Efficient phosphate accumulation in the newly isolated Acinetobacter junii strain LH4

Monitoring Ammonium Polyphosphate (APP) Biodegradation by Acinetobacter nosocomialis D-3 Using DAPI

Ammonium polyphosphate (APP), a pivotal constituent within environmentally friendly flame retardants, exhibits notable decomposition susceptibility and potentially engenders ecological peril. Consequently, monitoring the APP concentration to ensure product integrity and facilitate the efficacious management of wastewater from production processes is of great significance. A fluorescent assay was devised to swiftly discern APP utilizing 4',6'-diamino-2-phenylindole (DAPI). With increasing APP concentrations, DAPI undergoes intercalation within its structure, emitting pronounced fluorescence. Notably, the flame retardant JLS-PNA220-A, predominantly comprising APP, was employed as the test substrate. Establishing a linear relationship between fluorescence intensity (F-F0) and JLS-PNA220-A concentration yielded the equation y = 76.08x + 463.2 (R2 = 0.9992), with a LOD determined to be 0.853 mg/L. The method was used to assess the degradation capacity of APP-degrading bacteria. Strain D-3 was isolated, and subsequent analysis of its 16S DNA sequence classified it as belonging to the Acinetobacter genus. Acinetobacter nosocomialis D-3 demonstrated superior APP degradation capabilities under pH 7 at 37 °C, with degradation rates exceeding 85% over a four-day cultivation period. It underscores the sensitivity and efficacy of the proposed method for APP detection. Furthermore, Acinetobacter nosocomialis D-3 exhibits promising potential for remediation of residual APP through environmental biodegradation processes.

Bacterial hosts of clinically significant beta-lactamase genes in Croatian wastewaters

Wastewater treatment plants (WWTPs) provide a suitable environment for the interaction of antibiotic resistant bacteria and antibiotic-resistance genes (ARGs) from human, animal, and environmental sources. The aim was to study the influent and effluent of two WWTPs in Croatia to identify bacterial hosts of clinically important beta-lactamase genes (blaTEM, blaVIM, blaOXA-48-like) and observe how their composition changes during the treatment process. A culture-independent epicPCR (Emulsion, Paired isolation and Concatenation Polymerase Chain Reaction) was used to identify the ARG hosts, and 16S rRNA amplicon sequencing to study the entire bacterial community. Different wastewater sources contributed to the significant differences in bacterial composition of the wastewater between the two WWTPs studied. A total of 167 genera were detected by epicPCR, with the Arcobacter genus, in which all ARGs studied were present, dominating in both WWTPs. In addition, the clinically important genera Acinetobacter and Aeromonas contained all ARGs examined. The blaOXA-48-like gene had the highest number of hosts, followed by blaVIM, while blaTEM had the narrowest host range. Based on 16S rRNA gene sequencing, ARG hosts were detected in both abundant and rare taxa. The number of hosts carrying investigated ARGs was reduced by wastewater treatment. EpicPCR provided valuable insights into the bacterial hosts of horizontally transmissible beta-lactamase genes in Croatian wastewater.

Spartina alterniflora invasion altered phosphorus retention and microbial phosphate solubilization of the Minjiang estuary wetland in southeastern China

Spartina alterniflora invasion is considered a critical event affecting sediment phosphorus (P) availability and stock. However, P retention and microbial phosphate solubilization in the sediments invaded with or without S. alterniflora have not been fully investigated. In this study, a sequential fractionation method and high-throughput sequencing were used to analyze P transformation and the underlying microbial mechanisms in the sediments of no plant (NP) zone, transition (T) zone, and plant (P) zone. Results showed that except for organic phosphate (OP), total phosphate (TP), inorganic phosphate (IP), and available phosphate (AP) all followed a significant decrease trend from the NP site to the T site, and to the P site. The vertical decrease of TP, IP, and AP was also observed with an increase in soil depth. Among the six IP fractions, Fe-P, Oc-P, and Ca10-P were the predominant forms, while the presence of S. alterniflora resulted in an obvious P depletion except for Ca8-P and Al-P. Although S. alterniflora invasion did not significantly alter the alpha diversity of phosphate-solubilizing bacteria (PSB) harboring phoD gene, several PSB belonging to p_Proteobacteria, p_Planctomycetes, and p_Cyanobacteriota showed close correlations with P speciation and IP fractions. Further correlation analysis revealed that the reduced soil pH, soil TN and soil EC, and the increased soil TOC mediated by the invasion of S. alterniflora also significantly correlated to these PSB. Overall, this study elucidates the linkage between PSB and P speciation and provides new insights into understanding P retention and microbial P transformation in the coastal sediment invaded by S. alterniflora.

