摘要

Neptunomonas sp。 BPy-1是从红藻藻Pyropia yezoensis的体外培养物中分离的附生细菌。它使用乙醇作为唯一碳源并促进寄主藻类的生长。相关的细菌Neptunomonas sp。 BZm-1是从Yatsushiro Sea（日本）中发现的Zostera码头的叶子中分离出来的。 BZm-1与Neptunomonas sp。具有99％的16S rRNA序列同一性。 BPY-1。与BPy-1类似，BZm-1在含有乙醇或丁醇的人造海水（ASW）培养基中生长。当用多酶清洁剂处理菌体时，处理后菌体的生长受到阻碍，但向培养基中添加BZm-1促进了生长。为了探索附生细菌的益处，在有限的营养物质条件下检查了分离的细菌产生的吲哚乙酸（IAA）。 Salkowski分析和GC-MS分析显示BZm-1和BPy-1在含有葡萄糖或乙醇的ASW培养基中在色氨酸存在下生长期间分泌IAA。在含有色氨酸但缺乏碳源的ASW培养基中，分离株不生长，但生成IAA。 ASW培养基包括硝酸盐作为唯一的氮源。在不存在碳源的情况下，在色氨酸存在下不同的氮形式不影响两种分离物的IAA产生。这些发现表明，两种分离物产生的IAA严格依赖于色氨酸，但受碳和氮源的影响较小。根据BPy-1和BZm-1的不同来源，这种IAA生产模式似乎在BPy-1亲属中保守。

Neptunomonas sp. BPy-1 is an epiphytic bacterium isolated from in vitro culture of the red algaPyropia yezoensis. It uses ethanol as a sole carbon source and promotes the growth of host alga. A related bacterium, Neptunomonas sp. BZm-1, was isolated from leaves of Zostera marina found in the Yatsushiro Sea (Japan). BZm-1 showed 99% 16S rRNA sequence identity with Neptunomonas sp. BPy-1. Similar to BPy-1, BZm-1 grew in artificial seawater (ASW) medium containing ethanol or butanol. When thalli were treated with a multi-enzyme cleaner, the growth of treated thalli was retarded, but the addition of BZm-1 to the medium promoted growth. To explore the benefits of epiphytic bacteria, indoleacetic acid (IAA) production by isolated bacteria was examined under conditions of limited nutrients. Salkowski assays and GC-MS analysis revealed that both BZm-1 and BPy-1 excreted IAA during growth in ASW medium containing glucose or ethanol in the presence of tryptophan. In ASW medium containing tryptophan but lacking a carbon source, neither isolate grow, but produced IAA. ASW medium includes nitrate as the sole nitrogen source. In the absence of carbon source, different nitrogen forms in the presence of tryptophan did not affect IAA production by the two isolates. These findings indicate that IAA production by the two isolates is strictly dependent on tryptophan but less affected by carbon and nitrogen sources. Based on the different origins of BPy-1 and BZm-1, this mode of IAA production seems to be conserved among relatives of BPy-1.

https://link.springer.com/article/10.1007/s00203-017-1439-1