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• Isolation and Screening of Extracellular Phytase Producing Bacteria

  Nguyen Van Giang, Tran Thi Dao, Dinh Quang Hieu, Dang Ngoc Bich, Tran Thi Cam Tu, Bui Thi Hang

  Date Received: 15-05-2013 / Date Accepted: 16-08-2013 / Date Published: 13-06-2025

   Abstract PDF (VIETNAMESE)

  Phytases are enzymes hydrolyzing phytic acid to release inorganic phosphate and myo-inositol.Phytase produced by microorganisms have potential industrial applications. The supplementation of animal feed with phytases reduces the cost of diets by removing or reducing the need for supplemental inorganic phosphate and increases the bioavailability of phosphorous in monogastric animals. In this study, soil close to pig and chicken farms at Ha Noi university of agriculture was used as a source material for isolating phytase producing bacteria. On PSM medium, six bacterial isolates having potential phytase production were isolated. Among these, M4 isolate showed maximum phytase activity. M4 isolate was biochemically characterized as Bacillus spp.

  DOI: https://doi.org/10.31817/tckhnnvn.2013.11.4.

• Assessing the Effective of Feed Added with Mixed of Enzymeto Culture Rainbow Trout (Oncorhynchus mykiss) at the First Commercial Stage

  Nguyen Thi Trang, Do Huu Quynh, Tran Dinh Luan

  Date Received: 17-04-2012 / Date Accepted: 02-06-2012

   Abstract PDF (VIETNAMESE)

  Adding enzyme in feed in order to increase food digestibility, reducing pollution and increasing economical efficiency are being focused in fish nutrition research in recently. The rainbow trout at the size from 150 g to 450 g were cultured to evaluate the effect of the addition of enzymes to the feed for rainbow trout. This study used 3 different feed formulations: feed without enzyme supplement (CT1), feed was added with mixed of 6000 IU amylase, 2000 IU protease and 2000 IU phytase/1 kilogram (CT2) and a feed control RAISIO - Finland (CT3). The results shown that the survival rates are more than 97%. The Average Daily Growth rate (g/fish/day) of CT1 was 3.18, CT2 was 3.48, CT3 was 3.65 and significant difference (P < 0.05). The Food Comsumption ranged from 343 to 360 g of feed/fish and there was no significant difference between the three feed formulars (P > 0.05). The Food Conversion Ratio ranged from 1.12 to 1.31 and there was no significant different between CT2 and CT3  (P > 0.05). The initial research results show that food added enzyme is better than it did not added enzyme and can replace for imported feed to culture rainbow trout at the size of 150-450 g.

• Phân lập và khảo sát sự biểu hiện của promoter của gen phytase từ bacillus licheniformis DSM13

  Nguyen Thanh Trung, Nguyen Minh Trung, Nguyen Huy Thuan, Trinh Thanh Trung, Nguyen Quoc Trung, Trinh Thi Thu Thuy, Nguyen Hoang Anh

  Date Received: 20-09-2017 / Date Accepted: 25-03-2017 / Date Published: 06-08-2025

   Abstract PDF (VIETNAMESE)

  Phytase là một họ enzyme thủy phân cơ chất phytate để giải phóng ra phosphate vô cơ cùng các sản phẩm trung gian myo-inositol phosphate. Gene mã hóa enzyme phytase (phyL) ở Bacillus licheniformis DSM13 cảm ứng biểu hiện mạnh trong các điều kiện thiếu hụt phosphate. Trong nghiên cứu này, chúng tôi thiết kế vector biểu hiện sử dụng promoter của gene phyL để điều khiển sự biểu hiện của gen xynA (mã hóa enzyme xylanase). Hoạt tính promoter phyL được xác định thông qua mức độ biểu hiện của protein XynA. Chủng tái tổ hợp được nuôi cấy trong điều kiện môi trường không có hoặc có bổ sung phytate ở các nồng độ khác nhau. Kết quả cho thấy hoạt động của promoter phyL được cảm ứng mạnh khi nồng độ cơ chất phytate bổ sung vào ở giá trị £ 5 mM. Ngoài ra, thí nghiệm phân tích sinh trưởng của vi khuẩn trong môi trường có bổ sung phytate chỉ ra rằng phytate là một nguồn phosphate thay thế quan trọng giúp cho vi khuẩn B. licheniformis vượt qua các điều kiện đói phosphate.

  DOI: https://doi.org/10.31817/tckhnnvn.2017.15.3.