Pseudomonas fluorescens ATCC13525 is an important growth-promoting rhizobacteria (PGPR) and plant disease biocontrol bacterium. However, due to poor stress resistance, it is prone to be inactivated by preparation, drying and storage. In this study, we investigated the effects of different stress preadaptation methods (2.0∼3.0 wt% NaCl, 0.01∼0.20 wt% H₂O₂, and 35∼44 °C) and two stress adaptation genes (rpoS, and hfq) on the stress resistance of P. fluorescens ATCC13525 (PF-WT). After stress preadaptation with low stress of 3.0 wt% NaCl, 0.05 wt% H₂O₂, and 41 °C for 30 min, the tolerance of PF-WT toward high lethal stress environments (20.0 wt% NaCl, 1.00 wt% H₂O₂, and 47 °C) were significantly improved. Moreover, knockout of rpoS and hfq genes resulted in slower culture growth than PF-WT under the sublethal stress culture conditions (5.0 wt% NaCl, 0.08 wt% H₂O₂, and 35 °C), whereas rpoS and hfq overexpressed strains (PF-pBBR2-rpoS and PF-pBBR2-hfq) obviously grew better than the control strain PF-pBBR2. Further, we prepared biocontrol agents (BACs) of different strains after different stress preadaptation treatments. Compared to PF-WT without stress preadaptation, preadaptation by 0.05 wt% H₂O₂ for 30 min resulted in 5.65 times higher survival rate, while treatment with 3.0 wt% NaCl for 30 min of PF-pBBR2-rpoS led to 5.60 times higher survival rate. This finding provides the simple and effective protection methods for P. fluorescens ATCC13525 BACs preparation by stress preadaptation and overexpression of stress adaptation genes.

荧光假单胞菌ATCC13525 是一种重要的促进生长的根际细菌 (PGPR) 和植物病害生防细菌。但由于抗逆性差，在制备、干燥和贮藏过程中容易失活。在本研究中，我们研究了不同的胁迫预适应方法（2.0∼3.0 wt % NaCl、0.01∼0.20 wt % H ₂ O ₂和 35∼44 °C）和两种胁迫适应基因（rpoS和hfq）对的耐应力性荧光假单胞菌ATCC13525（PF-WT）。用 3.0 wt % NaCl、0.05 wt % H ₂ O _{2 的}低应力进行应力预适应后和 41 °C 30 min，PF-WT 对高致死应力环境（20.0 wt % NaCl、1.00 wt % H ₂ O ₂和 47 °C）的耐受性显着提高。此外，在亚致死应激培养条件（5.0 wt % NaCl、0.08 wt % H ₂ O ₂和35°C）下，rpoS和hfq基因的敲除导致比 PF-WT 更慢的培养生长，而rpoS和hfq过表达菌株（ PF-pBBR2- rpoS和 PF-pBBR2- hfq) 明显优于对照菌株 PF-pBBR2。此外，我们在不同的胁迫预适应处理后制备了不同菌株的生物防治剂（BAC）。与没有应激预适应的 PF-WT 相比，通过 0.05 wt % H ₂ O ₂预适应30 分钟导致存活率提高 5.65 倍，而用 3.0 wt % NaCl 处理 30 分钟的 PF-pBBR2- rpoS导致存活率提高 5.60 倍存活率。这一发现为通过胁迫预适应和胁迫适应基因的过表达制备荧光假单胞菌ATCC13525 BACs提供了简单有效的保护方法。