Lime and sulphide-free dehairing of animal skin using collagenase-free alkaline protease from Vibrio metschnikovii NG155. National Library of Medicine 2010. https://doi.org/1010.1016/j.jbiotec.2015.07.007, Successful, safe and effective removal of earwax from the external ear canal, Keratinases present natural alternative to the use of acids for corn and callus removal, Keratoclean Hydra PB, PURE 100 Keratinase, Acne is caused by blockage of sebaceous glands in the presence of large quantities of keratin, therefore keratinases can be used for successful treatment, Keratoclean Sensitive PB, Keratopeel PB, Keratinase product improves the feed ratio and has a positive effect on chicken body mass, Enzyme product reduces cost of cooking and temperature processing of feather, therefore increasing the digestibility and nutritional value of feed, Effective decontamination of medical instruments from prions. In addition, proteomic and transcriptomic tools give us an information on the expression of target genes in specific conditions and explore their mechanisms of action (7781). Feather keratin hydrolysis by a Vibrio sp. Received 2018 Jan 3; Accepted 2018 May 31. Extracting and purification of the sample DNA is a critical step in the process, since the construction of a metagenomic library requires a sufficient amount of high-quality DNA. If expression host does not enable correct protein folding, additional procedures have to be introduced for proper formation of disulfide bridges (99). Comparison of different Bacillus subtilis expression systems.
Exposing B. subtilis to MNNG, for example, resulted in 2,5-fold higher keratinase activity in mutated strain than in the wild-type (109). Paul T, Das A, Mandal A, Jana A, Maity C, Adak A, et al. Hard keratins (found in hard excrescences, such as feathers, hair, nails and hooves) contain more disulphide bonds than soft, flexible keratins. (54), Thermoanaerobacter sp. The Sequencing of environmental metagenomes allows us to directly identify genes coding for enzymes with predicted activities via comparison to structurally similar sequences in the databases (75, 76). (139).
Leather industry is one of the oldest, fast-growing industries in the world and plays an important role in todays economy.
The sisters -helices of collagen, elastin and keratin recovered from animal by-products: Functionality, bioactivity and trends of application. New tools for discovering and characterizing microbial diversity. Federal government websites often end in .gov or .mil. AS-S10-II treatment with EMS resulted in mutants having a higher growth rate and keratinase production (101). Keratinase of an anaerobic thermophilic bacterium Thermoanaerobacter sp. This can either be done by traditional non-targeted approaches, such as physical (108) and chemical mutagenesis (109) or by the protein engineering approaches (110). Although the potential of keratinases for various biotechnological applications has long been recognized, the knowledge on these enzymes and their mechanisms of action on the substrate, production and optimization still needs to be expanded in order to make their industrial use feasible. Zymography is used as a semi-quantitative method for keratinase detection on solid phase, since it has several advantages over other methods (32). Sivasubramanian S, Murali Manohar B, Puvanakrishnan R. Mechanism of enzymatic dehairing of skins using a bacterial alkaline protease. O-phosphoserine content of intermediate filament subunits.
Behrens GA, Hummel A, Padhi SK, Schtzle S, Bornscheuer UT. JB 99. The applied substrates typically also act as enzyme inducers, however, it is essential that the screening medium be free of repressors and inhibitors of target enzymes such as pepstatin, high concentrations of dextrose or glucose (31). London, UK: IntechOpen Limited; 2013. https://doi.org/ 10.5772/55302 [. Purification and characterization of a novel exocellular keratinase from Kocuria rosea. Purification and properties of an extracellular cold-active protease from the psychrophilic bacterium Pseudoalteromonas sp. Anaerobic carboxydotrophic bacteria in geothermal springs identified using stable isotope probing. Among the latter, proteases are an extremely important group of enzymes due to their broad applicability scope (40, 118). proteolyticus, S. griseus, S. moderatus NRRL 3150, Streptomyces sp. Emerging new technologies that provide sufficient performance are necessary to support the testing of millions of samples in a highly reproducible manner. New directions and interactions in metagenomics research. Theoretical methane yield from proteins is 0.496 m3/kg of volatile solids (VS) (153, 154), but only around 0.21 m3/kg was reported to have been produced from waste feathers (155). There are also reports that representatives of some Gram-negative genera degrade this substrate: Vibrio sp. Enzymes suitable for use in detergents need to be compatible with other components of the washing agents, and exhibit activity and stability at higher pH values and temperatures. Bacterial keratinases: Useful enzymes for bioprocessing agroindustrial wastes and beyond. Most keratinases are considered inducible enzymes, but some are also expressed constitutively (41, 42).
Central helical domain of -keratins comprises approx. Development of high-throughput phenotyping of metagenomic clones from the human gut microbiome for modulation of eukaryotic cell growth.
Traditional processing of feathers includes high temperature and pressure, which are the cause of high costs and destruction of some essential amino acids (methionine, lysine and tryptophan). Zhang RX, Gong JS, Zhang DD, Su C, Hou YS, Li H, et al. Structures of protofibrils and microfibres are strengthened by disulphide bonds, hydrogen and hydrophobic interactions, which also play a crucial role in rigidity and recalcitrance of keratin molecules (16).
