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Ma W, Lian J, Rene ER, Zhang P, Liu X. Enhanced thyroxine removal from micro-polluted drinking water resources in a bio-electrochemical reactor amended with TiO 2@GAC particles: Efficiency, mechanism and energy consumption. ENVIRONMENTAL RESEARCH 2023; 237:116949. [PMID: 37625538 DOI: 10.1016/j.envres.2023.116949] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2023] [Revised: 08/17/2023] [Accepted: 08/20/2023] [Indexed: 08/27/2023]
Abstract
A three-dimensional bioelectrochemical system (3D-BES) with both electrocatalytic and biodegradation functions was designed and developed to enhance iodine-containing hormone removal from micro-polluted oligotrophic drinking water sources and to reduce energy consumption. Thyroxine (T4) removal efficiency was 99.0% in the 3D-BES amendment with TiO2@GAC as the particle electrodes, which was 20.5% higher than the total efficiency of single biodegradation (28.7%) plus electrochemical decomposition (49.8%). The high T4 removal efficiency was a result of biochemical synergistic degradation, enhancement of electron transfer and utilization, enrichment of functional microorganisms, and the expression of dehalogenation functional genes. The electron transfer was increased by 1.63 times in 3D-BES compared to the 2D-BES, which contributed to: (i) ∼17.8% enhancement of dehalogenation, (ii) 2.35 times enhancement of the attenuation rate, and (iii) 60% reduction in energy consumption. Moreover, the aggregation of microorganisms and the hydrophobic T4 onto TiO2@GAC shortened the transfer distance of matter and energy, which induced the degradation steps to be shortened and the toxic decay to be accelerated from T4 and its metabolites. These comprehensive functions also enhanced the 31.8% ATPase activity, 7.3% abundance of the functional reductive dehalogenation genera, and 52.3% dehalogenation genes expression for Pseudomonas, Ancylobacter, and Dehalogenimonas, which contributed to an increase in T4 removal. This work provides an environmental-friendly biochemical synergistic method for the detoxification of T4 polluted water.
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Affiliation(s)
- Weifang Ma
- College of Environmental Science and Engineering, Beijing Forestry University, Beijing, 100083, China.
| | - Jiangru Lian
- College of Environmental Science and Engineering, Beijing Forestry University, Beijing, 100083, China
| | - Eldon R Rene
- Department of Water Supply, Sanitation and Environmental Engineering, IHE Delft Institute for Water Education, Westvest 7, P.O. Box 3015, 2601DA, Delft, the Netherlands
| | - Panyue Zhang
- College of Environmental Science and Engineering, Beijing Forestry University, Beijing, 100083, China
| | - Xiang Liu
- School of Environment, Tsinghua University, Beijing, 100084, China
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2
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Ni QZ, Sierra BN, La Clair JJ, Burkart MD. Chemoenzymatic elaboration of the Raper-Mason pathway unravels the structural diversity within eumelanin pigments. Chem Sci 2020; 11:7836-7841. [PMID: 34123072 PMCID: PMC8163323 DOI: 10.1039/d0sc02262d] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Melanin is a central polymer in living organisms, yet our understanding of its molecular structure remains unresolved. Here, we apply a biosynthetic approach to explore the composite structures accessible in one type of melanin, eumelanin. Using a combination of solid-state NMR, dynamic nuclear polarization, and electron microscopy, we reveal how a variety of monomers are enzymatically polymerized into their corresponding eumelanin pigments. We demonstrate how this approach can be used to unite structure with an understanding of enzymatic activity, substrate scope, and the regulation of nanostructural features. Overall, this data reveals how intermediate metabolites of the Raper–Mason metabolic pathway contribute to polymerization, allowing us to revisit the original proposal of how eumelanin is biosynthesized. Melanin is a central polymer in living organisms, yet our understanding of its molecular structure remains unresolved.![]()
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Affiliation(s)
- Qing Zhe Ni
- Department of Chemistry and Biochemistry, University of California San Diego, 9500 Gilman Drive La Jolla CA 92093-0358 USA
| | - Brianna N Sierra
- Department of Chemistry and Biochemistry, University of California San Diego, 9500 Gilman Drive La Jolla CA 92093-0358 USA
| | - James J La Clair
- Department of Chemistry and Biochemistry, University of California San Diego, 9500 Gilman Drive La Jolla CA 92093-0358 USA
| | - Michael D Burkart
