Open AccessCadmium uptake and nitrogen fixing ability in heavy‐metal‐resistant laboratory and field strains of Rhizobium leguminosarum biovar trifolii
Author(s) -
Purchase Diane,
Miles Roger J,
Young Tom W.K
Publication year - 1997
Publication title -
fems microbiology ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.377
H-Index - 155
eISSN - 1574-6941
pISSN - 0168-6496
DOI - 10.1111/j.1574-6941.1997.tb00359.x
Subject(s) - biology , rhizobium leguminosarum , agar , cadmium , microbiology and biotechnology , nitrogen fixation , yeast extract , mannitol , agar plate , rhizobium , extracellular , botany , bacteria , rhizobiaceae , food science , fermentation , inoculation , horticulture , biochemistry , symbiosis , chemistry , genetics , organic chemistry
Rhizobium leguminosarum bv. trifolii produced mucoid colonies on yeast mannitol agar, but non‐mucoid colonies appeared with a frequency of 10 −7 on agar additionally containing 4 mM ZnCl 2 . Cells producing non‐mucoid colonies were also obtained from root nodules of white clover from experimental field plots treated with heavy‐metal‐contaminated sewage sludge. Compared to mucoid strains, non‐mucoid strains produced approximately half of the extracellular polysaccharide, two to three fold higher levels of intracellular carbohydrate and possessed larger intracellular inclusions. They also showed up to two‐fold times greater resistance to Cd 2+ , Cu 2+ , Ni 2+ and Zn 2+ . The total uptakes of Cd 2+ were similar between the laboratory strains and amongst the field strains. In non‐mucoid strains, Cd 2+ was not removed by washing in 0.1 M HNO 3 , suggesting Cd 2+ was bound intracellularly. All strains were effective in fixing nitrogen in white clover.