RT Journal Article SR Electronic(1) A1 Montgomery, Diana M. A1 Dean, Alastair C. R. A1 Wiffen, Paul A1 Macaskie, Lynne E.YR 1995 T1 Phosphatase production and activity in Citrobacter freundii and a naturally occurring, heavy-metal-accumulating Citrobacter sp. JF Microbiology, VO 141 IS 10 SP 2433 OP 2441 DO https://doi.org/10.1099/13500872-141-10-2433 PB Microbiology Society, SN 1465-2080, AB Summary: The ability of a naturally occurring Citrobacter sp. to accumulate cadmium has been attributed to cellular precipitation of CdHPO4, utilizing HPO2- 4 liberated via the activity of an overproduced, Cd-resistant acid-type phosphatase. Phosphatase production and heavy metal accumulation by batch cultures of this strain (N14) and a phosphatase-deficient mutant were compared with two reference strains of Citrobacter freundii. Only strain N14 expressed a high level of acid phosphatase and accumulated lanthanum and uranyl ion enzymically. Acid phosphatase is regulated via carbon-starvation; although the C. freundii strains overexpressed phosphatase activity in carbon-limiting continuous culture, this was approximately 20-fold less than the activity of strain N14 grown similarly. Citrobacter strain N14 was originally isolated from a metal-contaminated soil environment; phosphatase overproduction and metal accumulation were postulated as a detoxification mechanism. However, application of Cd-stress, and enrichment for Cd-resistant C. freundii (‘training’), reduced the phosphatase activity of this organism by about 50% as compared to Cd-unstressed cultures. The acid phosphatase of C. freundii and Citrobacter N14 had a similar pattern of resistance to some diagnostic reagents. The enzyme of the latter is similar to the PhoN acid phosphatase of Salmonella typhimurium described by other workers; the results are discussed with respect to the known phosphatases of the enterobacteria., UL https://www.microbiologyresearch.org/content/journal/micro/10.1099/13500872-141-10-2433