Kinetics of growth and phosphate uptake in pure culture studies of Acinetobacter species

Abstract

Acinetobacter has been found to be the major species responsible for mediating biological phosphate removal. The growth kinetics and phosphate uptake were investigated for an isolated Acinetobacter strain growing in a defined medium. The phosphate uptake is dependent on growth rate, temperature, and pH. Polyphosphate granules occurred in a balanced growth stage. The maximum phosphorus content in cells was 4.8% at the dilution rate of 12 day(-1). The specific phosphate uptake rate was found to be a quadratic polynomial function of the dilution rate. Increased calcium (up to 36 mg/L) and magnesium (up to 15 mg/L), and the addition of yeast extract (100 mg/L), primary effluent (20%), and fluoride (10 mg/L) did not affect phosphate uptake. Anaerobic conditioning (N(2) stripping), low pH (CO(2) stripping), and addition of sodium acetate under anaerobic conditions failed to stimulate immediate phosphate release. Nevertheless, After 21-24 h, the phosphate release was ca. 3, 5, and 15 mg P/g cell, respectively, for N(2) purging, the addition of acetate, and CO(2) purging. For two-stage completely stirred reactor operation, there was negligible phosphate overplus at the second reactor when phosphate was added, when the first reactor was subjected to phosphate limitation. When both phosphate and carbon limited the growth in the first reactor, there was slight phosphate accumulation under endogenous respiration conditions in the second reactor.

Phosphate uptake kinetics byAcinetobacter isolates

“…The max values of most of our Acinetobacter isolates (grown at 30°C) were a little lower than those reported for acinetobacters isolated in municipal sludge [0.42 and 0.83 h −1 in ethanol and acetate at 25°C (Hao and Chang, 1987) Note: Phosphate uptake rates (v) at initial phosphate concentrations (P 0 ) of 2, 5 and 8 mg P L −1 , maximum uptake rate of phosphate (V max ), maximum specific growth rate ( max ), half-saturation constant (K s ), and coefficient (W). Coefficient W gives the amount of biomass needed to take up one phosphate unit and coefficient b relates cell density to dry mass (DM).…”

Influence of environmental parameters on polyphosphate accumulation inAcinetobacter sp.

“…This agrees with temperature optima for Acinetobacter sp. strains isolated from soil, sediments and activated sludge reported by other authors (Abbot et al 1973;Fuhs and Chen 1975;Du Preez 1978;Hao & Chang 1987). Growth is possible between a pH of 4.8 and 9.5, but growth on acetate is completely inhibited at a pH lower than 6 (Fig.…”

“…lb and 2b). Probably the effect of the growth rate on polyphosphate accumulation shows the same strain specificity, since Hao & Chang (1987) found an increase of polyphosphate accumulation with increasing growth rates of their Acinetobacter sp., which is contrary to the effect found in Acinetobacter strain 210A. From a fundamental point of view the differences between the strains are confusing, but from a practical point of view this means that biological phosphate removal from wastewater may be possible under divergent conditions, and is always based on Acinetobacter strains that are best adapted to the prevailing conditions.…”

Polyphosphate-dependent enzymes in some coryneform bacteria isolated from sewage sludge

“…They were cultivated aerobically on nutrient agar (Difco) at 25°C. For studying enzyme activities, cells were grown in a modified medium previously reported [11] with 500 mg 1-1 yeast extract.…”