Department of Biology, Lakehead University, 955 Oliver Road, Thunder Bay, ON P7B 5E1, Canada.
Can J Microbiol. 2009 Oct;55(10):1176-86. doi: 10.1139/w09-081.
The survival of and interactions between a Pseudomonas putida strain labelled with a red fluorescent protein gene (WT-rfp) and its green fluorescent protein gene-labelled rpoS(-) mutant (KO-gfp) were examined. The generation times of the planktonic WT-rfp and KO-gfp in trypticase soy broth were not significantly different (i.e., p > 0.05) from each other at 30 degrees C. However, the biovolume of the KO-gfp biofilm was about 7 times larger than its WT-rfp counterpart after 48 h of growth. Furthermore, the presence of WT-rfp suppressed the biofilm development of KO-gfp significantly in co-culture biofilms. In planktonic conditions, the pre-carbon-starved WT-rfp achieved a 3-fold greater survival than the pre-carbon-starved KO-gfp in 0.85% saline after a 13-day incubation. In a 1:1 ratio co-culture, the pre-carbon-starved WT-rfp outcompeted the pre-carbon-starved KO-gfp by 20-fold. However, the survival of WT-rfp and KO-gfp were not significantly different from each other in biofilm conditions. Additionally, 11.4% and 61.2% of the WT-rfp and KO-gfp biofilms, respectively, remained intact after washing in 0.2% SDS for 60 min. In conclusion, the rpoS had a significant impact on survival and competitiveness of planktonic P. putida, and on biofilm development, being implicated in competitive suppression of biofilm development in co-culture biofilms and decreased biofilm cohesiveness.
一株带有红色荧光蛋白基因（WT-rfp）的恶臭假单胞菌菌株及其绿色荧光蛋白基因标记的 rpoS(-) 突变株（KO-gfp）的存活和相互作用进行了研究。在 30°C 时，浮游 WT-rfp 和 KO-gfp 在胰蛋白酶大豆肉汤中的世代时间没有显著差异（即，p > 0.05）。然而，KO-gfp 生物膜的生物体积在 48 小时的生长后比其 WT-rfp 对应物大约大 7 倍。此外，在共培养生物膜中，WT-rfp 的存在显著抑制了 KO-gfp 的生物膜发育。在浮游条件下，经过 13 天的孵育，预碳饥饿的 WT-rfp 在 0.85%盐水中的存活比预碳饥饿的 KO-gfp 高 3 倍。在 1:1 的共培养中，预碳饥饿的 WT-rfp 比预碳饥饿的 KO-gfp 竞争优势高 20 倍。然而，在生物膜条件下，WT-rfp 和 KO-gfp 的存活没有显著差异。此外，WT-rfp 和 KO-gfp 生物膜分别有 11.4%和 61.2%在 0.2% SDS 中洗涤 60 分钟后仍保持完整。总之，rpoS 对浮游恶臭假单胞菌的存活和竞争力以及生物膜发育有显著影响，涉及到对共培养生物膜中生物膜发育的竞争抑制和降低生物膜内聚性。
