Mikrobiol. Z. 2020; 82(2):14-21. Ukrainian.
doi: https://doi.org/10.15407/microbiolj82.02.014

Keratinolytic Activity of Antarctic Bacterial Strains

K.V. Avdiyuk1, L.D. Varbanets1, A.E. Berezkina2,3, A.Yu. Utevsky2,3

1Zabolotny Institute of Microbiology and Virology, NAS of Ukraine
154 Akad. Zabolotny Str., Kyiv, 03143, Ukraine

2National Antarctic Scientific Center, MES of Ukraine
16 Taras Shevchenko Blvd., Kyiv, 01601, Ukraine

3Karazin Kharkiv National University
Svobody Sq., 4, Kharkiv, 61022, Ukraine

Every year, millions of tons of keratin-containing raw materials, such as feathers, wool, hair, etc., are released into the environment as a by-product of agro-processing, which are difficult to degrade by conventional proteases such as pepsin, trypsin and papain. Therefore, the search for effective producers of keratinolytic enzymes that can cleave these inaccessible proteins is a relevant topic of research. Aim. To investigate caseinolytic and keratinolytic activity of bacterial isolates obtained from soft tissues and intestinal tube of Nacella concinna gastropod mollusks, selected near the Ukrainian Antarctic Akademik Vernadsky station. Methods. The objects of study were 21 bacterial isolates. The cultures were grown on 4 types of liquid nutrient media, which were different in carbon and nitrogen sources, as well as the presence or absence of NaCl. Enzymatic activity was determined in the liquid culture supernatant. Fat free feathers and casein were used as substrates to determine the keratinolytic and caseinolytic activity. Results. The highest level of caseinolytic activity were demonstrated by 13c/6 and 15c/1 bacterial isolates obtained from the intestinal tube of mollusks at a temperature of not only 19°C (0.082 U/ml and 0.027 U/ml respectively), but also at 28°C (0.074 U/ml and 0.064 U/ml respectively). The highest levels of keratinolytic activity at 19°C were found in 16b/2, 17b/1 and 10b/2 cultures (15 U/ml, 14 U/ml and 8 U/ml respectively) isolated from soft tissues, and 9c/3 and 5c/1 (14 U/ml, 7 U/ml respectively) cultures isolated from the intestinal tube of mollusks. At 28°C, 6c/1 and 2b/5 bacterial isolates obtained from the intestinal tube and soft mollusk tissues had keratinolytic activity at 9 U/ml and 8 U/ml, respectively. Most often keratinolytic activity was detected in cultures isolated from mollusks inhabiting Skua Creek Strait (13c/6, 15c/1, 16b/2 and 17b/1) and Meek Channel (2b/5, 5c/1, 6c/1, 9c/3). Conclusions. Most cultures synthesized enzymes with keratinolytic activity at 28°C (from 1 to 9 U/ml), but at 19°C the level of this activity was higher (from 1 to 15 U/ml). It is shown that only 5 bacterial isolates, when grown at 28°C, showed caseinolytic activity at the level from 0.011 to 0.074 U/ml, while a large number of cultures (10) had this activity at 19°C (from 0.01 to 0.082 U/ml).

Keywords: bacterial isolates, mollusks (Nacella concinna), Antarctica, keratinolytic activity, caseinolytic activity.

Full text (PDF, in Ukrainian)

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