Toprak ve su örneklerinden amilolitik bakteri ve mayaların izolasyonu, tanımlanmaları ve bazı enzimatik özelliklerinin belirlenmesi üzerine bir araştırma (original) (raw)

1993

Abstract

Bu calismada, bazi toprak ve su orneklerinden amilolitik bakteri ve mayalar izole edilerek, bunlarin amilaz enzimlerinin ozellikleri arastirilmistir. Calismalarda izole edilen 10 maya ve 49 bakteri izolatindan 17 bakterinin amilolitik aktivite gosterdigi anlasilmistir. Sivi ve kati ortamlarda yapilan amilolitik aktivite olcumlerinde: dogal sicak su ve toprak orneklerinden izole edilen bakterilerin, digerlerine kiyasla, daha fazla aktivite gosterdikleri ve yuksek aktivite gosteren izolatlarin cogunun Bacillus cinsine ait oldugu belirlenmistir. Sicak su kaynagindan izole edilen B. subtilis 5a-2 susunun; maya ozutu-pepton-nisasta besiyerinde (YPS Broth) 40. saatte 24 U/ml a-amilaz ve 32. saatte 13 U/ml ile en yuksek pullulanaz aktivitesine erismistir. Ayni bakterinin amilaz aktivitesine etkisi arastirilan karbohidratlardan, mono- ve disakkaritlerin onemli bir etkisibulunmazken, dekstrin' in en etkili karbohidrat oldugu saptanmis ve ortamda dekstrin kullanilmasi ile amilaz aktivitesi 36 u/ml'ye ulasmistir. Termostabilitesi ve sicaklik optimumu arastirilan Bacillus subtil is 5a- 2 a-amilazi; 50°C de en yuksek aktivite gostermis, 50 ve 90°C sicaklik araliginda aktivite degeri yaklasik %90'in ustunde bulunmustur. Pullulanaz ise 60°C 'de en yuksek aktiviteye erismis olup 60 ve 90°C sicaklik arali ginda aktivite degeri yaklasik %95'in ustunde bulunmustur. Sicaklik stabilitelerinin saptanmasi amaciyla 100CC deki su banyosunda 2 saat inkubasyon sonunda; a-amilaz aktivitesinde %23, pullulanaz aktivitesinde ise % 5 azalma olmustur. Ayni bakterinin a-amilazinin pH 5 ve pullulanazinin pH 4-6 arasinda maksimum aktivite gosterdigi saptanmistir. Elde edilen ham enzim ekstrakti +4°C 'de 4 gun bekletildiginde toplam aktivitede % 5 'lik bir azalma gozlenmistir. Abstract In this study, amylolytic yeasts and bacteria strains were isolated and identified from different soil and water samples and determined some specifications of their amylolytic enzymes. From the samples, 10 yeasts and 49 bacteria strains were isolated, but only 17 bacteria showed amylolytic activity. Isolated amylolytic bacteria were clasified according to their total amylolytic activity on a liquide and a solid media. As a result, a Bacillus subtilis 5a-2 from hot spring sample and some other Bacillus strains from soil showed the highest activity. Hot-spring isolate, Bacillus subtilis 5a- 2 showed 24 U/ml a-amylase activity at 40. hours and 13 U/ml pullulanase activity at 32. hours as it is maximum on the YPS Broth.IV The effects of different C-sources on amylase activity were tested and dextrin was found to be the most effective carbohyrates with 36 U/ml of total activity. Thermostability and optimum temperature of a-amylase of Bacillus subtil is 5a-2 was determined. It was shown that the highest activity at 50°C and between 50°C-90°C the activity was as high as over 90% approximately. The pullula- nase activity has a maximal at 60°C and between 60°-90°C the activity was over 95% approximately, a-amylase has shown an activity of 77% and pullulanase 95 % at the end of incubation for 2 hours in a water bath of 100 °C. Optimum pH was 5 for a-amylase and pH 4-6 for pullulanase. Crude enzyme solution lost 5 % of their total amylase activity after 4 days at +4°C.

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