Phosphate Availability Research Articles

Screening of Phosphate Solubilizing Microorganisms Collected from Post Tin Mining: Potency for Future Mining Rehabilitation

Tin mining produced massive tailings which dispersed across the land in the post-tin mining area, transforming the landscape into a hilly or basin landscape. The dominated white silica sand in this area is prone to erosion from water and wind, resulting in soil nutrition deficiency, meanwhile, heavy metal levels were found to be elevated. This condition makes it difficult for organisms to live in such a degraded post-tin mining area. Phosphate solubilizing microorganisms (PSM) contribute to phosphate availability by dissolving both fertilizers and bounded P in soil. This study aimed to select indigenous PSM collected from post-tin mining areas. Zea mays spp., the tested plant, was grown in sterilized sand to avoid the possible nutrient content, particularly phosphate, in the soil. Rock phosphate Granufos (containing 20% P2O5) was applied in sterilized sand (v: v= 1:100) as the source of limited and insoluble P. The 17 indigenous PSM were tested by inoculating them into Zea mays spp. growing in sterilized sand. Non-inoculated Zea mays spp. were prepared as well as control. Inoculation of 17 indigenous PSM significantly had higher soil available phosphor in comparison to control. Two PSM of P7 and P15 significantly had higher shoot concentrations among treatments. The isolate of P5 had the highest shoot dry weight among treatments. Overall, all PSM inoculations improved growth performance due to increased soil available P and improved shoot P uptake. These findings suggest that indigenous PSM potentially fills nutrient deficiencies, particularly P as a macronutrient needed to rehabilitate degraded post-tin mining areas.

Response of cyanobacterial mats to ambient phosphate fluctuations: phosphorus cycling, polyphosphate accumulation and stoichiometric flexibility

Cyanobacterial mats inhabit a variety of aquatic habitats, including the most extreme environments on Earth. They can thrive in a wide range of phosphorus (P) levels and are thus important players for ecosystem primary production and P cycling at the sediment-water interface. Polyphosphate (polyP), the major microbial P storage molecule, is assigned a critical role in compensating for phosphate fluctuations in planktonic cyanobacteria, but little is known about potentially analogous mechanisms of mat-forming cyanobacteria. To investigate acclimation strategies of cyanobacterial mats to fluctuating phosphate concentrations, laboratory batch experiments were conducted, in which the cosmopolitan mat-forming, marine cyanobacterium Sodalinema stali was exposed to low dissolved P concentrations, followed by a P pulse. Our results show that the cyanobacteria dynamically adjusted cellular P content to ambient phosphate concentrations and that they had accumulated polyP during periods of high phosphate availability, which was subsequently recycled to sustain growth during phosphate scarcity. However, following the depletion of dispensable cellular P sources, including polyP, we observed a reallocation of P contained in DNA into polyP, accompanied by increasing alkaline phosphatase activity. This suggests a change of the metabolic focus from growth towards maintenance and the attempt to acquire organic P, which would be naturally contained in the sediment. P overplus uptake following a simulated P pulse further suggests that Sodalinema-dominated mats exhibit elaborated mechanisms to cope with severe P fluctuations to overcome unfavourable environmental conditions, and potentially modulate critical P fluxes in the aquatic cycle.

The implications of pulsating anode potential on the electrochemical recovery of phosphate as magnesium ammonium phosphate hexahydrate (struvite)

A sustainable approach to address the limited availability of rock phosphate is to electrochemically recover phosphorus (P) as struvite (magnesium ammonium phosphate hexahydrate, MgNH4PO4·6H2O) fertilizer. On Mg surfaces, however, magnesium hydroxide (Mg(OH)2) and/or struvite form resistive films that limit the release of divalent Mg ions and reduce struvite precipitation. The present work enhances struvite recovery through the application of a dynamic voltage with a sinusoidal waveform. Compared to a constant potential, our results demonstrated that a dynamic potential could enhance the rupture of the passivating film, and facilitate the release of Mg2+ from the metal anode, thereby overcoming passivation problems. Ammonium dihydrogen phosphate (NH4H2PO4, 10 mM) solutions at neutral pH were used as test solutions. A 160–192 % increase in magnesium release was observed versus constant voltage applications, resulting in a 1.3x increase in phosphate recovery. The scanning electron microscopy (SEM) and X-ray diffraction (XRD) characterizations indicated that the precipitate recovered contained struvite. An analysis of electrode surfaces using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) confirms a greater extent of passivating film breakdown under dynamic voltages.

