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Mondal S, Biswas B, Chowdhury R, Sengupta R, Mandal A, Kotal HN, Giri CK, Ghosh A, Saha S, Begam MM, Mukherjee C, Das I, Basak SK, Mitra Ghosh M, Ray K. Estuarine mangrove niches select cultivable heterotrophic diazotrophs with diverse metabolic potentials-a prospective cross-dialog for functional diazotrophy. Front Microbiol 2024; 15:1324188. [PMID: 38873137 PMCID: PMC11174608 DOI: 10.3389/fmicb.2024.1324188] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2023] [Accepted: 05/10/2024] [Indexed: 06/15/2024] Open
Abstract
Introduction Biological nitrogen fixation (BNF), an unparalleled metabolic novelty among living microorganisms on earth, globally contributes ~88-101 Tg N year-1 to natural ecosystems, ~56% sourced from symbiotic BNF while ~22-45% derived from free-living nitrogen fixers (FLNF). The success of symbiotic BNF is largely dependent on its interaction with host-plant, however ubiquitous environmental heterotrophic FLNFs face many limitations in their immediate ecological niches to sustain unhindered BNF. The autotrophic FLNFs like cyanobacteria and oceanic heterotrophic diazotrophs have been well studied about their contrivances acclimated/adapted by these organisms to outwit the environmental constraints for functional diazotrophy. However, FLNF heterotrophs face more adversity in executing BNF under stressful estuarine/marine/aquatic habitats. Methods In this study a large-scale cultivation-dependent investigation was accomplished with 190 NCBI accessioned and 45 non-accessioned heterotrophic FLNF cultivable bacterial isolates (total 235) from halophilic estuarine intertidal mangrove niches of Indian Sundarbans, a Ramsar site and UNESCO proclaimed World Heritage Site. Assuming ~1% culturability of the microbial community, the respective niches were also studied for representing actual bacterial diversity via cultivation-independent next-generation sequencing of V3-V4 rRNA regions. Results Both the studies revealed a higher abundance of culturable Gammaproteobacteria followed by Firmicutes, the majority of 235 FLNFs studied belonging to these two classes. The FLNFs displayed comparable selection potential in media for free nitrogen fixers and iron-oxidizing bacteria, linking diazotrophy with iron oxidation, siderophore production, phosphorus solubilization, phosphorus uptake and accumulation as well as denitrification. Discussion This observation validated the hypothesis that under extreme estuarine mangrove niches, diazotrophs are naturally selected as a specialized multidimensional entity, to expedite BNF and survive. Earlier metagenome data from mangrove niches demonstrated a microbial metabolic coupling among C, N, P, S, and Fe cycling in mangrove sediments, as an adaptive trait, evident with the co-abundant respective functional genes, which corroborates our findings in cultivation mode for multiple interrelated metabolic potential facilitating BNF in a challenging intertidal mangrove environment.
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Affiliation(s)
- Sumana Mondal
- Environmental Biotechnology Group, Department of Botany, West Bengal State University, Kolkata, India
| | - Biswajit Biswas
- Environmental Biotechnology Group, Department of Botany, West Bengal State University, Kolkata, India
- Department of Microbiology, St. Xavier’s College (Autonomous), Kolkata, India
| | - Rajojit Chowdhury
- Environmental Biotechnology Group, Department of Botany, West Bengal State University, Kolkata, India
- Department of Botany, Sree Chaitanya College, Habra, India
| | - Rudranil Sengupta
- Environmental Biotechnology Group, Department of Botany, West Bengal State University, Kolkata, India
| | - Anup Mandal
- Environmental Biotechnology Group, Department of Botany, West Bengal State University, Kolkata, India
| | - Hemendra Nath Kotal
- Environmental Biotechnology Group, Department of Botany, West Bengal State University, Kolkata, India
| | - Chayan Kumar Giri
- Environmental Biotechnology Group, Department of Botany, West Bengal State University, Kolkata, India
| | - Anjali Ghosh
- Environmental Biotechnology Group, Department of Botany, West Bengal State University, Kolkata, India
| | - Subhajit Saha
- Environmental Biotechnology Group, Department of Botany, West Bengal State University, Kolkata, India
| | - Mst Momtaj Begam
- Environmental Biotechnology Group, Department of Botany, West Bengal State University, Kolkata, India
- Department of Botany, Kalimpong College, Darjeeling, India
| | - Chandan Mukherjee
- Environmental Biotechnology Group, Department of Botany, West Bengal State University, Kolkata, India
- School of Biological and Life Sciences, Galgotias University, Greater Noida, India
| | - Ipsita Das
- Environmental Biotechnology Group, Department of Botany, West Bengal State University, Kolkata, India
| | | | | | - Krishna Ray
- Environmental Biotechnology Group, Department of Botany, West Bengal State University, Kolkata, India
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Ameliorating effect of nitrate on nitrite inhibition for denitrifying P-accumulating organisms. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 797:149133. [PMID: 34311377 DOI: 10.1016/j.scitotenv.2021.149133] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Revised: 06/17/2021] [Accepted: 07/14/2021] [Indexed: 02/08/2023]
