Keskes Sahar, Ben Khedher Saoussen, Masmoudi Fatma, Saadaoui Imen, Tounsi Slim
Biopesticides Laboratory, Center of Biotechnology of Sfax, Sfax University, P.O. Box 1177, 3018, Sfax, Tunisia.
High Agronomic Institute of Chott Mariem, Sousse University, 4042, Sousse, Tunisia.
Int Microbiol. 2025 Jul 7. doi: 10.1007/s10123-025-00692-1.
Bacillus cabrialesii HB7, a novel halotolerant strain isolated from Qatari soil, can effectively promote tomato plant growth and mitigate saline stress and has a great biofertilizer potential. Due to its promising agronomical and biotechnological potential, high spore densities should be achieved, to extend its use. In this study, culture conditions were optimized with different methods to improve HB7 spore production. Firstly, three culture media were tested to find the best medium for high spore density. When using the semisynthetic medium supplemented with 15 g.L NaCl, high spore production was achieved compared to complex medium and G10 media with and without NaCl addition. Secondly, key fermentation parameters were determined by Plackett-Burman design, and the optimum levels of six components (yeast extract, KHPO, casein hydrolysate, (NH)SO, NaCl concentrations, and pH) were optimized with a hybrid design, achieving 1.82 × 10 spore.mL and a threefold spore production improvement, when compared to the basal medium. Moreover, HB7 exhibited faster cell growth (0.97 h vs. 0.53 h) and glucose uptake (1.09 h vs. 0.89 h) after optimization. These findings may play a pivotal role in the synthesis of an effective biofertilizer based on B. cabrialesii HB7 for sustainable agriculture and biotechnological advancements.
卡氏芽孢杆菌HB7是从卡塔尔土壤中分离出的一种新型耐盐菌株，能有效促进番茄植株生长并缓解盐胁迫，具有巨大的生物肥料潜力。由于其在农学和生物技术方面具有广阔前景，为扩大其应用范围，应实现高孢子密度。在本研究中，采用不同方法优化培养条件以提高HB7的孢子产量。首先，测试了三种培养基以找出最适合高孢子密度的培养基。当使用添加15 g.L NaCl的半合成培养基时，与添加和不添加NaCl的复合培养基及G10培养基相比，孢子产量较高。其次，通过Plackett-Burman设计确定关键发酵参数，并采用混合设计优化六种成分（酵母提取物、KHPO、酪蛋白水解物、(NH)SO、NaCl浓度和pH）的最佳水平，与基础培养基相比，孢子产量达到1.82×10孢子.mL，提高了三倍。此外，优化后HB7的细胞生长速度更快（0.97小时对0.53小时），葡萄糖摄取速度也更快（1.09小时对0.89小时）。这些发现可能在基于卡氏芽孢杆菌HB7合成有效生物肥料以促进可持续农业和生物技术进步方面发挥关键作用。