Fixed-bed biofilter for polluted surface water treatment using chitosan impregnated-coconut husk biochar

Pelletizing biochar enables its use as a biofilter medium for polluted canal water treatment. Coconut husk biochar pellets and their modification with chitosan (CHC) were compared with conventional activated carbon pellets and gravel. The biofilter columns with these media were operated with a hydraulic loading rate of 0.1 m3/m2∙h. CHC showed the highest potential to reduce phosphate and nitrogen, via the adsorption process in the first week of filtration and later enhanced by biodegradation, to achieve removal efficiencies of 61.70 and 54.37% for these two key nutrients, respectively, over five weeks of biofilter operation. The predominant bacteria in the biofilter communities were characterized at the end of the experiments by next generation sequencing and quantitative polymerase chain reaction analysis. The biofilter communities included ammonium oxidizing, nitrite oxidizing, denitrifying, polyphosphate accumulating and denitrifying phosphate-accumulating bacteria that benefit nutrient removal. The CHC biofilter also effectively removed micropollutants, including pharmaceuticals.

Isolation and optimisation of polyphosphate accumulating bacteria for bio-treatment of phosphate from industrial wastewater

Phosphorus in wastewater influents is a global issue. Controlling eutrophic water is crucial. Biological phosphorus removal is an economically and environmentally sustainable method for removing phosphorus from wastewater. This study aims to isolate and improve the capacity of aerobic phosphorus-removing bacteria to reduce excessive phosphate concentrations in the environment. Only three out of fourteen bacterial isolates demonstrated the highest phosphate removal efficiency using Toluidine blue-O. Klebsiella pneumoniae 6A, Klebsiella quasipneumoniae 6R, and Enterobacter mori 8R were isolated from activated sludge and identified by 16srRNA. In a single-factor experiment, the effect of incubation periods, phosphate concentrations, carbon sources, sodium acetate concentrations, temperature, pH, and irradiation dosages were studied. Seventy-two hours of incubation, 55 mg/L PO4, sodium acetate as the carbon source, 30°C and pH 7 resulted in maximum phosphorus removal. After optimising the parameters, the removal efficiency of Klebsiella pneumoniae 6A, Klebsiella quasipneumoniae 6R, and Enterobacter mori 8R increased from 73.5% to 85.1%, 79.1% to 98.1%, and 80.6% to 91.9%, respectively. Gamma irradiation showed significant results only in Klebsiella pneumoniae 6A where 100 Gy increased the phosphorous removal efficiency from 85.1% to 100%. Immobilised mixed culture of the three strains adapted better to 100 mg/L Phosphorus than pure cells. Therefore, this technique holds great new promise for phosphorus-contaminated sites bioremediation.

Changes in BNR Microbial Community in Response to Different Selection Pressure

This study investigated structural changes in microbial community of biological nutrient removal (BNR) in response to changes in substrate composition (ammonium and phosphate), redox condition, and morphological characteristics (flocs to granules), with a focus on nitrification and phosphate removal. Analyzing treatment performance and 16S rRNA phylogenetic gene sequencing data suggested that heterotrophic nitrification (HN) and autotrophic nitrification (AN) potentially happened in aerobic organic-rich (HN_AS) and aerobic organic-deficient (AN_AS) activated sludge batch reactors, respectively. However, phosphate release and uptake were not observed under alternating anaerobic/aerobic regime. Phosphate release could not be induced even when anaerobic phase was extended, although Accumulibacter existed in the inoculum (5.1% of total bacteria). Some potential HN (e.g., Thauera, Acinetobacter, Flavobacterium), AN (e.g., Nitrosomonas (3.2%) and Nitrospira), and unconventional phosphate-accumulating organisms (PAOs) were identified. Putative HN bacteria (i.e., Thauera (29–36%) and Flavobacterium (18–25%)) were enriched in aerobic granular sludge (AGS) regardless of the granular reactor operation mode. Enrichment of HN organisms in the AGS was suspected to be mainly due to granulation, possibly due to the floc-forming ability of HN species. Thus, HN is likely to play a role in nitrogen removal in AGS reactors. This study is supposed to serve as a starting point for the investigation of the microbial communities of AS- and AGS-based BNR processes. It is recommended that the identified roles for the isolated bacteria are further investigated in future works.

