الفهرس 
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Abstract
Aflatoxicosis is a type of poisoning caused due to the consumption of ubiquitous carcinogens called aflatoxins which are produced by toxigenic Aspergillus species and contaminate food and agricultural commodities extensively posing major threats to both human health and livestock productivity, especially in the poultry industry. Several decontamination solutions were proposed, but biodegradation methods seemed to be the most attractive solution owing to its specificity and eco-friendliness.
Our study aimed to screen and identify aflatoxin degrading bacteria using both metagenome based methods and traditional methods. Ten bacterial isolates were screened using coumarin as a sole carbon source in media (traditional method), their degradation rates ranged between (25-100%) when tested against AFB1, AFB2, AFG1 & AFG2 using HPLC analysis. Biochemical and molecular identification of these isolates revealed that they belong to four genera; Bacillus (6), Pseudomonas (2), Enterococcus (1) and Stenotrophomonas (1) including Pseudomonas fluorescens SZ1 that showed the highest degradation rate (" ~ "100% to all aflatoxins) after incubation at 37 °C for 72 hrs. in liquid media. While the Metagenome based analysis (microbiome analysis) of 4 environmental samples (2 soil & 2 feed) associated with variable aflatoxin degradation rates revealed that the major taxa usually associated with AF contamination are Proteobacteria, Firmicutes, Bacteroidetes, Actinobacteria and Cyanobacteria. On the genus level, Bacillus spp were identified as significantly dominant bacteria in active feed degrading samples while family Streptophyta were significantly important in active soil samples. New key microbes usually ignored by conventional culture dependent techniques were present in high AF degrading samples using metagenome based technology, such as Jeotgaliococcus spp, Halomonus spp, lysobacter and Streptophyta. Additionally in our study laccase and lactonase genes for Bacillus spp (model) were screened in both culturable isolates and metagenomic samples using primers developed by our team. Insilco analysis and docking of both laccase and lactonase genes in Bacillus haynesii showed promising interactions of both proteins against aflatoxins. Our study suggests biocontrol potential of several different species isolated from poultry farms; B. haynesii, B. licheniformis, B. tequilensis, B. subtilis, B. amyloliquefaciens, Pseudomonas fluorescens, Enterococcus casseliflavus, and Stenotrophomonas maltophilia and other important genera weather culturable or not as Jeotgaliococcus spp, Halomonus spp, lysobacter highlighting the importance of metagenomics in screening novel bacteria and catabolic genes that can be used in biotechnology. The results also proposed Pseudomonas fluorescens SZ1 as an excellent candidate for bioremediation of aflatoxin in feed matrices while our Insilco analysis revealed that purified products (lactonase & laccase) from B. haynesii can be excellent candidates for biotechnology applications.