Aspergillus Section Flavi Gelişimine Ve Toksin Üretimine Süre-sıcaklık Etkisinin İncelenmesi
Aspergillus Section Flavi Gelişimine Ve Toksin Üretimine Süre-sıcaklık Etkisinin İncelenmesi
Dosyalar
Tarih
21.06.2010
Yazarlar
Esen, Aysu Dalgıç
Süreli Yayın başlığı
Süreli Yayın ISSN
Cilt Başlığı
Yayınevi
Fen Bilimleri Enstitüsü
Institute of Science and Technology
Institute of Science and Technology
Özet
Küf gelişimi ve mikotoksin üretimi pek çok çevresel faktörden etkilenmektedir. Aspergillus flavus ve Aspergillus parasiticus üzerinde bu etkilerin incelenmesi, bu küflerin pek çok gıdada bulunmaları ve en toksik mikotoksin grubu olan aflatoksinleri üretmeleri sebebiyle büyük önem taşımaktadır. Bu çalışmada A. flavus ve A. parasiticus izolatlarının gelişimi ve mikotoksin üretimi üzerine süre-sıcaklık etkisi katı besiyerinde incelenmiştir. Küf izolatları farklı sürelerde (1, 2, 3, 4 saat) , farklı sıcaklık derecelerine (30°C, 35°C, 40°C, 45°C) maruz bırakılmış ve daha sonra 25°C’lik etüve alınarak 7 gün boyunca inkübe edilmiştir. Küf gelişimi, 24 saat aralıklarla koloni çapı ölçülerek belirlenmiş ve günlük olarak değerlendirilmiştir. Aflatoksin üretimi üzerine süre-sıcaklık etkisi, 7 günlük inkübasyon sonunda HPLC analizleri ile saptanmıştır. Elde edilen veriler, 25°C’de inkübe edilen kontrol grubu ile karşılaştırılmıştır. İnkübasyonun belirli bir aşamasından sonra, 40 ve 45°C’lik uygulamaların A. flavus ve A. parasiticus gelişiminde azalmaya, 30 ve 35°C’lik uygulamaların yalnızca A. parasiticus gelişiminde artışa sebep olduğu belirlenmiştir. Kontrol grubunda aflatoksin B1 üretiminin maksimum düzeyde olduğu, süre-sıcaklık uygulamaları ile aflatoksin B1 üretiminin azaldığı saptanmıştır. İzolatların aflatoksin B2 üretiminde izolatlar arası farklılık görülmüş, süre-sıcaklık uygulamasına bağlı olarak toksin miktarında kontrol grubuna göre artış veya azalma belirlenmiştir. 40 ve 45°C’lik uygulamarın aflatoksin G1 üretiminde artışa neden olduğu saptanmıştır. A. parasiticus izolatının aflatoksin G2 üretiminde ve toplam aflatoksin miktarında süre-sıcaklık uygulamalarının istatistiksel açıdan bir farklılığa sebep olmadığı belirlenmiştir.
Fungal growth and mycotoxin production are influenced by a variety of extrinsic factors. Investigating these factors on Aspergillus flavus and Aspergillus parasiticus has a great importance because their presence in lots of foods and their ability to produce aflatoxins which are the most carcinogenic mycotoxins. In this study, effect of different time-temperature combinations on growth and mycotoxin production of A.flavus and A.parasiticus isolates was evaluated in solid media. The isolates were incubated at 25°C for 7 days after they were exposed to different time (1, 2, 3 and 4 hours)-temperature (30°C, 35°C, 40°C, 45°C) effects. Fungal growth was examined daily by measuring the diameter of the colonies.The effect of time-temperature on mycotoxin production is evaluated by HPLC with the isolates incubated for 7 days. Results were compared with the control groups incubated at 25°C. It was observed that, after a definite period of incubation, treatments at 40 and 45°C cause reduction in growth whereas treatments at 30 and 35°C improves only A. parasiticus growth. The isolates incubated at 25°C for 7 days produce aflatoxin B1 at maximum levels, toxin production decreases by time-temperature effect. The difference in behaviour of aflatoxin B2 production was seen between isolates, the decrease or increase in the amount was observed compared with the control groups. It was found that treatments at 40 and 45°C improves aflatoxin G1 production and statistically, time- temperature effects do not cause any difference on aflatoxin G2 production and on total aflatoxin concentration of A. parasiticus.
Fungal growth and mycotoxin production are influenced by a variety of extrinsic factors. Investigating these factors on Aspergillus flavus and Aspergillus parasiticus has a great importance because their presence in lots of foods and their ability to produce aflatoxins which are the most carcinogenic mycotoxins. In this study, effect of different time-temperature combinations on growth and mycotoxin production of A.flavus and A.parasiticus isolates was evaluated in solid media. The isolates were incubated at 25°C for 7 days after they were exposed to different time (1, 2, 3 and 4 hours)-temperature (30°C, 35°C, 40°C, 45°C) effects. Fungal growth was examined daily by measuring the diameter of the colonies.The effect of time-temperature on mycotoxin production is evaluated by HPLC with the isolates incubated for 7 days. Results were compared with the control groups incubated at 25°C. It was observed that, after a definite period of incubation, treatments at 40 and 45°C cause reduction in growth whereas treatments at 30 and 35°C improves only A. parasiticus growth. The isolates incubated at 25°C for 7 days produce aflatoxin B1 at maximum levels, toxin production decreases by time-temperature effect. The difference in behaviour of aflatoxin B2 production was seen between isolates, the decrease or increase in the amount was observed compared with the control groups. It was found that treatments at 40 and 45°C improves aflatoxin G1 production and statistically, time- temperature effects do not cause any difference on aflatoxin G2 production and on total aflatoxin concentration of A. parasiticus.
Açıklama
Tez (Yüksek Lisans) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 2010
Thesis (M.Sc.) -- İstanbul Technical University, Institute of Science and Technology, 2010
Thesis (M.Sc.) -- İstanbul Technical University, Institute of Science and Technology, 2010
Anahtar kelimeler
Aflatoksin,
A. flavus,
A. parasiticus,
Sıcaklık,
Aflatoxin,
A. flavus,
A. parasiticus,
Temperature