Phosphorus and nitrogen removal by a novel phosphate-accumulating organism, Arthrobacter sp. HHEP5 capable of heterotrophic nitrification-aerobic denitrification: Safety assessment, removal characterization, mechanism exploration and wastewater treatment

A novel phosphate-accumulating organism (PAO), Arthrobacter sp. HHEP5 was isolated from mariculture effluents. It produced no hemolysin and was susceptible to most antibiotics. It had removal efficiencies of above 99% for 1-10 mg/L phosphorus at 18-28 °C, pH 5.5-8.5, salinities 0-3%, C/N ratios 5-20, P/N ratios 0.1-0.2 and 20-260 rpm. It exhibited simultaneous aerobic phosphorus removal, nitrification and denitrification with the highest ammonium, nitrite, nitrate removal efficiencies of 99.87%, 100%, 99.37%. Phosphorus removal was accomplished by assimilating phosphate with the existence of polyphosphate kinase completely under aerobic condition. Genes involved in nitrogen removal were amplified. 99% of phosphorus and 95% of nitrogen in both mariculture and domestic wastewater were removed by HHEP5. This study provided sound methods for future screening of PAOs and new perspectives for renewed cognition of phosphorus removal process. Wide adaptation and remarkably aerobic phosphorus, nitrogen removal performances would make HHEP5 a promising candidate in wastewater treatment.

Isolation of two iron-reducing facultative anaerobic electricigens and probing the application performance in eutrophication water

Purpose

Sediment microbial fuel cell (SMFC) is a promising bioremediation technology in which microbes play an important role. Electricigens as the bio-catalysts have effect on pollution control and electricity generation. It is of great significance to screen the microorganisms with the ability of generating electricity.

Methods

The SMFC anode biofilm was used as microbiological source to study the feasibility of electricigens with iron-reducing property for eutrophication water treatment. Preliminarily, we isolated 20 facultative anaerobic pure bacteria and evaluated their cyclic voltammogram (CV) through the three-electrode system and electrochemical workstation. The power generation performance of strains was verified by air-cathode microbial fuel cells (AC-MFCs) under different single carbon sources.

Result

According to its morphological, physiological, and biochemical characteristics, along with phylogenetic analysis, the two strains (SMFC-7 and SMFC-17) with electrical characteristics were identified as Bacillus cereus. Compared with SMFC-7, SMFC-17 exhibited efficient NH4+-N and NO3−-N removal and PO43−-P accumulation from eutrophic solution with a removal rate of 79.91 ± 6.34% and 81.26 ± 1.11% and accumulation rate of 57.68 ± 4.36%, respectively.

Conclusion

The isolated bacteria SMFC-17 showed a good performance in eutrophic solution, and it might be a useful biocatalyst to enable the industrialized application of SMFC in eutrophic water treatment.

Isolation and Characterization of Phosphorus Solubilizing Bacteria With Multiple Phosphorus Sources Utilizing Capability and Their Potential for Lead Immobilization in Soil

Phosphorus solubilizing bacteria (PSB) can promote the level of plant-absorbable phosphorus (P) in agro-ecosystems. However, little attention has been paid to PSB harboring abilities in utilizing multiple phosphorus sources and their potentials for heavy metal immobilization. In this study, we applied the strategy of stepwise acclimation by using Ca₃(PO₄)₂, phytate, FePO₄, and AlPO₄ as sole P source. We gained 18 PSB possessing abilities of multiple P sources utilization, and these bacteria belonged to eight genera (Acinetobacter, Pseudomonas, Massilia, Bacillus, Arthrobacter, Stenotrophomonas, Ochrobactrum, and Cupriavidus), and clustered to two apparent parts: Gram-positive bacteria and Gram-negative bacteria. The isolate of Acinetobacter pittii gp-1 presented good performance for utilizing Ca₃(PO₄)₂, FePO₄, AlPO₄, and phytate, with corresponding P solubilizing levels were 250.77, 46.10, 81.99, and 7.91 mg/L PO₄^3–-P, respectively. The PSB A. pittii gp-1 exhibited good performance for solubilizing tricalcium phosphate in soil incubation experiments, with the highest values of water soluble P and available P were 0.80 and 1.64 mg/L, respectively. Additionally, the addition of A. pittii gp-1 could promote the immobilization of lead (Pb), and the highest Pb immobilization efficiency reached 23%. Simultaneously, we found the increases in abundances of both alkaline phosphatase gene (phoD) and β-propeller phytase gene (bpp) in strain gp-1 added soils. Besides, we observed the expression up-regulation of both pyrroloquinoline quinone gene (pqq) and polyphosphate kinases gene (ppk), with the highest relative expression levels of 18.18 and 5.23, respectively. We also found the polyphosphate particles using granule staining. To our knowledge, our findings first suggest that the solubilizing of tricalcium phosphate by phosphorus solubilizing bacterium belonging to Acinetobacter is coupled with the synthesis of polyphosphate. Taken together, A. pittii gp-1 could be a good candidate in improving soil fertility and quality.