We collected >300 bacterial isolates from overwintering Dark-eyed Juncos (Junco hyemalis) to find that ∼40% appear to degrade the structural protein of feathers using extracellular keratinase enzymes. A guild of bacteria (∼18% of total counts) grew significantly better on basal salt medium (BSM) plates containing feather meal than on BSM agar-only plates (∼8% total counts). The genus-level profile of the 107 most active keratinolytic bacterial isolates shows that nearly half are Bacillus species. Keratinolytic Frigoribacterium, Microbacterium, Okibacterium, Pantoea, Sphingomonas, Staphylococcus, and Stenotrophomonas were found, among others. Active isolates were shown to degrade whole feathers, used feather meal as a sole carbon and energy source, and produced zones of clearing indicative of extracellular proteases on milk agar plates. Our novel in vitro keratinase assay uses ninhydrin to quantitate the release of amino acids from exogenously added keratin, with Bacillus licheniformis str. ATCC 14580 serving as a positive control. Keratinolytic isolates were grown in the presence of feather meal to induce keratinase release and this conditioned medium, called the enzyme extract, was clarified by centrifugation and filtration. The enzyme reaction was completed in 30 min and was positively correlated with the amount of extract added, until reaching color saturation. Bacillus pumilus str. F166 was the most active isolate and Bacillus cereus str. F65 was about half as active as the positive control. Bacillus cereus str. F27 performed well too. We also have demonstrated strong keratinolytic activity against raw wool α-keratin. Juncos are long-distance migrant birds that carry bacteria on their feathers, both beneficial and harmful to plants. The abundant keratinolytic bacteria on feathers are capable of structurally damaging the feathers, potentially reducing bird fitness and reproductive success. Keratinases have uses in tanning, silage, and remediation. Keratinases may be useful in the treatment of onychomycoses and actinic keratoses in medical and veterinary settings.

我们从越冬的黑眼琼科斯 ( Junco hyemalis ) 中收集了 300 多个细菌分离物，发现约 40% 的细菌似乎使用细胞外角蛋白酶降解羽毛的结构蛋白。一个细菌公会（占总数的 18%）在含有羽毛粉的基础盐培养基（BSM）板上的生长明显好于在仅 BSM 琼脂的板上（总计数的 8%）。107 种最活跃的角质溶解细菌分离物的属水平概况显示，近一半是芽孢杆菌属物种。角质溶解冷杆菌属、微杆菌属、奥克氏杆菌属、泛菌属、鞘氨醇单胞菌属、葡萄球菌属和窄食单胞菌属被发现，等等。活性分离物被证明可以降解整根羽毛，使用羽毛粉作为唯一的碳和能源，并在牛奶琼脂板上产生指示细胞外蛋白酶的透明区域。我们的新型体外角蛋白酶测定使用茚三酮来定量从外源添加的角蛋白中释放的氨基酸，使用地衣芽孢杆菌str。ATCC 14580 作为阳性对照。角质分解分离物在羽毛粉存在下生长以诱导角蛋白酶释放，并且这种称为酶提取物的条件培养基通过离心和过滤进行澄清。酶反应在 30 分钟内完成，并与添加的提取物量呈正相关，直至达到颜色饱和。短小芽孢杆菌海峡 F166 是最活跃的分离株和蜡状芽孢杆菌str。F65 的活性约为阳性对照的一半。蜡状芽孢杆菌str。F27也表现不错。我们还展示了对原毛 α-角蛋白的强角蛋白溶解活性。Juncos是长距离迁徙鸟类，它们的羽毛上携带细菌，对植物有益也有害。羽毛上丰富的角质分解细菌能够在结构上破坏羽毛，可能会降低鸟类的适应性和繁殖成功率。角蛋白酶可用于鞣制、青贮和修复。角蛋白酶可用于治疗医学和兽医环境中的甲癣和光化性角化病。