Department of Morphology, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, B-9820, Merelbeke, Belgium.
Vet Microbiol. 2012 Aug 17;158(3-4):337-43. doi: 10.1016/j.vetmic.2012.02.025. Epub 2012 Feb 22.
Luminescent vibrios are amongst the most important pathogens in aquaculture, affecting almost all types of cultured organisms. Vibrio campbellii is one of these most important pathogens. In this study, the effects of feeding mnn9 yeast cell wall mutant and wild type yeast strain were investigated in the digestive tract of brine shrimp nauplii, Artemia franciscana, after experimental infection with V. campbellii (LMG 21363). Gnotobiotic A. franciscana nauplii were fed daily with dead Aeromonas hydrophila LVS3, and with either wild type strain of baker's yeast, Saccharomyces cerevisiae, or mutant strain mnn9, of which the cell wall contains elevated chitin and glucan and lower mannose levels. After three days of feeding, some nauplii were challenged with V. campbellii. Mean survival (%), individual length (mm) and total length (mm) at one day and two days after challenge were significantly higher in the group fed mnn9 than in the group fed wild type yeast (81 ± 1.50 and 63 ± 0.49, 1.56 ± 0.07 and 1.13 ± 0.02, 38.21 ± 3.11 and 21.26 ± 0.81 respectively for one day and 50 ± 2.37 and 20 ± 1.41, 2.33 ± 0.01 and 1.24 ± 0.04, 34.97 ± 5.56 and 7.45 ± 1.63 for two days after challenge). Histological examination revealed that the luminal diameter and enterocyte height of both mid- and hindgut were larger in the mnn9-fed group. Colonization of the gut lumen by V. campbellii could be observed by transmission electron microscopy for the group of nauplii fed with wild type yeast. Furthermore, it was observed that V. campbellii caused damage to the gut epithelium including shortening and disappearance of the microvilli, destruction of the apical cell membrane and cell lysis in the nauplii fed wild type yeast. The gut epithelium remained intact in challenged nauplii fed mnn9 yeast. The morphological findings of the present study further substantiate previous studies reporting a protective effect of this yeast cell wall mutant.
发光弧菌是水产养殖中最重要的病原体之一，几乎影响所有类型的养殖生物。坎贝尔弧菌是最重要的病原体之一。在本研究中，研究了在实验感染坎贝尔弧菌（LMG 21363）后，在丰年虾（Artemia franciscana）幼虫的消化道中，喂食 mnn9 酵母细胞壁突变体和野生型酵母菌株对幼虫的影响。无菌 A. franciscana 无节幼体每天喂食死的嗜水气单胞菌 LVS3，并喂食野生型酿酒酵母或突变体 mnn9，其细胞壁含有较高的几丁质和葡聚糖和较低的甘露糖水平。喂食三天后，一些无节幼体受到坎贝尔弧菌的挑战。在挑战后一天和两天时，喂食 mnn9 的组的存活率（%）、个体长度（mm）和总长度（mm）明显高于喂食野生型酵母的组（分别为 81 ± 1.50 和 63 ± 0.49、1.56 ± 0.07 和 1.13 ± 0.02、38.21 ± 3.11 和 21.26 ± 0.81），而在挑战后一天和两天时，喂食 mnn9 的组的存活率（%）、个体长度（mm）和总长度（mm）明显高于喂食野生型酵母的组（分别为 50 ± 2.37 和 20 ± 1.41、2.33 ± 0.01 和 1.24 ± 0.04、34.97 ± 5.56 和 7.45 ± 1.63）。组织学检查显示，在喂食 mnn9 的组中，中肠和后肠的腔直径和肠细胞高度均较大。通过透射电子显微镜观察到喂食野生型酵母的无节幼体的肠道腔中存在坎贝尔弧菌的定植。此外，还观察到在喂食野生型酵母的无节幼体中，坎贝尔弧菌导致肠上皮细胞损伤，包括微绒毛缩短和消失、顶膜破坏和细胞裂解。在喂食 mnn9 酵母的受挑战的无节幼体中，肠上皮保持完整。本研究的形态学发现进一步证实了先前研究报告的该酵母细胞壁突变体的保护作用。
