Agroscope Liebefeld-Posieux Research Station ALP, 3003 Bern, Switzerland.
Int J Food Microbiol. 2011 May 14;147(1):26-32. doi: 10.1016/j.ijfoodmicro.2011.02.032. Epub 2011 Mar 1.
In vitro and in situ anti-listerial properties of 3 strains of Facultative Anaerobic Halophilic and Alkaliphilic (FAHA) species, i.e. Alkalibacterium kapii ALK 6, Marinilactibacillus psychrotolerans ALK 9 and Facklamia tabacinasalis ALK 1, were investigated. The 3 strains were isolated from a smear ecosystem originating from a commercial Raclette type cheese and exhibiting strong anti-listerial activity in situ on cheese surface. In a first step, strains were tested in vitro for production of antimicrobial compounds against Listeria innocua 81000-1 and Listeria ivanovii HPB 28. M. psychrotolerans ALK 9 inhibited both indicator strains in spot-on-the-lawn tests while A. kapii ALK 6 showed no inhibiting effect. F. tabacinasalis ALK 1 exerted an in vitro inhibition on L. ivanovii HPB 28, but induced the formation of dense ball-shaped microcolonies of L. innocua 81000-1 in the soft agar, a typical biofilm microstructure. The extent of the biofilm zone was enhanced when F. tabacinasalis ALK 1 and M. psychrotolerans ALK 9 were tested together. In a second step, different combinations of strains were applied on Raclette cheeses ripened at pilot scale and contaminated with 50 cfu/cm(2)L. innocua at day 7. A control flora of 6 strains, isolated from ecosystem F and corresponding to species commonly found on smear cheeses, was applied on control and test cheeses. In test cheeses, we investigated the impact on Listeria growth of the addition of the 3 FAHA strains, applied as single or mixed cultures. A 1-log inhibition was obtained at day 15 on cheeses treated with FAHA strains applied either as single or mixed cultures. This 1-log inhibition was correlated with the development of FAHA species that reached their maximal count at day 15. This study suggests that the development of FAHA species in early ripening likely contributes to the initial part of the in situ inhibition exerted by the complex cheese surface ecosystem investigated.
我们研究了 3 株兼性厌氧嗜盐嗜碱（FAHA）种，即 Alkalibacterium kapii ALK 6、Marinilactibacillus psychrotolerans ALK 9 和 Facklamia tabacinasalis ALK 1 的体外和原位抗李斯特菌特性。这 3 株菌是从商业 Raclette 型奶酪的涂片生态系统中分离出来的，该生态系统在奶酪表面具有很强的原位抗李斯特菌活性。在第一步中，我们测试了菌株在体外对指示菌 Listeria innocua 81000-1 和 Listeria ivanovii HPB 28 产生抗菌化合物的能力。Marinilactibacillus psychrotolerans ALK 9 在点-草皮测试中抑制了两种指示菌，而 Alkalibacterium kapii ALK 6 没有抑制作用。Facklamia tabacinasalis ALK 1 在体外对 Listeria ivanovii HPB 28 有抑制作用，但在软琼脂中诱导 Listeria innocua 81000-1 形成密集的球形微菌落，这是典型的生物膜微观结构。当 Facklamia tabacinasalis ALK 1 和 Marinilactibacillus psychrotolerans ALK 9 一起测试时，生物膜区的范围增大。在第二步中，我们将不同的菌株组合应用于在中试规模上成熟并在第 7 天用 50 cfu/cm(2)L. innocua 污染的 Raclette 奶酪。我们将从生态系统 F 中分离出的 6 株与在涂片奶酪上常见的种相对应的控制菌群应用于对照和试验奶酪。在试验奶酪中，我们研究了添加 3 株 FAHA 菌株作为单一或混合培养物对李斯特菌生长的影响。在第 15 天，用 FAHA 菌株作为单一或混合培养物处理的奶酪中，李斯特菌的生长被抑制了 1 个对数级。这种 1 个对数级的抑制与 FAHA 种的发展有关，这些种在第 15 天达到了最大数量。这项研究表明，FAHA 种在早期成熟过程中的发展可能有助于研究的复杂奶酪表面生态系统在原位抑制李斯特菌的初始部分。
