Team:Hong Kong JSS/Basic Part
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Team:Hong Kong JSS/Basic Part
Hong Kong JSS
Laccase coding sequence from Trametes versicolor isolate K4 (GenBank KR492189.1).
Laccase is a multicopper oxidase found in various organisms, such as plants and fungi. Laccase catalyzes the oxidation of phenol groups in aromatic organic substances. Laccase has a wide range of applications, such as melanin production, lignin degradation, and lacquer synthesis. In recent years, laccase produced by some fungal species has also been reported to be involved in the bio-degradation of polyvinyl chloride (PVC) plastic in laboratory conditions [1]. Thus, it may also be a solution to the problem of micro-plastic waste pollution.
In our project, we focused on the aflatoxin B1 degrading ability of laccase.
Aflatoxin (AF) is a family of carcinogenic toxins produced by Aspergillus sp.. According to the World Health Organization (WHO), 25% of food crops are destroyed due to aflatoxin contamination each year. About 5 billion people are at risk of chronic AF exposure and more than 80% of them will develop AF-related diseases such as hepatocellular carcinoma and liver failure [2]. Among all AF, aflatoxin B1 (AFB1) is considered the most potent and chronic [3].
Different groups have demonstrated the effectiveness of AFB1 degradation by using native and recombinant laccase [4]. Among all the laccase produced by different species reviewed, laccase produced by Trametes versicolor (white rot) was found to be the most effective in AFB1 degradation [5]. Thus, our team proposes to heterogeneously express this tvLac in probiotic E. coli and to see if it can be a plausible measurement to degrade AFB1 in food and act as a food preservative for Aspergillus sp. infection.
This is the design of a phase I project design.
[1] Sumathi T, Viswanath B, Sri Lakshmi A, SaiGopal DV. Production of Laccase by Cochliobolus sp. Isolated from Plastic Dumped Soils and Their Ability to Degrade Low Molecular Weight PVC. Biochem Res Int. 2016;2016:9519527. doi: 10.1155/2016/9519527. Epub 2016 May 12. PMID: 27293894; PMCID: PMC4880699.
[2] Organization WH. aflatoxin. Manuf Comput Solut. 2000;6(8):20-3
[3] Okwara, P. C., Afolabi, I. S., & Ahuekwe, E. F. (2021). Application of laccase in aflatoxin B1 degradation: A Review. IOP Conference Series: Materials Science and Engineering, 1107(1), 012178. https://doi.org/10.1088/1757-899x/1107/1/012178
[4] Alberts, J. F., Gelderblom, W. C. A., Botha, A., & van Zyl, W. H. (2009). Degradation of aflatoxin B1 by fungal laccase enzymes. International Journal of Food Microbiology, 135(1), 47–52. https://doi.org/10.1016/j.ijfoodmicro.2009.07.022
[5] Verheecke, C., Liboz, T., & Mathieu, F. (2016). Microbial degradation of aflatoxin B1: Current status and future advances. International Journal of Food Microbiology, 237, 1–9. https://doi.org/10.1016/j.ijfoodmicro.2016.07.028
F420H2-dependent reductase (FDR) is a family of enzymes produced by microorganisms that catalyze the reduction of aflatoxin and lead to their spontaneous degradation and produce a non-toxic product [1].
This enzyme can be found in bacterial strains such as Mycobacterium sp., Arthrobacter sp., and Pseudomonas sp.. The native function of the enzymes in these organisms is for methanogenesis [2], antibiotic resistance [3], and other redox-related metabolic activities. Nevertheless, it was believed that FDR’s native functions do not involve aflatoxin degradation since the above bacterial species seldom exist near any source of aflatoxin. Thus, it was a novel finding that FDRs are involved in the degradation of aflatoxin and there was considerable interest in the study of FDRs properties recently [1].
Among all species reviewed, Mycobacterium smegmatis was found to have the FDRs with the highest activity [4]. And from all the loci of the two FDR families (FDR-A and FDR-B) in M. smegmatis, FDR-A at locus MSMEG_5998 was found to have the highest enzymatic activity in degrading AFB1, AFB2, and AFG1 [1]. Therefore, we hypothesize that FDR-A would also show the high efficiency of AFB1 degradation in our project setting.
Literature showed that adding co-factors F420H2 can enhance the enzymatic activity of the FDR-A, so in our detoxifying spray, we planned to add the F420H2 cofactor with anti-oxidants into the buffer and thus increasing the efficiency of AFB1 degradation in our product.
Aflatoxin (AF) is a family of carcinogenic toxins produced by Aspergillus sp.. According to the World Health Organization (WHO), 25% of food crops are destroyed due to aflatoxin contamination each year. About 5 billion people are at risk of chronic AF exposure and more than 80% of them will develop AF-related diseases such as hepatocellular carcinoma and liver failure [5]. Among all AF, aflatoxin B1 (AFB1) is considered the most potent and chronic [6].
This is the design of a phase I project design.
[1] Taylor, M. C., Jackson, C. J., Tattersall, D. B., French, N., Peat, T. S., Newman, J., Briggs, L. J., Lapalikar, G. V., Campbell, P. M., Scott, C., Russell, R. J., & Oakeshott, J. G. (2010). Identification and characterization of two families of F420H2-dependent reductases from mycobacteria that catalyse aflatoxin degradation. Molecular Microbiology, 78(3), 561–575. https://doi.org/10.1111/j.1365-2958.2010.07356.x
[2] Graham, D.E., and White, R.H. (2002) Elucidation of methanogenic coenzyme biosyntheses: from spectroscopy to genomics. Nat Prod Rep 19: 133–147.
[3] Hasan, M.R., Rahman, M., Jaques, S., Purwantini, E., and Daniels, L. (2010) Glucose-6-phosphate accumulation in mycobacteria: implications for a novel F420-dependent anti-oxidant defense system. J Biol Chem 285: 19135– 19144.
[4] Verheecke, C., Liboz, T., & Mathieu, F. (2016). Microbial degradation of aflatoxin B1: Current status and future advances. International Journal of Food Microbiology, 237, 1–9. https://doi.org/10.1016/j.ijfoodmicro.2016.07.028
[5] Organization WH. aflatoxin. Manuf Comput Solut. 2000;6(8):20-3
[6] Okwara, P. C., Afolabi, I. S., & Ahuekwe, E. F. (2021). Application of laccase in aflatoxin B1 degradation: A Review. IOP Conference Series: Materials Science and Engineering, 1107(1), 012178. https://doi.org/10.1088/1757-899x/1107/1/012178