The Utilization of Serratia marcescens to Increase Phosphate-Availability and Production of Cucumber in Alfisols

Serratia marcescens is a bacterium that can dissolve phosphate (P) in soil, increasing phosphate availability and allowing plants to use it to support plant growth. P-available in the soil is generally low, including in Alfisols, due to the formation of bonds with Al, Fe, Ca, Mg, and other cations, which is influenced by soil pH or clay mineral adsorption. Cucumber plants require adequate nutrients, including P nutrients, for optimal growth and production. The study was carried out in a greenhouse using a completely randomized design (CRD) with four treatments and five replications. The treatments were S. marcescens bacterial solution concentrations of P0 (0 ml); P1 (20 ml); and P2 (20 ml); P3 (60 ml) bacterial colony density: 33x109 cfu/ml. According to the findings of the study, S. marcescens inoculation had a significant effect on increasing soil pH by 6,16, P-total concentration of 41,62 mg/100g, P-available concentration of 28,39 ppm, P-tissue concentration shoot and root were 0,30% and 0,78%, respectively, and P-root uptake of 2,27 g/pot. Similarly, S. marcescens inoculation significantly affected the plant height of 138,72 cm, root volume of 43 ml, and root length of 59,92 cm compared to the control treatment.

Effect of planting and mowing cover crops as livestock feed on soil quality and pear production.

The increasing demand for animal-products has led to an increasing demand for livestock feed. Using cover crop as green manure in orchards is an effective measure to improve fruit yield and quality. However, the effect of mowing cover forage crops as livestock feed on soil quality and crop production is unclear. Therefore, a 4-year field experiment, which included two treatments, was conducted in pear orchards in Luniao County, China: natural grass (NG) and planting and mowing forage crop ryegrass as livestock feed (MF). Under MF treatment, most soil nutrient content, especially alkalihydrolysable N (AN), total phosphate (TP), available phosphate (AP), and microbial biomass phosphate (MBP), had decreased significantly (P<0.05), while β-D-glucosidase (BG, C-cycle enzyme) and soil C limitation at 10-20 cm depth and P limitation at subsoil (20-40 cm) was increased. In addition, the soil bacterial community component in topsoil (0-10 cm and 10-20 cm) and fungal community component in topsoil and subsoil were changed in the MF treatment. Network analysis showed that MF treatment had a lower edge number in topsoil but the community edge numbers increased from 12794 in NG to 13676 in MF in subsoil. The average weight degree of the three soil layers in MF treatment were reduced, but the modularity had increased than that in NG. For crop production, MF treatment was 1.39 times higher in pear yield and titratable acids (AC) reduced from 0.19% to 0.13% compared with NG. These changes were more associated with the indicators at the subsoil, especially for TP, AN, pH, and F-NMDS1 (non-metric multidimensional scaling (NMDS) axis 1 of fungi). These results provide data support for the feasibility of planting and mowing forage crops as livestock feed on orchards as well as a new idea for the integration of crop and livestock.

Increasing the Effectivity of Liquid Organic Fertilizer Enriched with Enterobacter cloacae to increase Phosphate Availability and Yield of Maize in Inceptisols

Inceptisols have problems of low availability of phosphorus. To improve soil phosphate and P fertilizer efficiency, it is necessary to develop fertilizer enriched with phosphate solubilizing bacteria (PSB). Liquid organic fertilizer enriched with PSB is expected to increase the efficiency in fertilization and improve the yield of sweet corn plants. This study was aimed to determine the effectiveness of liquid organic fertilizer enriched with Enterobacter cloacae on phosphate availability and increase the yield of maize (Zea mays L.) in Jatinangor Inceptisols. This experiment has been carried out at the Laboratory and Experimental Garden, Jatinangor, West Java, Indonesia with altitude of ±725 m above sea level. This experiment was conducted from March to September 2021. This experiment used Randomized Block Design (RBD) with three repetitions. The experiment showed the 10 L ha-1 of liquid organic fertilizer enriched with Enterobacter cloacae indigenous from Inceptisols enhanched the availability of phosphate (22,48 mg kg-1) and yield of maize (14,11 ton ha-1). Liquid organic fertilizer enriched with Enterobacter cloacae can reduced 50% of P fertilization and proposed as an alternative corn fertilizer and increased the yield of maize up to 55%, because Enterobacter cloacae to increase P solubility that caused soil available P increased.

