Phosphate For Growth Research Articles

Using Microalga Scenedesmus quadricauda for the Improvement of Municipal Wastewater Quality

Microalgae culture is an interesting step in wastewater treatment since it provides a tertiary biotreatment while also producing potentially valuable biomass that may be used for a variety of applications. Microalgae cultures, with their ability to utilize inorganic nitrogen and phosphate for growth, provide an elegant solution to tertiary and quaternary treatments. Scenedesmus quadricauda culture was employed with three different doses, 2g/l, 1g/l, and 0.2g/l, to investigate the impacts of microalgae in wastewater. Standard procedures were used to measure samples for physicochemical parameters such as pH, EC, PO4, NO3, NO2, NH4 and BOD5 every third day for 21 days. Results showed that a higher dose of 2g.l-1 was the most effective for removing the highest rate of nutrients. It was confirmed by significant differences (p≤0.05) between all doses. Ammonium pass had the highest removal percentage of 97%, followed by NO3 with 95.7%, and BOD5 with a range of 90.3 to 93.5 %. Decreases in nutrients were accompanied by a rise in chlorophyll content, with the greatest biomass of 1.52 mg. l-1 on the 17th day of the experiment. The purpose of this paper is to provide an overview of the methods that microalgae use to bioremediate organic contaminants in aquatic ecosystems.

Single-cell imaging of phosphorus uptake shows that key harmful algae rely on different phosphorus sources for growth

Single-cell measurements of biochemical processes have advanced our understanding of cellular physiology in individual microbes and microbial populations. Due to methodological limitations, little is known about single-cell phosphorus (P) uptake and its importance for microbial growth within mixed field populations. Here, we developed a nanometer-scale secondary ion mass spectrometry (nanoSIMS)-based approach to quantify single-cell P uptake in combination with cellular CO2 and N2 fixation. Applying this approach during a harmful algal bloom (HAB), we found that the toxin-producer Nodularia almost exclusively used phosphate for growth at very low phosphate concentrations in the Baltic Sea. In contrast, the non-toxic Aphanizomenon acquired only 15% of its cellular P-demand from phosphate and ~85% from organic P. When phosphate concentrations were raised, Nodularia thrived indicating that this toxin-producer directly benefits from phosphate inputs. The phosphate availability in the Baltic Sea is projected to rise and therefore might foster more frequent and intense Nodularia blooms with a concomitant rise in the overall toxicity of HABs in the Baltic Sea. With a projected increase in HABs worldwide, the capability to use organic P may be a critical factor that not only determines the microbial community structure, but the overall harmfulness and associated costs of algal blooms.

Comparison of Microbial Phytase and Dicalcium Phosphate for Growth and Bone Mineralization of Pond-Raised Channel Catfish, Ictalurus punctatus

This study evaluated the use of microbial phytase as replacement for inorganic phosphorus supplement in diets for pond-raised channel catfish, Ictalurus punctatus. Channel catfish fingerlings (average weight: 23 g) were stocked into twelve 0.04-ha ponds at a rate of 18,525 fish/ha. Four ponds were used for each treatment. Fish were fed one of three experimental diets containing 250 or 500 FTU (phytase unit) phytase/kg, or 0.75% dicalcium phosphate once daily to satiation from May to October, 2000. No differences were observed in diet consumption, weight gain, feed conversion ratio, survival, or bone ash and phosphorus concentrations among fish fed different diets. Based on these results it appears that a phytase concentration of 250 FTU/kg diet applied post-pelleting can replace the dicalcium phosphate supplement in channel catfish diets without affecting fish growth and bone mineralization under pond culture conditions. We recommend that a phytase level of 500 FTU/kg diet be used and that the diet contain a total phosphorus level of 0.6% or above to ensure that adequate amount of phosphorus is available to channel catfish. Based on current prices of phytase and inorganic phosphorus sources, it is economical to use phytase in catfish diets.