- Department of Chemistry and Biochemistry, University of California San Diego, 9500 Gilman Drive La Jolla CA 92093-0358 USA
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Ahmad S, Mohammed M, Mekala LP, Chintalapati S, Chintalapati VR. Tryptophan, a non-canonical melanin precursor: New L-tryptophan based melanin production by Rubrivivax benzoatilyticus JA2. Sci Rep 2020; 10:8925. [PMID: 32488041 PMCID: PMC7265499 DOI: 10.1038/s41598-020-65803-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2020] [Accepted: 05/08/2020] [Indexed: 11/20/2022] Open
Abstract
Melanins are chemically diverse ubiquitous pigments found across the life forms synthesized via different biochemical pathways mainly from L-tyrosine or acetyl CoA. Though few reports suggest the possibility of tryptophan-based melanin synthesis, however, such tryptophan-based melanin and its biosynthesis remained a biochemical riddle. Here we report tryptophan-based melanin production by bacterium, Rubrivivax benzoatilyticus JA2. Aerobic cultures of strain JA2 produced brown pigment when grown on L-tryptophan-containing media. Purified pigment showed typical physico-chemical properties of melanin. Further, extensive spectroscopic studies revealed that pigment is an amorphous, indole-type polymer with stable free radical centers. Further, hydrolysis of the brown pigment revealed the presence of indole moiety, confirming the indolic nature of the pigment. Demonstration of in vitro and in vivo pigment synthesis directly from L-tryptophan or hydroxytryptophan confirms tryptophan-based melanin synthesis in strain JA2. Interestingly, canonical melanin biosynthetic inhibitors did not affect the pigment synthesis indicating possible non-canonical tryptophan-based melanin biosynthesis in strain JA2. Further, the exometabolite profiling and precursor feeding studies suggests that L-tryptophan converted to hydroxytryptophan/hydroxyindoles and their subsequent polymerization lead to the formation of melanin. The current study sheds light on biosynthetic diversity of melanins and L-tryptophan can be a potential precursor for melanin synthesis in life forms.
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Affiliation(s)
- Shabbir Ahmad
- Department of Plant Sciences, School of Life Sciences, University of Hyderabad, Hyderabad, 500046, India
| | - Mujahid Mohammed
- Department of Plant Sciences, School of Life Sciences, University of Hyderabad, Hyderabad, 500046, India.,Department of Botany, Bharathidasan Government College for Women, Puducherry, U.T. - 605003, India
| | - Lakshmi Prasuna Mekala
- Department of Plant Sciences, School of Life Sciences, University of Hyderabad, Hyderabad, 500046, India.,Department of Plant Sciences, Avvaiyar Government College for Women, Karaikal, Puducherry, U.T 609602, India
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Mohammed M, Mekala LP, Chintalapati S, Chintalapati VR. New insights into aniline toxicity: Aniline exposure triggers envelope stress and extracellular polymeric substance formation in Rubrivivax benzoatilyticus JA2. JOURNAL OF HAZARDOUS MATERIALS 2020; 385:121571. [PMID: 31753663 DOI: 10.1016/j.jhazmat.2019.121571] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2019] [Revised: 09/12/2019] [Accepted: 10/29/2019] [Indexed: 05/16/2023]
Abstract
Aniline is a major environmental pollutant of serious concern due to its toxicity. Although microbial metabolism of aniline is well-studied, its toxic effects and physiological responses of microorganisms to aniline are largely unexplored. Rubrivivax benzoatilyticus JA2, an aniline non-degrading bacterium, tolerates high concentrations of aniline and produces extracellular polymeric substance(EPS). Surprisingly, strain JA2 forms EPS only when exposed to aniline and other toxic compounds like organic solvents and heavy metals indicating that EPS formation is coupled to cell toxicity. Further, extensive reanalysis of the previous proteomic data of aniline exposed cells revealed up-regulation of envelope stress response(ESR) proteins such as periplasmic protein folding, envelope integrity, transmembrane complex, and cell-wall remodelling proteins. In silico analysis and molecular modeling of three highly up-regulated proteins revealed that these proteins were homologous to CpxARP proteins of ESR signalling pathway. Furthermore, EPS formation to known ESR activators(Triton-X-100, EDTA) suggests that envelope stress possibly regulating the EPS production. The present study suggests that aniline triggers envelope stress; to counter this strain JA2 activates ESR pathway and EPS production. Our study revealed the hitherto unknown toxic effects of aniline as an acute envelope stressor thus toxicity of aniline may be more profound to life-forms than previously thought.
