Yaacov OkonStephan L. AlbrechtBurris, R.H.2014-09-052014-09-051977Appl. Environ. Microbiol. 1977, Vol.33, p.85-87http://hdl.handle.net/123456789/5378Methods are described for growing Spirillum lipoferum in quantities sufficient to serve as inoculant in field trials of its associative N2-fixing ability with higher plants and as a source of cells for the preparation of nitrogenase, cytochromes, respiratory enzymes, etc. A heavy inoculum ot'S. lipoferum grown on NH4+ was transferred to a medium of minimal nitrogen content, and initial rapid growth at the expense of residual combined nitrogen was replaced later by slower growth on N,. Conversion to N; fixation was prompt upon exhaustion of fixed nitrogen; growth on N: was most rapid at a pO2 of 0,005 to 0.007 atm. Numbers of 5. lipoferum can be estimated by diluting soil, crushed roots, or other material, and inoculating diluted samples into a stagnant semisolid medium. Development of a characteristic subsurface layer of organisms and demonstration the these organisms can reduce C2H2 are presumptive evidence that they are S. lipoferum. With most-probable-number tables the observations can be converted to numbers of S. lipoferum in the samples. The rnost-probable-number method indicated that numbers of S. lipoferum may increase 100-fold or more in roots of maize removed from the plant and incubated for 24 h at 30°C at a pO2 initially adjusted to 0.01 atm.enArticle