Effects of acidic phosphorus-rich biochar from halophyte species on P availability and fractions in alkaline soils

Conditioning alkaline soil with acidic phosphorus-rich biochar might contribute to improving soil phosphorous (P) availability and waste utilization efficiency. In this study, acidic phosphorus-rich biochar was prepared using halophyte biochar (HBC) modified by H3PO4 (P-HBC) and H4P2O7 (PA-HBC). The P-containing groups and P fractions in the HBCs were characterized, and the effects of biochar on the P fractions in alkaline soil were examined with incubation experiments. The results showed that the pH of P-HBC (3.31) and PA-HBC (2.17) was significantly reduced compared with HBC, and the total P contents rose to 4.66 g·kg− 1 and 5.24 g·kg− 1, respectively. The spectral characterization confirmed the loading of P-containing and acidic functional groups in the HBCs after modification. The application of P-HBC and PA-HBC in alkaline soils decreased the soil pH and facilitated the transformation of stable P into active fractions. Overall, acidic phosphorus-rich biochar can be employed to increase P activity in alkaline soil.Graphical

Construction of Glucose-6-Phosphate Dehydrogenase Overexpression Strain of Schizochytrium sp. H016 to Improve Docosahexaenoic Acid Production.

Docosahexaenoic acid (DHA) is an important omega-3 polyunsaturated fatty acid (PUFA) that plays a critical physiological role in human health. Schizochytrium sp. is considered an excellent strain for DHA production, but the synthesis of DHA is limited by the availability of nicotinamide adenine dinucleotide phosphate (NADPH). In this study, the endogenous glucose-6-phosphate dehydrogenase (G6PD) gene was overexpressed in Schizochytrium sp. H016. Results demonstrated that G6PD overexpression increased the availability of NADPH, which ultimately altered the fatty acid profile, resulting in a 1.91-fold increase in DHA yield (8.81 g/L) and increased carbon flux by shifting it from carbohydrate and protein synthesis to lipid production. Thus, G6PD played a vital role in primary metabolism. In addition, G6PD significantly increased DHA content and lipid accumulation by 31.47% and 40.29%, respectively. The fed-batch fermentation experiment results showed that DHA production reached 17.01 g/L in the overexpressing G6PD strain. These results elucidated the beneficial effects of NADPH on the synthesis of PUFA in Schizochytrium sp. H016, which may be a potential target for metabolic engineering. Furthermore, this study provides a promising regulatory strategy for the large-scale production of DHA in Schizochytrium sp.

Rates of seafloor and continental weathering govern Phanerozoic marine phosphate levels

Phosphate is an essential macronutrient for all organisms with a key role in setting levels of marine primary productivity. Despite its importance for marine biogeochemical cycles and its role in shaping the evolution of marine organisms, the factors controlling phosphate bioavailability on geologic timescales remain poorly understood. Here we develop a statistical model of the coupled cycles of phosphate, carbon, oxygen and calcium to constrain the weathering-derived fluxes and seawater concentrations of phosphate through Phanerozoic time (541 million years ago to the present). Our model includes input parameters and time-dependent forcings derived from geologic and geochemical data. We find that the climate sensitivity of chemical weathering of the oceanic crust by low-temperature fluids exerts a first-order control on phosphate availability. Specifically, continental weathering is a source of the limiting nutrient phosphate, but seafloor weathering is considered to be a minor phosphate sink. Consequently, times in Earth history during which seafloor weathering constituted a large fraction of the total (seafloor + continental) weathering were also times during which phosphate influxes to and concentrations in the ocean were relatively low. Lower seawater phosphate levels during those times probably resulted in lower primary productivity and oceanic and atmospheric oxygen concentrations.

