Isembart Clémentine, Zimmermann Boris, Matić Josipa, Bolaño Losada Cristian, Afseth Nils K, Kohler Achim, Horn Svein J, Eijsink Vincent, Chylenski Piotr, Shapaval Volha
Faculty of Science and Technology, Norwegian University of Life Sciences, Drøbakveien 31, Ås, 1432, Norway.
Nofima AS, Ås, 1432, Norway.
Microb Cell Fact. 2025 May 21;24(1):118. doi: 10.1186/s12934-025-02743-8.
Feathers are a major by-product of the poultry industry, which poses an environmental challenge due to the recalcitrant structure of keratin, making them resistant to degradation. Traditional methods of feather handling, like conversion to feather meal, are energy-intensive and have limited efficiency. Biotechnological approaches, particularly microbial hydrolysis, offer a novel and more sustainable alternative for keratin degradation. This study evaluated feather hydrolysis by two bacterial strains, newly characterized cold-adapted Arthrobacter oryzae (BIM B-1663) and Bacillus licheniformis (CCM 2145), known as a keratin degrader, under various feather pre-treatment conditions, including washing, autoclaving, drying, and grinding.
Both bacterial strains were able to degrade pretreated feathers with a degradation efficiency of 75 to 90%, resulting in high ratios of nitrogen to carbon in the hydrolysates. B. licheniformis confirmed its enzymatic capabilities with high levels of general and specific protease activity and furthermore presented enriched amounts of amino acids of industrial interest. A. oryzae showed a much higher keratinase/protease activity ratio, demonstrating high specificity and efficiency of its enzymes. Autoclaving emerged as the most important determinant of microbial degradation efficiency and influenced the composition (peptide pattern, amino acid content, and chemical composition assessed through FTIR) of the resulting hydrolysates. Feather drying, although not improving microbial degradation efficiencies, had a considerable impact on hydrolysate composition.
The results show that both tested bacterial strains can efficiently degrade autoclaved feathers but use distinct enzymatic strategies to do so. Enriched profiles in amino acids and high nitrogen content in the hydrolysates also advocate for the benefits of microbial feather hydrolysis over an enzymatic one. To the authors' knowledge this study is the first to report a comprehensive evaluation of the impact of various feather pre-treatment methods on the efficiency of subsequent microbial feather hydrolysis and is the first one to report enrichment in phenylalanine, lysine, and tyrosine secreted by B. licheniformis.
羽毛是家禽业的主要副产品，由于角蛋白结构顽固，难以降解，给环境带来了挑战。传统的羽毛处理方法，如转化为羽毛粉，能源消耗大且效率有限。生物技术方法，特别是微生物水解，为角蛋白降解提供了一种新颖且更具可持续性的替代方案。本研究评估了两种细菌菌株对角蛋白的水解作用，这两种菌株分别是新鉴定的适冷米节杆菌（BIM B - 1663）和地衣芽孢杆菌（CCM 2145，一种已知的角蛋白降解菌），评估在包括洗涤、高压灭菌、干燥和研磨在内的各种羽毛预处理条件下它们的水解效果。
两种细菌菌株都能够降解预处理过的羽毛，降解效率为75%至90%，水解产物中氮碳比很高。地衣芽孢杆菌通过高水平的一般和特定蛋白酶活性证实了其酶促能力，此外还呈现出大量具有工业价值的氨基酸。米节杆菌显示出更高的角蛋白酶/蛋白酶活性比，证明其酶具有高特异性和效率。高压灭菌是微生物降解效率的最重要决定因素，并影响了所得水解产物的组成（通过傅里叶变换红外光谱评估的肽谱、氨基酸含量和化学成分）。羽毛干燥虽然没有提高微生物降解效率，但对水解产物组成有相当大的影响。
结果表明，两种受试细菌菌株都能有效降解经高压灭菌的羽毛，但采用了不同的酶促策略。水解产物中丰富的氨基酸谱和高氮含量也表明微生物羽毛水解比酶解更具优势。据作者所知，本研究首次全面评估了各种羽毛预处理方法对后续微生物羽毛水解效率的影响，也是首次报道地衣芽孢杆菌分泌的苯丙氨酸、赖氨酸和酪氨酸的富集情况。