Abstract
Lowered air supply and organic carbon need are the key factors to reduce wastewater treatment costs and thereby, avoid eutrophication. Denitrifying PO43-- removal (DPR) process using nitrate instead of oxygen for PO43- uptake was started up in the sequencing batch reactor (SBR) at a nitrate dosing rate of 20-25 mg N L-1 d-1. Operation with a real municipal wastewater supplied with CH3COONa, K2HPO4 and KNO3 succeeded in the cultivation of biomass containing denitrifying polyphosphate accumulating organisms (DPAOs). The durations of SBR process anaerobic/anoxic/oxic cycles were 1.5 h, 3.5 h and 1 h, respectively. SBR operation resulted in a maximum PO43--P uptake of 17 mg PO43--P g-1 MLSS. The highest TN and PO43- removal efficiencies were observed during the first half of reactor operation at 77 (±10) % and 71 (±5) %, respectively. An average COD removal rate of 172 (±98) mg g-1 MLSS and a high average removal efficiency of 89 (±4) % were achieved. Nitrite effect with/without nitrate as DPR electron acceptor was investigated in batch-scale to show possibilities to use high nitrite and nitrate contents simultaneously as electron acceptors for the anoxic phosphate uptake. Nitrate attenuation against nitrite toxicity can be economically justified in full-scale treatment applications in which wastewater has a high nitrogen content. Nitrate attenuated nitrite toxicity (caused by nitrite content at 5-100 mg NO2--N L-1) when using supplemental additions of nitrate (at concentrations of 45-200 mg NO3--N L-1) in batch tests. Illumina sequencing emphasized that during biomass adaption microbial community changed by lowered aerobic cycle length and by lowered nitrate dosing towards representation of key DPAO/PAO- organisms, such as Candidatus Accumulibacter, Xanthomonadaceae, Comomonadaceae, Saprospiraceae and Rhodocyclaceae. This study showed that DPAO biomass adaption to nitrate maintained an efficient COD, nitrogen and phosphorus removal and the biomass can be applied for treatment of wastewater containing high nitrite and nitrate content.
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Vučić V, Süring C, Harms H, Müller S, Günther S. A framework for P-cycle assessment in wastewater treatment plants. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 760:143392. [PMID: 33223155 DOI: 10.1016/j.scitotenv.2020.143392] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Revised: 10/15/2020] [Accepted: 10/16/2020] [Indexed: 06/11/2023]
Abstract
Phosphorus (P) in wastewater has a variety of negative effects and is usually permanently lost as a non-renewable resource. To mitigate future P shortage, P must be recovered from wastewater, preferably by bio-based technologies to avoid toxic side streams. A standardized procedure for the determination of P types and P concentrations in all liquid and solid process stages was established, which is applicable to all full-scale wastewater treatment plants (WWTPs). Based on this, an equally universal calculation framework for P-cycle assessment based on volume flow and mass load rates was designed to identify the most promising process streams for biological P recovery. As an example, in 16 process streams of a typical WWTP, concentrations of free, bound and total P were calculated and microbial communities were analyzed by flow cytometry over 748 days. The most promising process streams for the recovery of free P were anaerobic digester sludge, centrate and the water-extracts of the biosolids with 0.510 kg P m-3, 0.075 kg P m-3 and 1.023 kg P m-3, while the best process streams for the recovery of bound P were return sludge, excess sludge, anaerobic digester sludge, and the solids of the biosolids with 0.300 kg P m-3, 0.268 kg P m-3, 0.213 kg P m-3 and 1.336 kg P m-3, respectively. Microorganisms capable of P accumulation were active in all process stages and it was observed that chemical P precipitation antagonizes biological P removal. The framework for P-cycle assessment was able to identify process streams that are economically viable to make future in-stream technologies for biological P removal feasible.
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Affiliation(s)
- Vedran Vučić
- Helmholtz Centre for Environmental Research - UFZ, Department Environmental Microbiology, Permoserstrasse 15, 04318 Leipzig, Germany
| | - Christine Süring
- Helmholtz Centre for Environmental Research - UFZ, Department Environmental Microbiology, Permoserstrasse 15, 04318 Leipzig, Germany
| | - Hauke Harms
- Helmholtz Centre for Environmental Research - UFZ, Department Environmental Microbiology, Permoserstrasse 15, 04318 Leipzig, Germany
| | - Susann Müller
- Helmholtz Centre for Environmental Research - UFZ, Department Environmental Microbiology, Permoserstrasse 15, 04318 Leipzig, Germany.
| | - Susanne Günther
- Helmholtz Centre for Environmental Research - UFZ, Department Environmental Microbiology, Permoserstrasse 15, 04318 Leipzig, Germany
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