Effect of Raw and Composted Anaerobic Digestates from Sewage Sludge and Biowaste on Ryegrass Phosphorous Availability and Soil Carbon Management

Effect of Raw and Composted Anaerobic Digestates from Sewage Sludge and Biowaste on Ryegrass Phosphorous Availability and Soil Carbon Management

Altered microbial P cycling genes drive P availability in soil after afforestation

Soil Phosphorous (P) availability is a limiting factor for plant growth and regulates biological metabolism in plantation ecosystems. The effect of variations in soil microbial P cycling potential on the availability of soil P during succession in plantation ecosystems is unclear. In this study, a metagenomics approach was used to explore variations in the composition and diversity of microbial P genes along a 45-year recovery sequence of Robinia pseudoacacia on the Loess Plateau, as well soil properties were measured. Our results showed that the diversity of P cycling genes (inorganic P solubilization and organic P mineralization genes) increased significantly after afforestation, and the community composition showed clear differences. The gcd and ppx genes were dominant in inorganic P transformation, whereas phnM gene dominated the transformation of organic P. The abundance of genes involved in inorganic P solubilization and organic P mineralization was significantly positively correlated with P availability, particularly for phnM, gcd, ppx, and phnI genes, corresponding to the phyla Gemmatimonadetes, Acidobacteria, Bacteroidetes, and Planctomycetes. The critical drivers of the microbial main genes of soil P cycling were available P (AP) and total N (TN) in soil. Overall, these findings highlight afforestation-induced increases in microbial P cycling genes enhanced soil P availability. and help to better understand how microbial growth metabolism caused by vegetation restoration in ecologically fragile areas affects the soil P cycling.

Inositol polyphosphates-regulated polyubiquitination of PHR1 by NLA E3 ligase during phosphate starvation response in Arabidopsis.

Phosphate (Pi) availability is a major factor limiting plant growth and development. The key transcription factor controlling Pi-starvation response (PSR) is PHOSPHATE STARVATION RESPONSE 1 (PHR1) whose transcript levels do not change with changes in Pi levels. However, how PHR1 stability is regulated at the post-translational level is relatively unexplored in Arabidopsis thaliana. Inositol polyphosphates (InsPn) are important signal molecules that promote the association of stand-alone SPX domain proteins with PHR1 to regulate PSR. Here, we show that NITROGEN LIMITATION ADAPTATION (NLA) E3 ligase can associate with PHR1 through its conserved SPX domain and polyubiquitinate PHR1 invitro. The association with PHR1 and its ubiquitination is enhanced by InsP6 but not by InsP5. Analysis of InsPn-related mutants and an overexpression plant shows PHR1 levels are more stable in itpk4-1 and vih2-4/VIH1amiRNA but less stable in ITPK4 overexpression plants. Under Pi-deficient conditions, nla seedlings contain high PHR1 levels, display long root hair and accumulate anthocyanin in shoots phenocopying PHR1 overexpression plants. By contrast, NLA overexpression plants phenocopy phr1 whose phenotypes are opposite to those of nla. Our results suggest NLA functions as a negative regulator of Pi response by modulating PHR1 stability and the NLA/PHR1 association depends on InsPn levels.

SbPHO2, a conserved Pi starvation signalling gene, is involved in the regulation of the uptake of multiple nutrients in sorghum

Sorghum is one of the five most productive crops worldwide, but its yield is seriously limited by phosphate (Pi) availability. Although inorganic Pi signalling is well studied in Arabidopsis and rice, it remains largely unknown in sorghum. The sorghum sbpho2 mutant was identified, showing leaf necrosis and short roots. Map-based cloning identified SbPHO2 as Sobic.009G228100, an E2 conjugase gene that is a putative orthologue of the PHO2 genes in rice and Arabidopsis, which play important roles in Pi signalling. Pi starvation experiments and transformation of SbPHO2 into the rice ospho2 mutant further revealed that SbPHO2 is likely involved in Pi accumulation and root architecture alteration in sorghum. qRTPCR results showed that SbPHO2 was expressed in almost the entire plant, especially in the leaves. Furthermore, some typical Pi starvation-induced genes were induced in sbpho2 even under Pi-sufficient conditions, including Pi transporters, SPXs, phosphatases and lipid composition alteration-related genes. In addition to P accumulation in the shoots of sbpho2, concentrations of N, K, and other metal elements were also altered significantly in the sbpho2 plants. Nitrate uptake was also suppressed in the sbpho2 mutant. Consistent with this finding, the expression of several nitrate-, potassium- and other metal element-related genes was also altered in sbpho2. Furthermore, the results indicated that N-dependent control of the P starvation response is regulated via SbPHO2 in sorghum. Our results suggest that SbPHO2 participates in the regulation of the absorption of multiple nutrients, although PHO2 is a crucial and conserved component of Pi starvation signalling.