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Affiliation(s)
- Mujahid Mohammed
- Department of Plant Sciences, School of Life Sciences, University of Hyderabad, P.O. Central University, Hyderabad 500 046, India
| | - Lakshmi Prasuna Mekala
- Department of Plant Sciences, School of Life Sciences, University of Hyderabad, P.O. Central University, Hyderabad 500 046, India
| | - Sasikala Chintalapati
- Bacterial Discovery Laboratory, Center for Environment, IST, JNT University Hyderabad, Kukatpally, Hyderabad 500 085, India
| | - Venkata Ramana Chintalapati
- Department of Plant Sciences, School of Life Sciences, University of Hyderabad, P.O. Central University, Hyderabad 500 046, India.
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Shu Z, Miao X, Tang T, Zhan P, Zeng L, Jiang Y. The GSK‑3β/β‑catenin signaling pathway is involved in HMGB1‑induced chondrocyte apoptosis and cartilage matrix degradation. Int J Mol Med 2020; 45:769-778. [PMID: 31922219 PMCID: PMC7015138 DOI: 10.3892/ijmm.2020.4460] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2019] [Accepted: 12/10/2019] [Indexed: 01/06/2023] Open
Abstract
Knee osteoarthritis (KOA) is a common joint disease with a high incidence rate among middle‑aged and elderly individuals. However, the precise underlying pathological mechanisms and effective treatment of this disease remain to be determined. To explore the effect of high mobility group box 1 (HMGB1) on chondrocyte apoptosis and catabolism, the ATDC5 cell line was cultured as an in vitro model for cartilage research. Cultured cells were treated with recombinant HMGB1 at different concentrations. Hoechst staining and flow cytometry demonstrated that HMGB1 administration significantly induced apoptosis of ATDC5 cells, which was the same as the effect of interleukin‑1β treatment. HMGB1 also induced cartilage matrix degradation, as shown by Alcian blue staining. Moreover, HMGB1 markedly upregulated the expression levels of matrix metallopeptidases (MMPs) and a disintegrin and metalloproteinase with thrombospondin motifs (ADAMTS), while genetic silencing of HMGB1 significantly suppressed their expressions. The glycogen synthase kinase (GSK)‑3β/β‑catenin pathway was activated upon HMGB1 treatment. Pharmacological inhibitors or HMGB1 knockdown inactivated the GSK‑3β/β‑catenin pathway, inhibited the expression levels of downstream genes, including MMPs and ADAMTS, and attenuated the apoptosis of ATDC5 cells. Furthermore, the data demonstrated that HMGB1 promoted chondrocyte dysfunction via the regulation of estrogen sulfotransferase and Runt‑related transcription factor 2. Thus, the findings of the present study demonstrated that HMGB1 induces chondrocyte cell apoptosis via activation of GSK‑3β/β‑catenin and the subsequent expression of multiple targeted genes.
