Attachment to Autoclaved Soil of Bacterial Cells from Pure Cultures of Soil Isolates

Abstract

Pure cultures of Arthrobacter globiformis and four fresh soil isolates were incubated individually in autoclaved soil, in both the presence and absence of glucose. These bacteria grew in the soil and, except for A. globiformis, eventually attached firmly to the soil solids. Firmly attached cells were defined as those which could not be separated from the soil solids by blending combined with a series of low-speed centrifugal washings. The attachment attained by the soil isolates appeared to duplicate that of the overall bacterial population that resides naturally in unaltered, unamended soil. Cell attachment in the autoclaved-soil system was accelerated slightly by glucose, but, except for one soil isolate, several months of incubation were still required before firm attachment was complete. Electron microscopy indicated that all attached cells produced extracellular polysaccharide slimes in the autoclaved soil and that these materials appeared to connect the cells to surrounding pieces of soil debris. The actual role of polysaccharides in attachment was not clear, however, because at least one of these organisms possessed extracellular slime during the long period in which it had not yet attached to the soil.

Myceloid growth of Arthrobacter globiformis and other Arthrobacter species

“…1. The effective level of residual manganese was calculated to be approxiimately 1 in the metal salts added to the medium. In this case, the coccoid cells added as inoculum elongated to give long filaments that demonstrated rudimentary branching ( Fig.…”

“…plated on soil extract agar. The other isolate came from soil that had been incubated 1 week with the nicotine salts medium of Casida and Rosenfield (4). Streaking was on nicotine agar, and blue colonies were selected.…”

“…This entire process was repeated five times, except that the last addition of 8-hydroxyquinoline was allowed to stand overnight before four sequential extractions were performed with 10-ml portions of CHC13. The extracted basal solution or water was then stored in acid-washed polypropylene flasks (Kimble Products, Toledo, Ohio) at 5°C for no longer than 1 week. The metal cation salts to be added to extracted basal solution were made up as individual stock solutions with extracted water.…”

“…Both types of preparations were photographed, and measurements of cell size were made on the photomicrographs. Thin sections of bacterial cells were prepared and observed by transmission electron microscopy as described by Balkwill and Casida (1).…”

Differences in dynamics between indigenous and inoculated Sphingomonas paucimobilis strain SS86 in soils

“…Formation of biopolymers, such as extracellular polysaccharides, is also a considerable property specific to the indigenous SS86. With the biopolymer, bacteria could obtain enhanced tolerance to desiccation [30], and could attach to the surface of soil components [31,32], which might ensure this tolerance against protozoan predation [30] and transportation with percolating water.…”