Are active and former floodplain soils of the lower middle Elbe similar? A study of soil characteristics and possible implications for forest restoration

The analyses of soil properties and processes under the consideration of the spatial complexity of floodplains is a key step in the preparation of floodplain restoration measures. In that context, we analyzed how hydrogeomorphology influences soil physicochemical properties and formation processes in hardwood floodplain forests at the local scale. Our analyses are based on, 44 mixed topsoil samples, 135 soil drillings (2.0 m depth) and 18 reference pits (1.6 m depth) distributed in 44 hardwood floodplain forests along 150 km of the middle Elbe River. We considered four hydrogeomorphic units (HGUs) along a lateral floodplain gradient. Two HGUs located in the active floodplain and defined by their morphology Active High (AH), and Active Low (AL), and two located in the former floodplain: seepage water influenced (FS), and disconnected from the river hydrology (FD). Our results indicate that the HGUs in the active floodplain benefit from a stronger connection to the river hydrology. Higher pHCaCl2 values in the active HGUs as well as expected higher total P contents due to river deposition result in increased phosphorous availability. Physicochemical parameters as lower pHCaCl2 and predominance of iron mottling found in the FD indicate increased P sorption, therefore lower Psol availability. However, HGUs in the former floodplain, particularly those disconnected from the river hydrology, are characterized by higher total carbon and nitrogen content. These results improve our understanding of the soil physicochemical dynamics and their interactions in the different hydrogeomorphic units, and could allow the evaluation of floodplain restoration measures based on soil nutrient distribution to increase the potential of restored forests to develop on the selected geographic setting.

Comparative Proteomic Analysis of Transcriptional and Regulatory Proteins Abundances in S. lividans and S. coelicolor Suggests a Link between Various Stresses and Antibiotic Production

Streptomyces coelicolor and Streptomyces lividans constitute model strains to study the regulation of antibiotics biosynthesis in Streptomyces species since these closely related strains possess the same pathways directing the biosynthesis of various antibiotics but only S. coelicolor produces them. To get a better understanding of the origin of the contrasted abilities of these strains to produce bioactive specialized metabolites, these strains were grown in conditions of phosphate limitation or proficiency and a comparative analysis of their transcriptional/regulatory proteins was carried out. The abundance of the vast majority of the 355 proteins detected greatly differed between these two strains and responded differently to phosphate availability. This study confirmed, consistently with previous studies, that S. coelicolor suffers from nitrogen stress. This stress likely triggers the degradation of the nitrogen-rich peptidoglycan cell wall in order to recycle nitrogen present in its constituents, resulting in cell wall stress. When an altered cell wall is unable to fulfill its osmo-protective function, the bacteria also suffer from osmotic stress. This study thus revealed that these three stresses are intimately linked in S. coelicolor. The aggravation of these stresses leading to an increase of antibiotic biosynthesis, the connection between these stresses, and antibiotic production are discussed.

Pilot-scale phosphate recovery from wastewater to create a fertiliser product: An integrated assessment of adsorbent performance and quality

Eutrophication and the predicted limited future availability of rock phosphate has triggered the increased development of phosphorus (P) recovery technologies, however, for remote regions, recovery solutions are still limited. Here, we report on a novel pilot-scale technology (FILTRAFLOTM-P reactor) to recover phosphate (PO43−) from wastewater effluent through a filtration/adsorption process in a rural setting. This unit employs enhanced gravitational filtration through adsorption media (here, a novel KOH deacetylated crab carapace based chitosan-calcite material (CCM)) with continuous self-backwashing. Trials were designed to assess how the FILTRAFLOTM-P unit would operate under ‘real’ conditions (both at low and high PO43− levels), and to ascertain the effectiveness of the adsorbent to recover phosphate from final effluent. High removal was achieved at low phosphate concentrations, bringing the residual effluent PO43− level below 1 mg/L (EU limit for sensitive water bodies), while phosphate was efficiently harvested (at more than 50%) at higher PO43− levels. Surface microprecipitation and inner-sphere complexation were postulated as the main PO43− adsorption mechanisms through XRD, XPS and EDX elemental mapping. Further, a quality assessment of the P-enriched CCM (which could be used as a potential soil amendment) was undertaken to consider elemental composition, microbiological assessment and quantification of organic micropollutants. Quality analysis indicated ∼2.5% P2O5 present, trace levels (well below legislative limits) of heavy metals and extremely low levels of organic pollutants (e.g., PCBs, pharmaceuticals). No detectable levels of target bacterial pathogens were observed. Pot trials showed that ryegrass cultivated with the addition of the CCM adsorbent achieved higher plant dry matter and P concentration when compared to unfertilised controls, with a slow-release kinetic pattern. This study showed that CCM used with the FILTRAFLOTM-P pilot reactor has high potential to recover phosphate from effluents and encourage resource recovery via bio-based management of waste.

