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. 2020 Apr 28:13:1178636120913280.
doi: 10.1177/1178636120913280. eCollection 2020.

Microbial Bioremediation of Feather Waste for Keratinase Production: An Outstanding Solution for Leather Dehairing in Tanneries

Mursheda Akhter  1 , Lolo Wal Marzan  1 , Yasmin Akter  1 , Kazuyuki Shimizu  2   3
Affiliations

Microbial Bioremediation of Feather Waste for Keratinase Production: An Outstanding Solution for Leather Dehairing in Tanneries

Mursheda Akhter et al. Microbiol Insights. .

Abstract

In leather industries and tanneries, large amount of wastes has been disposed; which polluting water, soil, and atmosphere and causing serious human health problems. In particular, chemical dehairing process of leather industries produces fair amount of toxic wastes. It is, thus, urgently needed to use alternative processes free from pollution. As more than 90% of keratin is contained in feather, it is desirable to develop bioremediation process using keratinolytic microorganisms. In the present investigation, therefore, we first identified Bacillus cereus and Pseudomonas sp. to be able to produce keratinase. Then, the optimization was performed to maximize the keratinase activity with respect to cultivation temperature, pH, and incubation time. Moreover, the effects of metal ions and various substrates on keratinase activity were also investigated. The result indicates that keratinase activity became maximum at 50°C for both strains, whereas the optimal pH was 10.0 for B. cereus and 7.0 for Pseudomonas sp. The highest keratinase activity of 74.66 ± 1.52 U/mL was attained by B. cereus, whereas 57.66 ± 2.52 U/mL was attained by Pseudomonas sp. Enzymatic dehairing efficiency of leathers was also compared with chemical dehairing (Na2S and CaO), where complete dehairing was achieved by treating them with crude keratinase. Partial enzyme purification was performed by acetone precipitation. Batch cultivation of B. cereus using 1 L fermentor indicates a potential candidate for large-scale keratinase production. Thus, keratinase enzyme by degrading poultry wastes (feather) can be an alternative approach to chemical dehairing in leather industries, thus preventing environmental pollution through bioremediation.

Keywords: Bacillus cereus; Pseudomonas sp.; bioremediation; fermentation; keratinase; leather dehairing.

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Conflict of interest statement

Declaration of conflicting interests:The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Figures

Figure 1.
Figure 1.
(A) Plate assays of 7 pure isolates. (B) Growth of isolates (SA, SJ) on FMA (Feather Meal Agar).
Figure 2.
Figure 2.
Electrophoretic (1% agarose) separation of 16S rDNA gene of different isolates. M indicates 1 kb DNA marker; L1-L2, L3-L4 show bands of SJ and SA, respectively; P1, P2 for positive control (SJ and SA); and N for negative control, respectively.
Figure 3.
Figure 3.
Phylogenetic tree construction. Phylogenetic tree showing relationship between formula image Bacillus cereus strain AIMST 4. Ca.8 and formula image Pseudomonas sp. B7 16S with other selected members of B. cereus and Pseudomonas sp.
Figure 4.
Figure 4.
Partial characterization of crude keratinase activity (enzyme-substrate reaction). Effects of (A) temperature, (B) pH, (C) reaction time, (D) metal ions, and (E) substrates.
Figure 5.
Figure 5.
Standard graph of Folin-Lowry assay.
Figure 6.
Figure 6.
Comparative study of dehairing assay (field trial).
See this image and copyright information in PMC

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