Enzymatic studies on some fungi isolated from the mountain honey
Eman Karam Abd El-Hmeed El -Saeed;
Abstract
Two new fungal honey isolates were identified based on morphological characterization and 18S rDNA sequence analysis. They were named as Aspergillus niger EM77 (KF774181) and Aspergillus awamori EM66 (KF774180). The validation of these novel species was supported further by its unique randomly amplified polymorphic DNA PCR patterns (RAPD). Since, the RAPD referred to 51 % coincidence between both isolates and showed different RAPD patterns between the references and the honey isolates. In RAPD-PCR analysis by using 10 primers, different reactions were generated from both fungal isolates. Aspergillus niger EM77 (KF774181) and Aspergillus niger reference isolated from soil as reference. According to these results, the RAPD technique indicated coincidence between Aspergillus niger and its soil isolate as reference equal 58%, and 50% in case of Aspergillus awamori.
The optimum conditions for the growth of both honey isolates were studied. The best aeration condition was achieved at 250 ml Erlenmeyer flask. The maximal fungal growth was obtained at 2ml inoculum, 30ºC and pH 7. The most favorable carbon and nitrogen sources were mannose and casein, respectively. The effect of NaCl concentrations was also studied and these referred to the halotolerant feature of both isolates. Both fungal strains showed strong antimicrobial activity against Candida albicans, C. pseudotropicalis and Pseudomonas species. The reducing power assay reported 82% and 83% antioxidant activity of Aspergillus niger EM77 (KF774181) and Aspergillus awamori EM66 (KF774180), respectively.
The aflatoxins and ocratoxins production verification revealed that both isolates had negative results. Both new fungal honey isolates showed relatively similar enzymatic activities. The honey strain (Aspergillus niger EM77) was a good halophilic invertase producer in the presence of wheat bran as the sole carbon and nitrogen source (114.6 U/g) and solid state fermentation technique. Different parameters have influenced the enzyme productivity such as pH, temperature, incubation period, nitrogen and carbon sources. The optimum pH, temperature, and incubation period for enzyme production were pH 5.5, 30˚C and 72h. The best carbon source for invertase production was sucrose (144.4 U/g) and (NH4)2SO4 was the ideal nitrogen source (158.21 U/g). Among different metal ions, MnSO4 enhanced the enzyme productivity to 183.38U/g. The enzyme was successfully precipitated by ethyl alcohol at (40-80%). The partially purified enzyme was successfully entrapped in polyvinyl alcohol (PVA) sponge shielded with agar layer and achieved 71% immobilization yield. The optimum conditions for free and immobilized form were 15 min. incubation period, acidic media pH 5 and 29.8 mg/ml protein concentration mg/ml. Immobilized enzyme was reused 12 times with 29% activity loss.
The optimum conditions for the growth of both honey isolates were studied. The best aeration condition was achieved at 250 ml Erlenmeyer flask. The maximal fungal growth was obtained at 2ml inoculum, 30ºC and pH 7. The most favorable carbon and nitrogen sources were mannose and casein, respectively. The effect of NaCl concentrations was also studied and these referred to the halotolerant feature of both isolates. Both fungal strains showed strong antimicrobial activity against Candida albicans, C. pseudotropicalis and Pseudomonas species. The reducing power assay reported 82% and 83% antioxidant activity of Aspergillus niger EM77 (KF774181) and Aspergillus awamori EM66 (KF774180), respectively.
The aflatoxins and ocratoxins production verification revealed that both isolates had negative results. Both new fungal honey isolates showed relatively similar enzymatic activities. The honey strain (Aspergillus niger EM77) was a good halophilic invertase producer in the presence of wheat bran as the sole carbon and nitrogen source (114.6 U/g) and solid state fermentation technique. Different parameters have influenced the enzyme productivity such as pH, temperature, incubation period, nitrogen and carbon sources. The optimum pH, temperature, and incubation period for enzyme production were pH 5.5, 30˚C and 72h. The best carbon source for invertase production was sucrose (144.4 U/g) and (NH4)2SO4 was the ideal nitrogen source (158.21 U/g). Among different metal ions, MnSO4 enhanced the enzyme productivity to 183.38U/g. The enzyme was successfully precipitated by ethyl alcohol at (40-80%). The partially purified enzyme was successfully entrapped in polyvinyl alcohol (PVA) sponge shielded with agar layer and achieved 71% immobilization yield. The optimum conditions for free and immobilized form were 15 min. incubation period, acidic media pH 5 and 29.8 mg/ml protein concentration mg/ml. Immobilized enzyme was reused 12 times with 29% activity loss.
Other data
| Title | Enzymatic studies on some fungi isolated from the mountain honey | Other Titles | دراسات إنزيمية على بعض الفطريات المعزولة من العسل الجبلى | Authors | Eman Karam Abd El-Hmeed El -Saeed | Keywords | Enzymes- Fungi- Honey- Isolation-Identification - Immobilization | Issue Date | 2014 |
Recommend this item
Similar Items from Core Recommender Database
Items in Ain Shams Scholar are protected by copyright, with all rights reserved, unless otherwise indicated.