The positive effect is due to the fact that a strong inducible promotor controls the keratinase production in B. megaterium, resulting in a prompt and efficient turnout of enzymes without lag phase (158). (35), Nesterenkonia sp. 65% of the market (40).
One strategy with improved sensitivity involves the growth of cell library in microtiter plates, followed by chemical or physical lysis and activity detection (9092). Directed evolution is one of the most effective approaches to tailor biocatalysts for industrial purposes (106). Nam GW, Lee DW, Lee HS, Lee NJ, Kim BC, Choe EA, et al. Complete genome sequence of a keratin-degrading bacterium Chryseobacterium gallinarum strain DSM 27622T isolated from chicken. The disadvantages of this process include loss of natural wool character, yellowing of material, pollution of waste water with AOX (adsorbable organically bound halogens), affected biodegradability of fabric (caused by limited bioavailability) and high energy and time consumption (137). If agar plates are used, targeted activities can be linked to the survival of host organisms, which makes screening or selection sensitive and high-throughput. and Pseudomonas sp.
An alternative form of treatment is a topical application of antimycotic drugs directly to the affected area. This type of screening media used different substrates, including e.g. Sturmberger L, Wallace PW, Glieder A, Birner-Gruenberger R. Synergism of proteomics and mRNA sequencing for enzyme discovery.
Oftentimes, cloning of keratinase genes in a host that can easily be manipulated is essential for ensuring industrial enzyme yields needed for commercialization of the products. Feist AM, Herrgrd MJ, Thiele I, Reed JL, Palsson B. 1). aba W, Kope W, Chorazyk D, Kancelista A, Piegza M, Malik K. Biodegradation of pretreated pig bristles by Bacillus cereus B5esz. about navigating our updated article layout.
Bioimmobilization of keratinase using Bacillus subtilis and Escherichia coli systems. One of the unconventional applications is in pearl bleaching.
High-throughput screening for biocatalysts. The most convenient strategy for the detection of enzymes involves the use of chromogenic or fluorogenic substrates (107). Low yield is the result of low accessibility of nutrients due to compact keratin ultrastructure in feathers and can be increased by pretreatment (156). for the keratin degradation. Anaerobic degradation of feathers runs under thermophilic (151) or mesophilic (151, 152) conditions and usually includes different types of waste (manure, mixed bone fractions, leftovers and offal). Bouacem K, Bouanane-Darenfed A, Zara Jaouadi N, Joseph M, Hacene H, Ollivier B, et al.
Dettmer A, Cavalli , Ayub MAZ, Gutterres M. Optimization of the unhairing leather processing with enzymes and the evaluation of inter-fibrillary proteins removal: An environment-friendly alternative. Forgcs G, Lundin M, Taherzadeh MJ, Srvri Horvth I. Pretreatment of chicken feather waste for improved biogas production. During isolation, strains are usually first screened for their keratinolytic potential by qualitative or semi-quantitative methods (screening media), followed by more sophisticated molecular and biochemical methods of characterization (72). High density DNA then serves as a template to amplify the functional genes involved in the selected metabolic pathways by PCR, which allows the study of active microorganisms involved in the processes (95). (55) are also available. The intermediate filament architecture as determined by X-ray diffraction modeling of hard alpha-keratin. Moreover, functional metagenomics allows the detection of novel enzymes with no structural similarities to the already known enzymes. Serine peptidases: Classification, structure and function. These constantly contribute to the recycling of the carbon, nitrogen and sulphur by the degradation of vast amounts of keratinous waste (hair and birds feathers, etc.) Dayanandan A, Kanagaraj J, Sounderraj L, Govindaraju R, Suseela Rajkumar G. Application of an alkaline protease in leather processing: an ecofriendly approach. NJ276. Commonly known assays for protease activity detection apply agar/agarose plates, with incorporated target substrate (26).
Biochemical characterization of three keratinolytic enzymes from Stenotrophomonas maltophilia BBE11-1 for biodegrading keratin wastes. Demir T, Hame EE, ncel SS, Vardar-Sukan F. An optimization approach to scale up keratinase production by Streptomyces sp. Search for novel proteolytic enzymes aimed at textile and agro-industrial applications: An overview of current and novel approaches. Keratins typically consist of three domains with different secondary structures: head domain, central helical domain and tail domain (6). The aim of the following review is to approach comprehensively current knowledge on various aspects of these enzymes and their production that may be helpful for future research.
Nevertheless, it is important to note that constitutive expression of proteases is mostly associated with caseinolytic and not keratinolytic activity, and it is suggested that the keratinolytic enzymes are mainly inducible (8). Development of some recombinant keratinolytic strains with increased production of enzymes aims to increase and improve keratinous waste decomposition before/during anaerobic digestion (155). Reconstruction of biochemical networks in microorganisms. Despite many advantageous features of Bacillus sp., the use of this host may be limited due to reported plasmid instability (100). A perspective: Metatranscriptomics as a tool for the discovery of novel biocatalysts. The latter differ in their amino acid sequence and length (9).
