Food Safety and Intervention Technologies Research Unit, U.S. Department of Agriculture, Agricultural Research Service (ARS), Eastern Regional Research Center, Wyndmoor, Pennsylvania, USA.
Appl Environ Microbiol. 2013 Mar;79(6):1813-20. doi: 10.1128/AEM.02855-12. Epub 2013 Jan 11.
A study was conducted to determine the influence of arbuscular mycorrhizal (AM) fungi on Salmonella and enterohemorrhagic Escherichia coli O157:H7 (EHEC) in autoclaved soil and translocation into leek plants. Six-week-old leek plants (with [Myc+] or without [Myc-] AM fungi) were inoculated with composite suspensions of Salmonella or EHEC at ca. 8.2 log CFU/plant into soil. Soil, root, and shoot samples were analyzed for pathogens on days 1, 8, 15, and 22 postinoculation. Initial populations (day 1) were ca. 3.1 and 2.1 log CFU/root, ca. 2.0 and 1.5 log CFU/shoot, and ca. 5.5 and 5.1 CFU/g of soil for Salmonella and EHEC, respectively. Enrichments indicated that at days 8 and 22, only 31% of root samples were positive for EHEC, versus 73% positive for Salmonella. The mean Salmonella level in soil was 3.4 log CFU/g at day 22, while EHEC populations dropped to ≤ 0.75 log CFU/g by day 15. Overall, Salmonella survived in a greater number of shoot, root, and soil samples, compared with the survival of EHEC. EHEC was not present in Myc- shoots after day 8 (0/16 samples positive); however, EHEC persisted in higher numbers (P = 0.05) in Myc+ shoots (4/16 positive) at days 15 and 22. Salmonella, likewise, survived in statistically higher numbers of Myc+ shoot samples (8/8) at day 8, compared with survival in Myc- shoots (i.e., only 4/8). These results suggest that AM fungi may potentially enhance the survival of E. coli O157:H7 and Salmonella in the stems of growing leek plants.
一项研究旨在确定丛枝菌根（AM）真菌对灭菌土壤中沙门氏菌和肠出血性大肠杆菌 O157：H7（EHEC）的影响及其向韭菜植株的转移。将 6 周龄的韭菜植株（有[Myc+]或无[Myc-] AM 真菌）用约 8.2 log CFU/plant 的沙门氏菌或 EHEC 复合悬浮液接种到土壤中。在接种后第 1、8、15 和 22 天，对土壤、根和茎样本进行病原体分析。初始种群（第 1 天）分别为约 3.1 和 2.1 log CFU/根，约 2.0 和 1.5 log CFU/茎，约 5.5 和 5.1 CFU/g 土壤的沙门氏菌和 EHEC。富集分析表明，在第 8 天和第 22 天，只有 31%的 EHEC 根样本呈阳性，而沙门氏菌阳性率为 73%。第 22 天土壤中沙门氏菌的平均水平为 3.4 log CFU/g，而 EHEC 种群在第 15 天降至≤0.75 log CFU/g。总体而言，与 EHEC 相比，沙门氏菌在更多的茎、根和土壤样本中存活。在第 8 天之后，EHEC 未出现在 Myc-的茎中（16 个样本均为阴性）；然而，在第 15 天和第 22 天，Myc+的茎中 EHEC 的数量更高（P=0.05）（阳性样本为 4/16）。同样，在第 8 天，沙门氏菌在统计上存活于更多的 Myc+茎样本中（8/8），而在 Myc-茎中仅存活于 4/8 样本中。这些结果表明，AM 真菌可能会增强大肠杆菌 O157：H7 和沙门氏菌在生长韭菜植株茎中的存活。
