title: Bioaugmentation with a Bacillus sp. to reduce the phytoavailable Cd of an agricultural soil: comparison of free and immobilized microbial inocula.
abstract: In order to reduce the cadmium potentially available for plants, soil bioaugmentation was performed by using a Bacillus sp. In a pot experimentation, sterilized and non-sterilized soils were inoculated using free or immobilized cells entrapped in alginate beads. This test was carried out with different inoculum sizes (2 x 10(10) and 2 x 10(11)CFU kg(-1) dw of soil) and alginate bead compositions (10 and 15 g of both alginate and CaCl(2) l(-1)). Then, the soil pots were incubated at 20 degrees C and the soil humidity was kept at a level of 20%. After 3 weeks of a batch incubation, the potentially phytoavailable Cd was reduced up to a factor of 14. The bioaugmentation resulted in the soil colonization by Bacillus sp. thanks to an increase of the cell concentration up to 1.8 log units. However, in comparison to the cells being inoculated in a free mode, the immobilization of the cells did not significantly improve the survival of the cells in the soil. Although the resulting effect not being highly pronounced, the potentially phytoavailable Cd correlated with the cell concentration in a surprisingly positive way. What is more, the Bacillus concentrations in the soil were positively correlated with the inoculum, too.
authors.affiliation: Laboratoire Gestion des Risques et Environnement, Université de Haute-Alsace, Antenne de Colmar, BP 50568, 68 008 Colmar cedex, France.
authors.forename: Karine
authors.initials: K
authors.lastname: Jézéquel
authors.forename: Janice
authors.initials: J
authors.lastname: Perrin
authors.forename: Thierry
authors.initials: T
authors.lastname: Lebeau
mesh_terms: D000383:Agriculture; D000464:Alginates; D001407:Bacillus / Q000254:growth & development / Q000378:metabolism*; D001673:Biodegradation, Environmental; D002104:Cadmium / Q000032:analysis* / Q000378:metabolism; D015169:Colony Count, Microbial; D020723:Glucuronic Acid; D006603:Hexuronic Acids; D010944:Plants / Q000378:metabolism; D012988:Soil Microbiology; D012989:Soil Pollutants / Q000032:analysis* / Q000378:metabolism
chemical_list: D000464:Alginates; D006603:Hexuronic Acids; D012989:Soil Pollutants; D002104:Cadmium; D020723:Glucuronic Acid