburg respironicter has bee11 widely used in the study of the rnetabolism of XTzizsb.kum species and other microorganisms.…”