Purification and characterization of a serine protease secreted by Brevibacillus sp.
nov., an extremely thermophilic bacterium isolated from a hot spring. Majority of currently described and applied keratinases originate from isolated microbial strains. Learn more Gegeckas A, Gudiukaite R, Debski J, Citavicius D. Keratinous waste decomposition and peptide production by keratinase from Geobacillus stearothermophilus AD-11. Environmentally safe alternatives to the chemicals used in this process are enzyme preparations, typically composed of proteases and lipases. Nevertheless, in addition to enzymatic treatment, further treatment of infected material with alkaline reagents, detergents and high temperatures is required. Currently, there are at least 30 different keratin polypeptides classified into various groups, depending on their unique physicochemical properties, molecular structure and the producing epithelial cells (6). Another type of target metagenomic enrichment method is stable-isotope probing (SIP) (94), in which microorganisms grow in the presence of isotopically labelled substrates.
In recent years different chemical, physical and enzymatic methods of pretreatment are being explored (155, 157). The binding of the repressor to the operator prevents transcription of the gene encoding for specific enzyme. Kalyuzhnaya MG, Lapidus A, Ivanova N, Copeland AC, McHardy AC, Szeto E, et al. Non-ionizing radiation (for example by UV light) results in the excitation of electrons in DNA molecules, which typically results in mutagenic effect. Differential extraction of keratin subunits and filaments from normal human epidermis. Keratinases are ubiquitous in nature and can be found in representatives from the three domains of life: Eukarya, Bacteria and Archaea.
The amino acid sequence and composition of keratins affect their folding, properties and functions of keratin filaments. According to regulation (EC) 1774/2002 (145) of the European parliament, keratinous waste is classified as the third category of animal products, meaning: (i) it is obtained from animal carcases, (ii) is not intended for human consumption, and (iii) should not transmit diseases to humans or animals (145). Novel binding sites for metal ions, active sites, etc. Due to their protective role, the structure of these proteins is very recalcitrant and resistant to the degradation by widespread enzymes (2).
The choice of a vector system depends on the quality of the extracted DNA and research goals, taking into account the size of inserted fragments, the required number of copies of the vector, type of the used host strain and potential methods of screening. The relatively rapid PCR-based method used in rational design involves splicing by overhang extension (SOE) (106) that generates improved protein variants containing modified (specific) amino acid. The epidermis plays a key role in fibre contraction during washing and dyeing processes. Hydrolysis of the amyloid prion protein and nonpathogenic meat and bone meal by anaerobic thermophilic prokaryotes and Streptomyces subspecies. Cysteine plays a key role in the formation of disulphide bonds, important for structural stability of these molecules (6). Several million tonnes of feathers per year represent one of the biggest waste byproducts of poultry industry, and an important source of environmental pollution (8, 149). Novel microbial-mediated modifications of wool. Zhang et al. Since conventional methods are based on aggressive and energetically demanding processes, enzymatic degradation of prions may be a promising approach for destruction of these highly aggregated proteins with structural similarities to keratin. Keratinases vis--vis conventional proteases and feather degradation. Jaouadi B, Ellouz-Chaabouni S, Ali MB, Messaoud EB, Naili B, Dhouib A, et al. Usually, peculiar microecosystems in which microorganisms have to adapt to the lack of nitrogen/carbon sources other than keratin represent the best sources of these enzymes (33, 68, 69). Currently, keratinase expression using heterologous systems would lay the foundation for its genetic manipulation, protein engineering and large scale enzyme preparation (98). (140, 141). Metagenomic approaches therefore sometimes involve custom-designed oligonucleotide hybridization probes, which hybridize to specific sequences in metagenomic libraries. The industry has a great interest in microorganisms that are capable of producing large amounts of efficient extracellular keratinases (33, 68, 69).
Tail domain or C-terminal part of protein contains globular structure.
Specific nucleases PstI and KpnI were used for improving stability of serine proteases from Bacillus sp., for which oxidation-sensitive methionine 222 was removed and replaced by non-oxidizing amino acid (Ser, Ala or Leu). An unbiased manner to mine natural microbial communities for new keratinases is by screening expression library for the desired enzymatic activity. The recombinant strain effectively degraded feathers prior to biogas production, which resulted in production of up to 80% of the theoretical methane yield originating from protein digestion. In vitro degradation of porcine skin epidermis by a fungal keratinase of Doratomyces microsporus. The role of proteases is to remove an outer layer of coarse fibre, reducing the rough feeling of the wool. Chemical agents, such as ethyl methylsulfonate (EMS), N-methyl-N-nitro-N-nitroso-guanidine (MNNG) or ethidium bromide, can also induce random mutations in DNA molecules. Molecular mass of bacterial keratinases ranges from 18 (enzyme SK1-02 from Streptomyces albidoflavus) to 200 kDa (enzymes from Kocuria rosea and Fervidobacterium islandicum), while the enzymes of pathogenic fungi can reach up to 440 kDa (for example keratinase II of Trichophyton mentagrophytes) (8, 24, 25). However, it is estimated that more than 99% of microorganisms from natural environments have not yet been isolated, which greatly reduces the number of available microbiological sources (73, 74).