Ecological Insights Into Community Interactions, Assembly Processes and Function in the Denitrifying Phosphorus Removal Activated Sludge Driven by Phosphorus Sources

The microbial characteristics in the wastewater treatment plants (WWTPs) strongly affect their optimal performance and functional stability. However, a cognitive gap remains regarding the characteristics of the microbial community driven by phosphorus sources, especially co-occurrence patterns and community assembly based on phylogenetic group. In this study, 59 denitrifying phosphorus removal (DPR) activated sludge samples were cultivated with phosphorus sources. The results suggested that homogeneous selection accounted for the largest proportion that ranged from 35.82 to 64.48%. Deterministic processes dominated in 12 microbial groups (bins): Candidatus_Accumulibacter and Pseudomonas in these bins belonged to phosphate-accumulating organisms (PAOs). Network analysis revealed that species interactions were intensive in cyclic nucleoside phosphate-influenced microbiota. Function prediction indicated that cyclic nucleoside phosphates increased the activity of enzymes related to denitrification and phosphorus metabolism and increased the α-diversity of microorganism but decreased the diversity of metabolic function. Based on these results, it was assumed that cyclic nucleoside phosphates, rather than inorganic phosphates, are the most available phosphorus source for majority microorganisms in DPR activated sludge. The study revealed the important role of phosphorus source in the construction and assembly of microbial communities and provided new insights about pollutant removal from WWTPs.

Growth and Productivity Augmentation of Greengram (Vigna radiata) through Phosphorus Sources and Sulphur Levels

Background: Being an efficient N- fixer, mungbean improve the soil fertility status and can thereby serve as a useful component in any viable cropping system in the country. PROM has to be a better source of phosphate application. Indian soils are deficient in organic carbon. Sulphur is mostly applied to oilseed and pulse crops found to benefit more than one crop in a sequence due to its significant residual response. Methods: The investigation was conducted during kharif season of 2019 comprising five levels of phosphorus sources (Control, 16 kg P2O5/ha through DAP, 16 kg P2O5/ha through PROM, 32 kg P2O5/ha through DAP and 32 kg P2O5/ha through PROM) and three levels of sulphur (Control, 15 and 30 kg/ha) making 15 treatment combinations replicated three times in factorial randomized block design. Result: Application of 32 kg P2O5/ha through PROM recorded significantly higher growth, yield attributes, yields as well as net returns ( 50440) with B:C ratio 2.93 as compared to 16 kg P2O5/ha through DAP, 16 kg P2O5/ha through PROM and 32 kg P2O5/ha through DAP. With regard to sulphur levels application of sulphur up to 30 kg/ha recorded significantly higher growth, yield attributes, yields as well net returns ( 46723) with B:C ratio 2.96 over control and 15 kg S/ha.

Yield and Nutrient Uptake of Rapeseed (Brassica campestris var. toria) as Influenced by Phosphorus Sources and Levels in Acidic Soils of Meghalaya

Background: Acidic soils limit the soil phosphorus availability to the crop plants because these soils have tendency to fix P as iron and aluminium phosphate. The present study aims to investigate the influence of phosphorus sources and levels on yield and nutrient uptake of rapeseed (Brassica campestris var. toria) in acidic soils of Meghalaya. Methods: A pot culture experiment was conducted during rabi season of 2016-17 wherein two sources of P (single super phosphate and Mussoorie rock phosphate) and six levels of P (0, 30, 60, 90, 120 and 150 mg P kg-1 of soil) were tested in two types of acidic soils (Alfisols, Inceptisols) in completely randomized design with three replication and rapeseed (cv. M-27) as test crop. Result: The highest mean dry matter yield of rapeseed (16.1 g pot-1) was recorded with 120 mg P kg-1 of soil. Subsequent increase in the level of P significantly decreased the dry matter yield by 4.6% over 120 mg P kg-1. The dry matter yield with Mussorie rock phosphate was lower as compared to single sulphur phosphate (SSP) at each levels of P irrespective of soil type. The concentration of P in plant dry matter of rapeseed increased with each successive levels of P in acidic soils with both P sources; however P uptake increased up to 120 mg P kg-1 soil.

Immobilization of Pb by organic and inorganic phosphate and calcium sources in an acidic Pb-polluted soil amended with cow manure

Background: Chemical stabilization of heavy metals in acidic soil is one of the important points in environmental pollution. Thus, this research was conducted to investigate the effect of organic and inorganic amendments on lead (Pb) immobilization in the Pb-polluted soil. Methods: Treatments were consisted of applying cow manure (0, 15, and 30 t/ha), and applying cow bone and phosphate rock (5% (W/W)) in the Pb (0, 800, and 1600 mg Pb/kg soil)-polluted soil. The plant used in this experiment was canola. After 70 days, the plants were harvested and soil and plant Pb concentration was measured using atomic absorption spectroscopy (AAS). Results: Applying 15 and 30 t/ha of cow manure in the Pb (1600 mg Pb/kg soil)-polluted soil significantly decreased the soil Pb concentration by 14.3 and 17.2%, respectively. For plant Pb concentration, it was increased by 11.8 and 15.1%, respectively. A significant decrease in plant Pb concentration was measured, when the soil under cultivation of the plant was amended with 5% (W/W) phosphate rock powder. For the plants grown on the soil, which was amended with 5% (W/W), the plant Pb concentration decreased by 17.6%. In addition, applying organic and inorganic amendment significantly decreased the bio-concentration factor (BCF), while the soil microbial respiration increased. Conclusion: The results of this study showed that applying 15 and 30 t/ha cow manure or calcium and phosphorus sources such as cow bone and phosphate rock powder (5% (W/W) can decrease the soil Pb availability and prevent the Pb translocation from soil to plants.

Characterization and engineering of Streptomyces griseofuscus DSM 40191 as a potential host for heterologous expression of biosynthetic gene clusters

Streptomyces griseofuscus DSM 40191 is a fast growing Streptomyces strain that remains largely underexplored as a heterologous host. Here, we report the genome mining of S. griseofuscus, followed by the detailed exploration of its phenotype, including the production of native secondary metabolites and ability to utilise carbon, nitrogen, sulphur and phosphorus sources. Furthermore, several routes for genetic engineering of S. griseofuscus were explored, including use of GusA-based vectors, CRISPR-Cas9 and CRISPR-cBEST-mediated knockouts. Two out of the three native plasmids were cured using CRISPR-Cas9 technology, leading to the generation of strain S. griseofuscus DEL1. DEL1 was further modified by the full deletion of a pentamycin BGC and an unknown NRPS BGC, leading to the generation of strain DEL2, lacking approx. 500 kbp of the genome, which corresponds to a 5.19% genome reduction. DEL2 can be characterized by faster growth and inability to produce three main native metabolites: lankacidin, lankamycin, pentamycin and their derivatives. To test the ability of DEL2 to heterologously produce secondary metabolites, the actinorhodin BGC was used. We were able to observe a formation of a blue halo, indicating a potential production of actinorhodin by both DEL2 and a wild type.