This study investigated the effect of growth conditions on proteolytic activity of six Pseudomonas strains, (Pseudomonas fragi DZ1, Pseudomonas koreensis DZ138, Pseudomonas rhodesiae DZ351, Pseudomonas fluorescens DZ390, Pseudomonas synxantha DZ832 and Pseudomonas lundensis DZ845), isolated from raw milk. The proteolytic activity of all Pseudomonas strains in dairy media (skim milk and whole milk) was significantly higher (p < 0.05) than in non-dairy media (TSB), with most activity from Pseudomonas grown in whole milk. The proteolytic activity from P. lundensis DZ845 grown in TSB with the addition of 5% (w/v) butter was higher than other dairy ingredients added to TSB and the amount of proteolytic activity increased with increasing concentrations of butter (from 5 to 15%). P. rhodesiae DZ351 showed little proteolytic activity in all TSB supplemented with dairy ingredients. Only four of the six strains produced one protease of 47 kDa when grown in TSB. However, all six strains were able to produce at least one type of proteases in milk medium. For P. lundensis DZ845, a 12% casein zymography gel revealed that the presence of butter could induce proteolytic activity. This is the first study showing the effect of milk fat (butter) on the proteolytic activity of Pseudomonas. This highlights the greater vulnerability of whole milk compared to skim milk to proteolytic activity.

中文翻译：

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乳脂会影响乳制品假单胞菌种类的蛋白水解酶活性。

本研究调查了生长条件对6株假单胞菌（pseudomonas fragi DZ1，koseensis Pseudomonas koreensis DZ138，Pseudomonas rhodesiae DZ351，Pseudomonas fluorescens DZ390，Pseudomonas synxantha DZ832和分离自普氏假单胞菌的牛奶）蛋白水解活性的影响。乳品培养基（脱脂奶和全脂牛奶）中所有假单胞菌菌株的蛋白水解活性均显着高于非乳品培养基（TSB）（p <0.05），其中大多数假单胞菌的蛋白水解活性均来自全脂奶。在TSB中添加5％（w / v）黄油而生长的P. lundensis DZ845的蛋白水解活性高于添加到TSB中的其他乳制品成分，并且蛋白水解活性的量随黄油浓度的增加而增加（从5％到15％ ）。P. 在所有添加了乳制品成分的TSB中，罗得西亚DZ351几乎没有蛋白水解活性。在TSB中生长时，六个菌株中只有四个菌株产生一种47 kDa的蛋白酶。但是，所有六种菌株都能够在牛奶培养基中产生至少一种蛋白酶。对于P. lundensis DZ845，一种12％的酪蛋白酶谱凝胶显示黄油的存在可以诱导蛋白水解活性。这是第一项显示乳脂（黄油）对假单胞菌蛋白水解活性影响的研究。与脱脂牛奶相比，这突出了全脂牛奶对蛋白水解活性的更大脆弱性。12％酪蛋白酶谱凝胶显示黄油的存在可以诱导蛋白水解活性。这是第一项显示乳脂（黄油）对假单胞菌蛋白水解活性影响的研究。与脱脂牛奶相比，这突出了全脂牛奶对蛋白水解活性的更大脆弱性。12％酪蛋白酶谱凝胶显示黄油的存在可以诱导蛋白水解活性。这是第一项显示乳脂（黄油）对假单胞菌蛋白水解活性影响的研究。与脱脂牛奶相比，这突出了全脂牛奶对蛋白水解活性的更大脆弱性。