腊肉拮抗菌分离及抗真菌脂肽特性分析

从传统腊肉中筛选拮抗菌株,纯化鉴定新型抗菌物质并对其抗菌特性研究,为抗菌脂肽在食品防腐中的应用提供理论依据.采用抑菌圈法筛选拮抗菌株;通过酸沉淀、硅胶柱层析和半制备反相高效液相色谱分离纯化抗菌脂肽;通过傅里叶红外光谱、基质辅助激光解吸电离飞行时间质谱对脂肽鉴定.结果 表明,筛选得到12株拮抗细菌,其中菌株XLP27对革...

Isolation of Antagonistic Bacteria from Smoked Bacon and Analysis of Antifungal Properties of Its Lipopeptides

This study aimed to isolate and identify antagonistic bacteria from traditional smoked bacon, to determine the bacteriostatic activity of one selected isolate, and to purify and identify lipopeptide from its fermentation broth for the purpose of providing a theoretical basis for the application of the antimicrobial lipopeptide in food preservation. The inhibition zone method was adopted for screening the antagonistic strains. The antimicrobial lipopeptide was isolated and purified using a simple three-step procedure involving acid precipitation, silica gel column chromatography and reversed-phase high performance liquid chromatography (RP-HPLC), and it was identified by Fourier transform infrared spectroscopy (FT-IR) and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS). A total of 12 bacterial isolates were obtained, including XLP27, which had obvious antifungal and antibacterial effects on both Gram-positive and Gram-negative strains as well as one yeast strain and four mould strains. The antagonistic strain XLP27 was identified as Bacillus pumilu. The antibacterial substances produced by strain XLP27 were synthesized mainly in the stationary growth phase and the maximum yield was reached after 60 h of culture. One antimicrobial compound was purified from the fermentation broth and identified as lipopeptide iturin A, which had five isoforms with protonated masses of m/z 1 046.182, 1 060.213, 1 074.198, 1 088.201 and 1 102.175, representing fatty acid chain length of C14–C18. The lipopeptide was extremely heat stable (30 min at 40–100 ℃), remained active over a wide pH range (4–10) and was found to be resistant to all proteolytic enzymes tested. Iturin A had broad-spectrum antibacterial activity and good stability, and thus could have the potential to be an alternative to traditional antibacterial agents in the fields of food preservation and agricultural biological control.