ISSN:
1573-5036
Keywords:
Azospirillum
;
bacterial adsorption
;
rhizosphere bacteria
;
soil adsorption
;
soil-bacteria interaction
Source:
Springer Online Journal Archives 1860-2000
Topics:
Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
Notes:
Abstract Inoculation and incubation of wild type Azospirillum brasilense Cd (agg+) in pure quartz sand resulted in cell attachment to sand particles by a network made up of various sizes and shapes of fibrillar material. Inoculation of sand with an aggregate-deficient mutant of strain Cd (agg−) resulted in no detectable fibrillar formation. Initial attachment ratio between agg+ cells and agg− cells was 4:1. However, similar bacterial populations developed in the sand. Rinsing the sand, colonized by either strains, had a greater effect on agg−; decreasing adsorption from 8.1 to 1.4%. Prolonged rinsing entirely desorbed its cells from the sand. Long bacterial incubation in sand decreased the attachment ratio between agg+ and agg− from 3.4:1 to 2.9:1 and decreased desorption (by rinsing) from 10:1 to 6:1. Agitation increased bacterial population size (from 2 × 107 to 4 × 108 cfu g−1) and decreased the proportion of attachment of agg+ cells (from 29.2 to 9.8%). A decrease in attachment was being of higher magnitude in the non-aggregating mutant (from 5 to 0% adsorption). Protease treatment of sand colonized with either bacteria decreased attachement of agg+ (from 27.4 to 7.1%) and released proteinaceous compound(s) into the sand only in the agg+ strain. Addition of NaEDTA to sand before inoculation, decreased attachment of agg+ (from 24.2 to 14%) but had no effect on agg−. Addition of low amcunt of clay (montmorillonite) to sand significantly increased adsorption of agg− to the sand particles (from 8.8 to 98.3%). Survival period of agg+ cells in sand was slightly longer than that of agg− cells. It is proposed that bacterial fibrils are essential for anchoring of A. brasilense to sand.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00011014
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