Response of soil nutrients retention and rice growth to biochar in straw returning paddy fields

Applying straw to agricultural production to improve soil productivity and crop yields is significant. However, the straw-only application is possibly not a practical choice for achieving environmental protection and high yield. This study evaluated the applicability of straw combined with biochar to the paddy field. Two-year pot experiments were conducted to examine the effect of straw combined with different proportions (0, 5, 20, 40 t ha-1) of biochar on soil nitrogen retention, phosphorous availability, rice yield, and physiological parameters. Five treatments were included: control (CK), 7 t ha−1 straw + 0 t ha−1 biochar (ST), 7 t ha−1 straw + 5 t ha−1 biochar (SC1), 7 t ha−1 straw + 20 t ha−1 biochar (SC2), 7 t ha−1 straw + 40 t ha−1 biochar (SC3). The results indicated that the biochar had an encouraging effect on paddy fields with straw returning: (1) SC3 treatment significantly increased ammonium nitrogen (NH4+-N) and nitrate nitrogen (NO3−-N) content in soils compared to ST, increasing by 30.19% and 42.72%, while SC2 treatment increased by 25.84% and 30.40%, respectively; (2) Regarding soil phosphorus availability, ST treatment showed a negative effect, while proper biochar application rate (20 t ha−1) effectively increased Olsen-P content (18.24%); (3) No significant difference among these treatments was observed in the photosynthetic characteristics. Notably, 20 t ha−1 biochar application (SC2) effectively enhanced rice components (stem, ear) dry biomass, improved rice yield (10.14%), and Harvest index (HI: 4.99%). Hence, the appropriate rate (20 t ha−1) of biochar combined with straw (7 t ha−1) returning is a promising strategy for increasing nitrogen retention and phosphorous availability, alleviating N and P losses and promoting rice growth and yield. These findings are expected to provide a new perspective in that straw-returning with biochar achieves high efficiency, ecological, and sustainable development of agriculture.

Integrated Metabolomic and Network Analysis to Explore the Potential Mechanism of Three Chemical Elicitors in Rapamycin Overproduction.

Rapamycin is a polyketide macrocyclic antibiotic with exceptional pharmacological potential. To explore the potential mechanism of rapamycin overproduction, the intracellular metabolic differences of three chemical elicitor treatments were first investigated by combining them with dynamic metabolomics and network analysis. The metabolic response characteristics of each chemical elicitor treatment were identified by a weighted gene co-expression network analysis (WGCNA) model. According to the analysis of the identified metabolic modules, the changes in the cell membrane permeability might play a key role in rapamycin overproduction for dimethyl sulfoxide (DMSO) treatment. The enhancement of the starter unit of 4,5-dihydroxycyclohex-1-ene carboxylic acid (DHCHC) and the nicotinamide adenine dinucleotide phosphate (NADPH) availability were the main functions in the LaCl3 treatment. However, for sodium butyrate (SB), the improvement of the methylmalonyl-CoA and NADPH availability was a potential reason for the rapamycin overproduction. Further, the responsive metabolic pathways after chemical elicitor treatments were selected to predict the potential key limiting steps in rapamycin accumulation using a genome-scale metabolic network model (GSMM). Based on the prediction results, the targets within the reinforcement of the DHCHC and NADPH supply were selected to verify their effects on rapamycin production. The highest rapamycin yield improved 1.62 fold in the HT-aroA/zwf2 strain compared to the control.

Exploring the Impacts of Full-Scale Distribution System Orthophosphate Corrosion Control Implementation on the Microbial Ecology of Hydrologically Connected Urban Streams.

