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In the present study, 120 yeast isolates from different sources (active sludge, soil, and wastewater samples obtained from petroleum refinery and soil contaminated by petroleum) were obtained. The yeast isolates were screened for lipase production and twelve of the isolates (D3, D17, D24, D27, D30, D38, D40, D42, D44, D46, D56, and D57) exhibited lipase activity. Molecular characterization of the yeasts showing the lipase production was performed with RFLP of ITS1-5.8S-ITS2 and 18S rRNA and sequence analysis of D1/D2 domain of 26S rRNA. The 26S rRNA sequencing revealed that four new strains, D38, D40, D44 and D57 identified as Rhodotorula slooffiae, Candida davisiana, Cryptococcus diffluens, and Cryptococcus uzbekistanensis, respectively, are lipase producing yeast species. This study is the first report showed lipase production by these species. The other lipase producing strains identified as Candida parapsilosis (D3), Rhodotorula muciloginosa (D17 and D42), Cryptococcus albidus (D24, D27, D30, and D56), and Wickerhamomyces anomalus (D46).

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Postharvest diseases of fruits and vegetables result in critical losses

Mikrobiyal enzimler önemli bir biyoteknolojik araçlardır. Birçok biyolojik ve kimyasal reaksiyonda rol almaktadırlar ve çeşitli endüstrilerdeki farklı alanlarda kendilerine önemli sayılabilecek bir yer edinmişlerdir. Mikrobiyal enzimler arasından lipaz ve proteazlar, bu grubun önemli birer üyeleridirler. Dolayısıyla, bu enzimleri üreten mikroorganizmaların seçimi ve ürettikleri enzimlerin karakteristiklerinin saptanması, pek çok araştırmacıyı bu alanda çalışmaya teşvik etmektedir. Bu çalışmada, Karadeniz deniz sediment örneklerinden izole edilmiş aktinobakteri suşlarının hücre dışı lipaz ve proteaz enzim üretim kapasitelerinin belirlenmesi ve pH ile sıcaklık kararlılıklarının saptanması amaçlanmıştır. Çalışmadan elde edilen sonuçlar değerlendirildiğinde, bu organizmaların iyi birer lipaz ve proteaz enzim üreticisi ve bunların enzimlerinin geniş birer pH ve sıcaklık kararlılıklarına sahip oldukları saptanmıştır.

Alkaline enzymes obtained from microbial sources find numerous applications in different industrial processes and have commercial value. The aims of the study were to investigate the potential of two actinobacteria (Streptomyces sp. K16 and K19) isolated from Black Sea sediments to produce industrial alkaline enzymes and to characterize their activities under different chemical and physical conditions. The optimal incubation time for the production was determined as 96 h, and by using two actinobacteria respectively 7.91 and 7.94 U mL-1 of activities for amylases, 0.55 and 0.82 U mL-1 for lipases and 3.07 and 2.34 U mL-1 for proteases were obtained. The optimal pH and temperature values for the enzymes were found to be pH 8.0 and 37°C. All the enzymes exhibited stability in different quantities after the incubation at pH values ranging from 3.0 and 10.0 for 2 h. On the other hand, the lipases remained stable up to 50°C although the amylases and proteases showed stability in varying ratios after 2 h incubation under the tested temperatures. In the light of the findings, the actinobacteria and their enzymes are thought to have potential for further studies.

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