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Affiliation(s)
- Zhiyong Shu
- Department of Orthopedics, Zhuhai People's Hospital, Zhuhai, Guangdong 519000, P.R. China
| | - Xiaogang Miao
- Department of Orthopedics, Zhuhai People's Hospital, Zhuhai, Guangdong 519000, P.R. China
| | - Tainhua Tang
- Department of Orthopedics, Zhuhai People's Hospital, Zhuhai, Guangdong 519000, P.R. China
| | - Peng Zhan
- Department of Orthopedics, Zhuhai People's Hospital, Zhuhai, Guangdong 519000, P.R. China
| | - Langqing Zeng
- Department of Orthopedics, Zhuhai People's Hospital, Zhuhai, Guangdong 519000, P.R. China
| | - Yuwen Jiang
- Department of Orthopedics, Zhuhai People's Hospital, Zhuhai, Guangdong 519000, P.R. China
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Ranganath LR, Norman BP, Gallagher JA. Ochronotic pigmentation is caused by homogentisic acid and is the key event in alkaptonuria leading to the destructive consequences of the disease-A review. J Inherit Metab Dis 2019; 42:776-792. [PMID: 31282009 DOI: 10.1002/jimd.12152] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Revised: 07/04/2019] [Accepted: 07/05/2019] [Indexed: 02/06/2023]
Abstract
Ochronosis is the process in alkaptonuria (AKU) that causes all the debilitating morbidity. The process involves selective deposition of homogentisic acid (HGA)-derived pigment in tissues altering the properties of these tissues, leading to their failure. Some tissues like cartilage are more easily affected by ochronosis while others such as the liver and brain are unaffected for reasons that are still not understood. In vitro and mouse models of ochronosis have confirmed the dose relationships between HGA and ochronosis and also their modulation by p-hydroxyphenylpyruvate dioxygenase inhibition. Ochronosis cannot be fully reversed and is a key factor in influencing treatment decisions. Earlier detection of ochronosis preferably by noninvasive means is desirable. A cause-effect relationship between HGA and ochronosis is discussed. The similarity in AKU and familial hypercholesterolaemia is explored and lessons learnt. More research is needed to more fully understand the crucial nature of ochronosis.
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Affiliation(s)
- Lakshminarayan R Ranganath
- Royal Liverpool University Hospital, Liverpool, UK
- Musculoskeletal Biology I, Institute of Ageing & Chronic Disease, William Henry Duncan Building, University of Liverpool, Liverpool, UK
| | - Brendan P Norman
- Musculoskeletal Biology I, Institute of Ageing & Chronic Disease, William Henry Duncan Building, University of Liverpool, Liverpool, UK
| | - James A Gallagher
- Musculoskeletal Biology I, Institute of Ageing & Chronic Disease, William Henry Duncan Building, University of Liverpool, Liverpool, UK
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Precursor-feeding and altered-growth conditions reveal novel blue pigment production by Rubrivivax benzoatilyticus JA2. Biotechnol Lett 2019; 41:813-822. [PMID: 31069568 DOI: 10.1007/s10529-019-02682-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2018] [Accepted: 05/02/2019] [Indexed: 12/30/2022]
Abstract
OBJECTIVE To explore the secondary metabolite biosynthetic potential of Rubrivivax benzoatilyticus JA2 using a new metabolite mining strategy. RESULTS Combination of precursor-feeding and altered growth conditions were used to mine new biomolecules. Strain JA2 utilised L-phenylalanine as sole source of nitrogen and showed pigments production only under phenylalanine-amended aerobic cultures. Stable isotope based precursor feeding studies indicated the blue pigment consists of 4-phenyl rings derived from L-phenylalanine. The purified blue pigment displayed characteristic visible-absorption and pH-dependent color variations. Precursor-feeding under altered growth conditions activated the plausible novel aromatic pigment production in strain JA2. CONCLUSION Our approach unraveled the previously unknown pigment synthesis in strain JA2 and demonstrated the potential of mining strategy in discovering the hidden secondary metabolite repertoire in microorganisms.