Many cities across the nation are plagued by lead contamination in drinking water. As such, many drinking water utilities have undertaken lead service line (LSL) replacement to prevent further lead contamination. However, given the urgency of lead mitigation, and the socioeconomic challenges associated with LSL replacement, cities have used phosphate-based corrosion inhibitors (i.e., orthophosphate) alongside LSL replacement. While necessary to ensure public health protection from lead contamination, the addition of orthophosphate into an aging and leaking drinking water system may increase the concentration of phosphate leaching into urban streams characterized by century-old failing water infrastructure. Such increases in phosphate availability may cascade into nutrient and microbial community composition shifts. The purpose of this study was to determine how this occurs and to understand whether full-scale distribution system orthophosphate addition impacts the microbial ecology of urban streams. Through monthly collection of water samples from five urban streams before and after orthophosphate addition, significant changes in microbial community composition (16S rRNA amplicon sequencing) and in the relative abundance of typical freshwater taxa were observed. In addition, key microbial phosphorus and nitrogen metabolism genes (e.g., two component regulatory systems) were predicted to change via BugBase. No significant differences in the absolute abundances of total bacteria, Cyanobacteria, and "Candidatus Accumulibacter" were observed. Overall, the findings from this study provide further evidence that urban streams are compromised by unintentional hydrologic connections with drinking water infrastructure. Moreover, our results suggest that infiltration of phosphate-based corrosion inhibitors can impact urban streams and have important, as-yet-overlooked impacts on urban stream microbial communities. IMPORTANCE Elevated lead levels in drinking water supplies are a public health risk. As such, it is imperative for cities to urgently address lead contamination from aging drinking water supplies by way of lead service line replacements and corrosion control methods. However, when applying corrosion control methods, it is also important to consider the chemical and microbiological effects that can occur in natural settings, given that our water infrastructure is aging and more prone to leaks and breaks. Here, we examine the impacts on the microbial ecology of five urban stream systems before and after full-scale distribution system orthophosphate addition. Overall, the results suggest that infiltration of corrosion inhibitors may impact microbial communities; however, future work should be done to ascertain the true impact to protect both public and environmental health.

Two-stage algal cultivation for the biotransformation of urban wastewater’s pollutants into multiple bioproducts in a circular bioeconomy paradigm

Resource recovery and recycling of urban wastewater have become essential due to rapidly depleting water resources. Here, a newly isolated cyanobacterium Pseudoscillatoria coralii BERC01 was employed for the biotreatment of urban wastewater (UWW) via a two-stage cultivation system followed by biotransformation of the biomass into multiple bioproducts. During the stage-I, the cyanobacterial strain BERC01 removed 100 % suspended solids (9–27 g/L) from the UWW within 3–7 days via biosorption, and the resultant biomass was used as a soil amender which improved the phosphate availability, microbial carbon biomass, and nitrate-nitrogen of the soil by 2.65–5.86-fold, 2.27–3.65-fold, and 3.20–6.57-fold, respectively. During stage-II, re-culturing the BERC01 in the recycled water improved the productivities of carbohydrates and proteins by 10-fold and 3-fold, respectively, when compared to the control. Cultivation of BERC01 also improved the pH of UWW (9.47 ± 0.2 – 10.93 ± 0.16) to reduce the bacterial and/or fungal contamination. The two-stage cultivation of BERC01 in the UWW lowered the total nitrogen, total phosphorous, chemical oxygen demand, and biological oxygen demand of the UWW by 41.94 %, 95 %, 79 %, and 89.64 %, respectively, bringing the quality of treated water within the WHO’s safety limits of agricultural purposes. Cascading processing of the stage-II biomass yielded food-grade pigments (phycocyanin = 148.95 ± 1.81 mg/g, allophycocyanin = 51.92 ± 0.51 mg/g), and 470–490 mg/g of lipids which contained compounds of pharmaceutical interest such as undecanoic acid, pentadecanoic acid, and eicosanoic acid. Finally, the pigment-free and de-oiled residual biomass (PDRB) was completely valorized to mycoprotein and α-amylase through fungal fermentation using 10–50 g/L PDRB as a sole source of nutrition. Resultantly, Aspergillus niger and Aspergillus oryzae produced 98.44 U/mL and 118.56 U/mL of α-amylase in 96 h of incubation, respectively, whereas the protein content of the fermented biomass was improved by 10.42-fold and 7.34-fold, respectively. This novel approach could help in achieving the economic and environmental sustainability of the algal biorefineries.