Enumeration of Free-Living Aerobic N 2 -Fixing H 2 -Oxidizing Bacteria by Using a Heterotrophic Semisolid Medium and Most-Probable-Number Technique

Enumeration of free-living aerobic n(2)-fixing h(2)-oxidizing bacteria by using a heterotrophic semisolid medium and most-probable-number technique.

A heterotrophic semisolid medium was used with two sensitive assay methods, C(2)H(2) reduction and O(2)-dependent tritium uptake, to determine nitrogenase and hydrogenase activities, respectively. Organisms known to be positive for both activities showed hydrogenase activity in both the presence and absence of 1% C(2)H(2), and thus, it was possible to test a single culture for both activities. ...

Nitrogen-fixing (acetylene redution) activity and population of aerobic heterotrophic nitrogen-fixing bacteria associated with wetland rice.

Nitrogen-fixing activity associated with different wetland rice varieties was measured at various growth stages by an in situ acetylene reduction method after the activities of blue-green algae (cyanobacteria) in the flood water and on the lower portion of the rice stem were eliminated. Nitrogen-fixing activities associated with rice varieties differed with plant growth stages. The activities i...

Tempo® Most Probable Number Technique for the Enumeration Yeasts and Moulds in Feed and Food Products

The large and diverse group of microscopic foodborne yeasts and moulds includes several hundred species. Both yeasts and moulds cause various degrees of deterioration and decomposition of food. They can invade and grow on virtually any type of food at any time, e.g. they invade field crops such as small grains, nuts, beans, tomatoes, and apples both in the field before harvesting and during sto...

Antarctic Soils Bacteria Isolated from Fuel-Contaminated Free-Living Heterotrophic Nitrogen-Fixing

Factors influencing detection and enumeration of Pseudomonas aeruginosa by most-probable-number and membrane filtration techniques.

Most-probable-number (MPN) and membrane filtration (mF) techniques were evaluated with respect to selectivity, sensitivity, and efficiency in recovering Pseudomonas aeruginosa strains in hospital fluids and extramural water environments. Known numbers of cells of a naturally occurring strain of P. aeruginosa maintained in distilled water or cells subcultured on Standard Methods agar were added ...