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Lu D, Xue L, Feng C, Jin Y, Wu C, Xie C, Gonzalez FJ, Wang G, Zhou Z. A systemic workflow for profiling metabolome and lipidome in tissue. J Chromatogr A 2018; 1589:105-115. [PMID: 30638710 DOI: 10.1016/j.chroma.2018.12.061] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2018] [Revised: 10/13/2018] [Accepted: 12/27/2018] [Indexed: 12/16/2022]
Abstract
Simple metabolome and lipidome sample preparation procedures involving two successive extractions using small pieces of tissue, and a subsequent metabolite identification (MetID) strategy were developed. The sample preparation can significantly circumvent incomplete analysis due to insufficient amounts of tissue as a result of splitting into several aliquots for multiple measurements, with advantages over the similar previously reported methods in metabolite coverage, extraction efficiency, method robustness and friendly experimental operation. A MetID strategy, based on the integration of MS information mining (including adduct ions, in-source CID, MS information from both ESI (+) and ESI (-), characteristic fragmentation ions (CFIs), constant neutral losses (CNLs) and multimers) and in silico MS simulation, was demonstrated. A large number of adduct ions (83 features), in-source CID (123 features), ESI (+/-) ionization (20 features), CFIs& CNLs (more than 120 features) and multimers (17 features) were mined by manually or in silico recognition/filtering, which provide the most suspicious structures for subsequent in silico MS simulation. The unknown features presented the same score distribution as the known (83 features) features with scores ≥25% (geomean score: 52%) and with satisfactory match for the main ions of interest. The MS/MS noise and fragment ions of coeluted quasi-molecular ions of interest are the main reason for the low score in the simulation. Manual check/evaluation is always suggested for the simulation with a score less than 50%. This strategy presents satisfactory performance with 2.5 times more metabolites structurally characterized compared with that of the traditional method based on accurate-mass-based MS and MS/MS library matching. This strategy would be useful for potentially identifying metabolites without available MS/MS information in the library.
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Affiliation(s)
- Dasheng Lu
- Shanghai Municipal Center for Disease Control and Prevention, 1380 Zhongshan West Road, Shanghai, 200336, China; School of Public Health/MOE Key Lab for Public Health, Fudan University, Shanghai, 200032, China; Laboratory of Metabolism, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Liming Xue
- Shanghai Municipal Center for Disease Control and Prevention, 1380 Zhongshan West Road, Shanghai, 200336, China
| | - Chao Feng
- Shanghai Municipal Center for Disease Control and Prevention, 1380 Zhongshan West Road, Shanghai, 200336, China
| | - Yu'e Jin
- Shanghai Municipal Center for Disease Control and Prevention, 1380 Zhongshan West Road, Shanghai, 200336, China
| | - Chunhua Wu
- School of Public Health/MOE Key Lab for Public Health, Fudan University, Shanghai, 200032, China
| | - Cen Xie
- Laboratory of Metabolism, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Frank J Gonzalez
- Laboratory of Metabolism, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Guoquan Wang
- Shanghai Municipal Center for Disease Control and Prevention, 1380 Zhongshan West Road, Shanghai, 200336, China.
| | - Zhijun Zhou
- School of Public Health/MOE Key Lab for Public Health, Fudan University, Shanghai, 200032, China.
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Gupta D, Mohammed M, Mekala LP, Chintalapati S, Chintalapati VR. iTRAQ-based quantitative proteomics reveals insights into metabolic and molecular responses of glucose-grown cells of Rubrivivax benzoatilyticus JA2. J Proteomics 2018; 194:49-59. [PMID: 30597313 DOI: 10.1016/j.jprot.2018.12.027] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2018] [Revised: 12/19/2018] [Accepted: 12/26/2018] [Indexed: 01/28/2023]
Abstract
Anoxygenic photosynthetic bacteria thrive under diverse habitats utilising an extended range of inorganic/organic compounds under different growth modes. Although they display incredible metabolic flexibility, their responses and adaptations to changing carbon regimes is largely unexplored. In the present study, we employed iTRAQ-based global proteomic profiling and physiological studies to uncover the adaptive strategies of a phototrophic bacterium, Rubrivivax benzoatilyticus JA2 to glucose. Strain JA2 displayed altered growth rates, reduced cell size and progressive loss of pigmentation when grown on glucose compared to malate under photoheterotrophic condition. A ten-fold increase in the saturated to unsaturated fatty acid ratio of glucose-grown cells indicates a possible membrane adaptation. Proteomic profiling revealed extensive metabolic remodelling in the glucose-grown cells wherein signal-transduction, selective-transcription, DNA-repair, transport and protein quality control processes were up-regulated to cope with the changing milieu. Proteins involved in DNA replication, translation, electron-transport, photosynthetic machinery were down-regulated possibly to conserve the energy. Glycolysis/gluconeogenesis, TCA cycle and pigment biosynthesis were also down-regulated. The cell has activated alternative energy metabolic pathways viz., fatty acid β-oxidation, glyoxylate, acetate-switch and Entner-Doudoroff pathways. Overall, the present study deciphered the molecular/metabolic events associated with glucose-grown cells of strain JA2 and also unraveled how a carbon source modulates the metabolic phenotypes. SIGNIFICANCE: Anoxygenic photosynthetic bacteria (APB) exhibit incredible metabolic flexibility leading to diverse phenotypes. They thrive under diverse habitat using an array of inorganic/organic compounds as carbon sources, yet their metabolic adaptation to varying carbon regime is mostly unexplored. Present study uncovered the proteomic insights of the cellular responses of strain JA2 to changing carbon sources viz. malate and glucose under photoheterotrophic conditions. Our study suggests that carbon source can also determine the metabolic fate of the cells and reshape the energy dynamics of APB. Here, for the first time study highlighted the plausible carbon source (glucose) mediated regulation of photosynthesis in APB. The study sheds light on the plausible cellular events and adaptive metabolic strategies employed by strain JA2 in presence of non-preferred carbon source. It also revealed new insights into the metabolic plasticity of APB to the changing milieu.
