Instituto de Recursos Naturales y Agrobiología de Sevilla (IRNAS-CSIC), Apartado 1052, Seville 41080, Spain.
Aberdeen Oomycete Laboratory, University of Aberdeen, Institute of Medical Sciences , Foresterhill, Aberdeen AB25 2ZD, United Kingdom.
Environ Sci Technol. 2016 Jul 19;50(14):7633-40. doi: 10.1021/acs.est.6b00994. Epub 2016 Jun 23.
The controlled mobilization of pollutant-degrading bacteria has been identified as a promising strategy for improving bioremediation performance. We tested the hypothesis whether the mobilization of bacterial degraders may be achieved by the action of eukaryotic zoospores. We evaluated zoospores that are produced by the soil oomycete Pythium aphanidermatum as a biological vector, and, respectively, the polycyclic aromatic hydrocarbon (PAH)-degrading bacteria Mycobacterium gilvum VM552 and Pseudomonas putida G7, acting as representative nonflagellated and flagellated species. The mobilization assay was performed with a chemical-in-capillary method, in which zoospores mobilized bacterial cells only when they were exposed to a zoospore homing inducer (5% (v/v) ethanol), which caused the tactic response and settlement of zoospores. The mobilization was strongly linked to a lack of bacterial motility, because the nonflagellated cells from strain M. gilvum VM552 and slightly motile, stationary-phase cells from P. putida G7 were mobilized effectively, but the actively motile, exponentially grown cells of P. putida G7 were not mobilized. The computer-assisted analysis of cell motility in mixed suspensions showed that the swimming rate was enhanced by zoospores in stationary, but not in exponentially grown, cells of P. putida G7. It is hypothesized that the directional swimming of zoospores caused bacterial mobilization through the thrust force of their flagellar propulsion. Our results suggest that, by mobilizing pollutant-degrading bacteria, zoospores can act as ecological amplifiers for fungal and oomycete mycelial networks in soils, extending their potential in bioremediation scenarios.
已确定控制降解菌的迁移是提高生物修复性能的一种有前途的策略。我们检验了这样一个假设，即真核游动孢子的作用是否可以实现细菌降解者的迁移。我们评估了土壤卵菌腐霉属产生的游动孢子作为生物载体，以及多环芳烃（PAH）降解细菌分枝杆菌 VM552 和假单胞菌 G7 分别作为代表性的无鞭毛和有鞭毛的物种。迁移测定是用毛细管内化学法进行的，其中只有当游动孢子暴露于游动孢子归巢诱导剂（5%（v/v）乙醇）时，游动孢子才能迁移细菌细胞，这会导致游动孢子的趋性反应和定殖。这种迁移与细菌缺乏运动性密切相关，因为来自菌株 M. gilvum VM552 的无鞭毛细胞和运动性较弱的静止期细胞 P. putida G7 可有效迁移，但活跃运动的指数生长期细胞 P. putida G7 则不能迁移。在混合悬浮液中对细胞运动性的计算机辅助分析表明，游动孢子增强了静止期但不能增强指数生长期 P. putida G7 细胞的游动速度。我们假设，游动孢子的定向游动通过其鞭毛推进产生的推力导致细菌迁移。我们的研究结果表明，游动孢子通过迁移降解菌，可以作为土壤中真菌和卵菌菌丝网络的生态放大器，从而在生物修复场景中扩展其潜力。
