School of Biotechnology, KIIT University, Bhubaneswar 751024, India.
Gut Pathog. 2013 May 13;5(1):11. doi: 10.1186/1757-4749-5-11.
Salmonella enterica serovar Enteritidis infections are known to exhibit worldwide prevalence with increased morbidity and mortality. The conventional strategies like antibiotic therapy and vaccination have not only proved to be of sub-optimal efficacy but also led to the development of multidrug resistant strains of Salmonella. Antimicrobial activities of probiotics against various enteropathogens and other health promoting effects have assumed greater significance in recent years. The present study aims to evaluate the efficacy of a Lactobacillus plantarum strain (KSBT 56, isolated from a traditional food product of India), in preventing Salmonella enterica serovar Enteritidis growth and pathogenicity in vitro.
The cell free culture supernatant (CFCS) of KSBT 56 strain notably inhibited the growth of Salmonella Enteritidis without affecting the growth of other gram-positive lactic acid bacteria. The isolated KSBT 56 strain produces lactic acid similar to other standard probiotic strains like Lactobacillus plantarum MTCC 1407. The free radical production by KSBT 56 strain was studied by using sodC mutant of S. Enteritidis, which exhibited reduced growth in the presence of CFCS of the KSBT 56 strain, indicating the inhibitory activity of free radicals on the growth of S. Enteritidis. Our results also showed a significant reduction in the biofilm forming ability of Salmonella Enteritidis in the presence of the KSBT 56 strain (2 log cfu/ml, p = 0.01). Further, the anti-infective characteristics of KSBT 56 strain was validated by gentamicin protection assay which revealed 80% reduction in the invasion of Salmonella Enteritidis to HCT-116 cell line (Salmonella Enteritidis and KSBT 56 in a 1:1 ratio) and delayed addition of Salmonella Enteritidis by 1 h. Similarly, the reduced adhesion of Salmonella to the HCT-116 cells was observed along with the down regulation of hilA gene of Salmonella Pathogenicity Island 1 (SPI1) indicating that they might have acted synergistically to decrease the invasion of the pathogen into the cell line.
KSBT 56 strain effectively inhibited the growth, invasion and the biofilm forming ability of Salmonella Enteritidis without inhibiting the growth of other Lactobacillus strains. Overall, our result suggested that KSBT 56 can be used as a potential probiotic strain with considerable beneficial effects on the host.
肠沙门氏菌肠炎血清型感染在全球范围内普遍存在，发病率和死亡率均有所增加。抗生素治疗和疫苗接种等传统策略不仅疗效不佳，而且还导致了沙门氏菌多药耐药株的出现。近年来，益生菌对各种肠道病原体的抗菌活性和其他促进健康的作用显得更为重要。本研究旨在评估植物乳杆菌（KSBT56，从印度传统食品中分离得到）菌株对体外肠沙门氏菌肠炎血清型生长和致病性的抑制作用。
KSBT56 菌株的无细胞培养上清液（CFCS）显著抑制了沙门氏菌的生长，而不影响其他革兰氏阳性乳酸菌的生长。分离的 KSBT56 菌株产生的乳酸与其他标准益生菌菌株（如植物乳杆菌 MTCC1407）相似。使用沙门氏菌 sodC 突变株研究了 KSBT56 菌株的自由基产生情况，结果表明 KSBT56 菌株 CFCS 存在时，sodC 突变株的生长受到抑制，表明自由基对沙门氏菌生长的抑制作用。我们的结果还表明，KSBT56 菌株的存在显著降低了肠沙门氏菌的生物膜形成能力（2 对数 CFU/ml，p=0.01）。此外，通过庆大霉素保护试验验证了 KSBT56 菌株的抗感染特性，结果显示沙门氏菌对 HCT-116 细胞系的侵袭率降低了 80%（沙门氏菌与 KSBT56 以 1:1 的比例混合），并且沙门氏菌的添加时间延迟了 1 小时。同样，观察到沙门氏菌与 HCT-116 细胞的黏附减少，同时下调了沙门氏菌致病性岛 1（SPI1）的 hilA 基因，表明它们可能协同作用，减少病原体对细胞系的侵袭。
KSBT56 菌株能有效抑制肠沙门氏菌的生长、侵袭和生物膜形成能力，而不抑制其他乳杆菌的生长。总的来说，我们的结果表明，KSBT56 可以作为一种潜在的益生菌菌株，对宿主有相当大的有益影响。
