Bovine lactoferrin (bLF) is an iron-binding glycoprotein used in functional and therapeutic products due to its biological properties, the most important being its antimicrobial activity. In this study, hydrolysates of bovine lactoferrin (bLFH) obtained with pepsin, chymosin and microbial rennet were assayed against Cronobacter sakazakii (104 CFU/mL) in different media: phosphate buffered saline (PBS), bovine skim milk and whey, and reconstituted powdered infant formula (PIFM). The results obtained have shown that hydrolysis of bLF enhances its antibacterial activity against C. sakazakii. The three types of bLFH dissolved in PBS reduced C. sakazakii growth from a concentration of 0.1 mg/mL and inhibited it completely above 0.5 mg/mL, after 4 and 8 h of incubation at 37 °C. The three bLFH (1 and 2 mg/mL) did not show any antibacterial activity in skim milk, whey and reconstituted PIFM after 8 h of incubation at 37 °C. However, C. sakazakii growth was completely inhibited in whey when pepsin and chymosin bLFH (2 mg/mL) were combined with undigested bLF (2 mg/mL), after 8 h of incubation at 37 °C. On the other hand, the combination of any of the three hydrolysates with bLF showed very low activity in skim milk and practically no activity in reconstituted PIFM. Furthermore, the effect of temperature after reconstitution (4, 23 and 37 °C), on the antibacterial activity of bLF (2.5 and 5 mg/mL) in reconstituted PIFM contaminated with C. sakazakii (10-102 CFU/mL) was also investigated. bLF at 5 mg/mL significantly reduced (p < .05) the proliferation of C. sakazakii in reconstituted PIFM at 37 °C until 2 h. C. sakazakii did not grow at 4 °C for 6 days in reconstituted PIFM with or without bLF. The effect of microwave heating (450, 550 and 650 W for 5, 10 and 15 s) on the antibacterial activity and stability of bLF (2.5 mg/mL) in reconstituted PIFM contaminated with C. sakazakii (10-102 CFU/mL) was also studied. The antibacterial activity of bLF was maintained after treatments at 450 and 550 W for 5 s, which kept 94 and 89% of bLF immunoreactivity, respectively. Moreover, microwave treatments of reconstituted PIFM with or without bLF, at 650 W for 5 s, and at 450, 550 and 650 W for 10 and 15 s, completely inactivated C. sakazakii.

中文翻译：

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水解和微波处理对天然牛​​乳乳铁蛋白对阪崎肠杆菌的抗菌活性的影响。

牛乳铁蛋白（bLF）由于其生物学特性，是一种用于功能和治疗产品的铁结合糖蛋白，最重要的是其抗菌活性。在这项研究中，用胃蛋白酶，凝乳酶和微生物凝乳酶获得的牛乳铁蛋白（bLFH）的水解产物在不同介质中测定了阪崎肠杆菌（104 CFU / mL）：磷酸盐缓冲液（PBS），牛脱脂牛奶和乳清，然后重新配制为粉末状婴儿配方奶粉（PIFM）。获得的结果表明，bLF的水解增强了其对阪崎肠杆菌的抗菌活性。在37°C孵育4和8小时后，溶于PBS的三种bLFH浓度从0.1 mg / mL降低了阪崎肠杆菌的生长，并在0.5 mg / mL以上完全抑制了阪崎肠杆菌的生长。在37°C孵育8小时后，三种bLFH（1和2 mg / mL）在脱脂牛奶，乳清和复溶PIFM中均未显示任何抗菌活性。但是，在37°C孵育8小时后，如果将胃蛋白酶和凝乳酶bLFH（2 mg / mL）与未消化的bLF（2 mg / mL）混合，则阪崎肠杆菌的生长就完全被乳清抑制了。另一方面，三种水解产物中任何一种与bLF的结合在脱脂牛奶中的活性都非常低，而在重组PIFM中则几乎没有活性。此外，重构后温度（4、23和37°C）对被阪崎肠杆菌（10-102 CFU / mL）污染的重组PIFM中bLF（2.5和5 mg / mL）的抗菌活性也有影响。调查。5 mg / mL的bLF在37°C的PIFM中直至2 h显着降低（p <.05）阪崎肠杆菌的增殖。C。含或不含bLF的重组PIFM中，sakazakii在4°C下连续6天没有生长。微波加热（450、550和650 W，持续5、10和15 s）对经阪崎肠杆菌（10-102 CFU / mL）污染的重组PIFM中bLF（2.5 mg / mL）的抗菌活性和稳定性的影响也进行了研究。在450 W和550 W下处理5 s后，bLF的抗菌活性得以保持，分别保持94％和89％的bLF免疫反应性。此外，在有或没有bLF的情况下，重组PIFM的微波处理在650 W下持续5 s，在450、550和650 W下分别进行10和15 s，完全灭活了阪崎肠杆菌。还研究了被阪崎肠杆菌污染的重构PIFM（10-102 CFU / mL）中的5 mg / mL）。在450 W和550 W下处理5 s后，bLF的抗菌活性得以保持，分别保持94％和89％的bLF免疫反应性。此外，用或不用bLF对重组PIFM进行微波处理，在650 W下持续5 s，在450、550和650 W下分别进行10和15 s，可以完全灭活阪崎肠杆菌。还研究了被阪崎肠杆菌污染的重构PIFM（10-102 CFU / mL）中的5 mg / mL）。在450 W和550 W下处理5 s后，bLF的抗菌活性得以保持，分别保持94％和89％的bLF免疫反应性。此外，用或不用bLF对重组PIFM进行微波处理，在650 W下持续5 s，在450、550和650 W下分别进行10和15 s，可以完全灭活阪崎肠杆菌。