Development of high-cell-density fermentation for heterologous interleukin 1\ production in Kluyveromyces lactis controlled by the PH05 promoter

The use of a phosphate organic form taken up by Kluyveromyces lactis removes repression of the PHO5 promoter and releases heterologous interleukin 1 beta synthesis while providing sufficient phosphate for growth. The oxidative metabolism of high-cell-density fed-batch and chemostat cultures was thus maintained under derepressed protein synthesis conditions. Interleukin 1 beta production was then growth-associated, an unusual mode of protein synthesis regulation under the control of the PHO5 promoter.

Targeted disruption of the Myxococcus xanthus orotidine 5'-monophosphate decarboxylase gene: effects on growth and fruiting-body development

The Myxococcus xanthus gene coding for orotidine 5'-monophosphate (OMP) decarboxylase (EC 4.1.1.23) was cloned. The M. xanthus uraA gene efficiently complemented an Escherichia coli OMP decarboxylase mutant, permitting it to grow in the absence of uracil. Electroporation of M. xanthus with a circular plasmid carrying a selectable uraA::kan gene disruption resulted in homologous recombination at the chromosomal uraA locus. Chromosomal integration of the gene disruption plasmid created heterozygous (uraA+/uraA::kan) tandem duplications. These tandem duplications were unstable and segregated auxotrophic uraA::kan daughters at frequencies of 2 x 10(-4) to 8 x 10(-4) per viable cell. Rare uraA::kan segregants were easily obtained by selecting for resistance to the toxic analog 5-fluoroorotic acid. Our experiments suggest that the cloned uraA gene could facilitate the use of gene duplications in the genetic analysis of M. xanthus development. The uraA mutants could utilize uracil, uridine, or uridine 5'-phosphate for growth, indicating that M. xanthus has pyrimidine salvage pathways. During multicellular development, uraA::kan gene disruption mutants sporulated to wild-type levels but formed smaller and more numerous aggregates than did their uraA+ parent, regardless of whether uracil was added to the medium. Pyrimidine deprivation of uraA mutants, under conditions that otherwise supported vegetative growth, failed to induce fruiting-body development or sporulation.

Metabolic and genetic aspects of the relationship between growth and tetracycline production in Streptomyces aureofaciens

A mutant of S. aureofaciens characterized by lower growth and higher tetracycline production than its parent strain is described. The mutant has a limited degree of temperature-sensitivity and shows a lower efficiency in the utilization of phosphate for growth and a higher cellular content of RNA. The data are in accordance with a possible mutation impairing some aminoacyl RNA synthetases. This kind of mutation might explain the lower growth in phosphate limited conditions and the higher content of RNA.

The occurrence of pyridoxamine phosphate in milk

SummaryThe presence of pyridoxamine phosphate in extracts of freeze-dried raw and evaporated milks has been demonstrated by separation and identification of the vitamin B6active compounds by chromatography and electrophoresis on paper. Its presence in the milk extracts is the cause of the higher values for vitamin B6activity measured withStreptococcus faecalisas compared with those obtained withStr. faeciumorSaccharomyces carlsbergensis. This is becauseStr. faecaliscan utilize the phosphate for growth as readily as free pyridoxamine, whereasStr. faeciumandS. carlsbergensiscannot. The mild acid treatment used for extracting the vitamin B6active compounds from the milk samples for microbiological assay was found to be insufficient to hydrolyse the pyridoxamine phosphate. Further treatment of the acid extracts with intestinal phosphatase released the pyridoxamine from its phosphate and increased the vitamin B6activity measured withS. carlsbergensisandStr.faeciumso that the total vitamin B6activities of the freeze-dried raw and evaporated milks measured microbiologiclly, were then in agreement with the values found in previous tests with chicks and rats.Pyridoxamine phosphate could only be detected in small amounts in a sample of fresh milk. The possibility that more of it was formed during the processing and storage of the freeze-dried samples is discussed.