Phosphate uptake kinetics byAcinetobacter isolates

Removal of phosphate by Staphylococcus aureus under aerobic and alternating anaerobic-aerobic conditions

Eutrophication of water bodies due to phosphate enrichment is an ecological problem. Phosphate is removed from wastewaters by enhanced biological phosphate removal worldwide by phosphate accumulating organism. In order to understand the process of treatment, the existing microbial community and its metabolism of phosphate removal are studied widely. This study focuses on the isolation of polyphosphate-accumulating bacteria from different environments and studying their phosphate removal capacity with different carbon supplements under varying culture conditions. The total heterotrophic bacterial population from the diverse environments showed the existence of phosphate-accumulating bacteria. Among them, Staphylococcus aureus removed 81% of phosphate in a polyphosphate-accumulating medium with storage of 93 mM polyphosphate internally. Among the different carbon sources provided, glucose induced a net specific growth rate of 0.816/d. S. aureus removed 70% of phosphate with a phosphate uptake rate of 6.29 mg PO₄/g cells and a growth yield of 0.2 g cells/g glucose consumed when 1 g/L glucose was provided. Furthermore, when 2 g/L glucose was provided, 78% of phosphate was removed with a phosphate uptake rate of 13.24 mg PO₄/g cells and a growth yield of 0.4 g cells/g glucose consumed under aerobic condition. S. aureus showed enhanced phosphate removal under aerobic condition in the presence of glucose.

Screening of Phosphorus-Accumulating Fungi and Their Potential for Phosphorus Removal from Waste Streams

While bacteria have been primarily studied for phosphorus (P) removal in wastewater treatment, fungi and their ability to accumulate intracellular polyphosphate are less investigated. P-accumulating fungal strains were screened from soybean plants and surrounding soil by flask cultivation with potato dextrose broth and KH2PO4 in this study. Mucor circinelloides was selected for its high efficiency in P removal efficiency and high cellular P content. Neisser staining and growth-curve analysis confirmed that M. circinelloides stored polyphosphate intracellularly by luxury phosphate uptake. The effect of culture medium compositions on P removal efficiency and cellular P content was also investigated. Monosaccharides (such as glucose and fructose) and organic nitrogen (N, such as urea, and peptone) promoted fungi growth and P accumulation. M. circinelloides also preferred organic phosphates. When glucose, urea, and phytic acid sodium salt were used as the carbon, N, and P source, respectively, the maximum utilization efficiency was 40.1% for P and 7.08% for cellular P content. In addition, the potential of M. circinelloides for P removal from waste streams was investigated. Compared with the non-inoculated control culture, inoculation with M. circinelloides improved the soluble P removal in treating wastewater centrate, screened manure, and digested manure.

Progress curve analysis for enzyme and microbial kinetic reactions using explicit solutions based on the Lambert W function

We present a simple method for estimating kinetic parameters from progress curve analysis of biologically catalyzed reactions that reduce to forms analogous to the Michaelis-Menten equation. Specifically, the Lambert W function is used to obtain explicit, closed-form solutions to differential rate expressions that describe the dynamics of substrate depletion. The explicit nature of the new solutions greatly simplifies nonlinear estimation of the kinetic parameters since numerical techniques such as the Runge-Kutta and Newton-Raphson methods used to solve the differential and integral forms of the kinetic equations, respectively, are replaced with a simple algebraic expression. The applicability of this approach for estimating Vmax and Km in the Michaelis-Menten equation was verified using a combination of simulated and experimental progress curve data. For simulated data, final estimates of Vmax and Km were close to the actual values of 1 microM/h and 1 microM, respectively, while the standard errors for these parameter estimates were proportional to the error level in the simulated data sets. The method was also applied to hydrogen depletion experiments by mixed cultures of bacteria in activated sludge resulting in Vmax and Km estimates of 6.531 microM/h and 2.136 microM, respectively. The algebraic nature of this solution, coupled with its relatively high accuracy, makes it an attractive candidate for kinetic parameter estimation from progress curve data.

Recent advances in removing phosphorus from wastewater and its future use as fertilizer (1997-2003)

Large quantities of phosphate present in wastewater is one of the main causes of eutrophication that negatively affects many natural water bodies, both fresh water and marine. It is desirable that water treatment facilities remove phosphorus from the wastewater before they are returned to the environment. Total removal or at least a significant reduction of phosphorus is obligatory, if not always fulfilled, in most countries. This comprehensive review summarizes the current status in phosphorus-removal technologies from the most common approaches, like metal precipitation, constructed wetland systems, adsorption by various microorganisms either in a free state or immobilized in polysaccharide gels, to enhanced biological phosphorus removal using activated sludge systems, and several innovative engineering solutions. As chemical precipitation renders the precipitates difficult, if not impossible, to recycle in an economical industrial manner, biological removal opens opportunities for recovering most of the phosphorus and beneficial applications of the product. This review includes the options of struvite (ammonium-magnesium-phosphate) and hydroxyapatite formation and other feasible options using, the now largely regarded contaminant, phosphorus in wastewater, as a raw material for the fertilizer industry. Besides updating our knowledge, this review critically evaluates the advantage and difficulties behind each treatment and indicates some of the most relevant open questions for future research.

Nitrite inhibition of aerobic growth of Acinetobacter sp

Nitrite inhibition of Acinetobacter sp. growing under aerobic conditions was studied. Specific growth rates under non-limiting concentrations of acetate and dissolved oxygen averaged 0.62h(-1). Growth and phosphate uptake by Acinetobacter sp. were both inhibited by increasing nitrite concentrations. The median inhibitory concentration (IC50) of free nitrous acid (FNA) was 0.10 mg/L and the IC10 of FNA was 0.05 mg/L. Removing nitrite from cultures reversed the inhibitory effect. Comparison of the IC10 of FNA for Acinetobacter sp. to inhibitory concentrations for other wastewater heterotrophic bacteria suggests that Acinetobacter sp. are relatively sensitive to this compound.