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Affiliation(s)
- Deepshikha Gupta
- Department of Plant Sciences, P.O. Central University, University of Hyderabad, Hyderabad 500046, India
| | - Mujahid Mohammed
- Department of Plant Sciences, P.O. Central University, University of Hyderabad, Hyderabad 500046, India
| | - Lakshmi Prasuna Mekala
- Department of Plant Sciences, P.O. Central University, University of Hyderabad, Hyderabad 500046, India
| | - Sasikala Chintalapati
- Bacterial Discovery Laboratory, Centre for Environment, IST, JNT University Hyderabad, Kukatpally, Hyderabad 500085, India
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Mekala LP, Mohammed M, Chinthalapati S, Chinthalapati VR. Pyomelanin production: Insights into the incomplete aerobic l-phenylalanine catabolism of a photosynthetic bacterium, Rubrivivax benzoatilyticus JA2. Int J Biol Macromol 2018; 126:755-764. [PMID: 30572055 DOI: 10.1016/j.ijbiomac.2018.12.142] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2018] [Revised: 12/13/2018] [Accepted: 12/16/2018] [Indexed: 02/06/2023]
Abstract
Rubrivivax benzoatilyticus JA2 is a metabolically versatile bacterium, thrives on a wide array of organic compounds under different growth modes. Though genomic insights revealed the aromatic compound catabolic potential of strain JA2 under anaerobic/aerobic conditions, the studies are largely restricted to anaerobic metabolism. The previous study on phenylalanine metabolism in strain JA2 indicated melanin-like pigment production under aerobic conditions; however, characterization of pigment and its biosynthetic pathway is not explored. The current study aims at the characterization of pigment and elucidation of its biosynthetic pathway. Strain JA2 utilized l-phenylalanine as source of nitrogen under anaerobic/aerobic conditions but not as a carbon source. Strain JA2 produced a brown-pigment under phenylalanine-amended aerobic conditions. Spectroscopic and physicochemical analysis identified the purified brown-pigment as a melanin. Further, the genomic insights revealed the presence of a complete set of genes related to pyomelanin synthesis. Identification of key metabolites l-tyrosine, 4-hydroxyphenylpyruvic acid and homogentisic acid and their respective enzyme activities further supports the pyomelanin synthesis. Moreover, the precursors feeding, pathway specific inhibitor studies confirmed the pyomelanin synthesis in strain JA2. Our study revealed an incomplete catabolism of phenylalanine; absence of ring cleavage gene, homogentisate dioxygenase leading to homogentisate accumulation thereby pyomelanin synthesis in strain JA2.
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Affiliation(s)
- Lakshmi Prasuna Mekala
- Department of Plant Sciences, School of Life Sciences, University of Hyderabad, Hyderabad 500046, India
| | - Mujahid Mohammed
- Department of Plant Sciences, School of Life Sciences, University of Hyderabad, Hyderabad 500046, India
| | - Sasikala Chinthalapati
- Bacterial Discovery Laboratory, Centre for Environment, IST, JNT University Hyderabad, Kukatpally, Hyderabad 500 085, India
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