Department of Biological Sciences, University of Southern California, Los Angeles, CA, 90089, USA.
Department of Marine Science, University of Otago, Dunedin, 9016, New Zealand.
Environ Microbiol Rep. 2021 Jun;13(3):401-406. doi: 10.1111/1758-2229.12948. Epub 2021 Apr 18.
Microbial rhodopsins are simple light-harvesting complexes that, unlike chlorophyll photosystems, have no iron requirements for their synthesis and phototrophic functions. Here, we report the environmental concentrations of rhodopsin along the Subtropical Frontal Zone off New Zealand, where Subtropical waters encounter the iron-limited Subantarctic High Nutrient Low Chlorophyll (HNLC) region. Rhodopsin concentrations were highest in HNLC waters where chlorophyll-a concentrations were lowest. Furthermore, while the ratio of rhodopsin to chlorophyll-a photosystems was on average 20 along the transect, this ratio increased to over 60 in HNLC waters. We further show that microbial rhodopsins are abundant in both picoplankton (0.2-3 μm) and in the larger (>3 μm) size fractions of the microbial community containing eukaryotic plankton and/or particle-attached prokaryotes. These findings suggest that rhodopsin phototrophy could be critical for microbial plankton to adapt to resource-limiting environments where photosynthesis and possibly cellular respiration are impaired.
微生物视紫红质是简单的光捕获复合物，与叶绿素光合系统不同，其合成和光养功能不需要铁。在这里，我们报告了新西兰近海亚热带锋区的视紫红质环境浓度，在这里，亚热带水域遇到铁限制的亚热带高营养低叶绿素 (HNLC) 区域。视紫红质浓度在叶绿素 -a 浓度最低的 HNLC 水域中最高。此外，虽然沿剖面的视紫红质与叶绿素 -a 光合系统的比率平均为 20，但在 HNLC 水域中，该比率增加到 60 以上。我们进一步表明，微生物视紫红质在微微型浮游生物（0.2-3 μm）和微生物群落的较大（>3 μm）尺寸部分中都很丰富，其中包含真核浮游生物和/或附着在颗粒上的原核生物。这些发现表明，视紫红质光合作用对于微生物浮游生物适应资源限制环境可能至关重要，在这些环境中光合作用和可能的细胞呼吸受到损害。
