Camacho Antonio, Rochera Carlos, Picazo Antonio
Cavanilles Institute of Biodiversity and Evolutionary Biology, University of Valencia, Valencia, Spain.
Front Microbiol. 2022 Sep 23;13:900158. doi: 10.3389/fmicb.2022.900158. eCollection 2022.
The role of competitive interactions based on resource utilisation was explored in a phototrophic microbial mat from Byers Peninsula (Maritime Antarctica). Shotgun metagenomic profiling of the mat showed a taxonomic and functionally diverse microbial community. The heterotrophic bacterial community was dominated by Proteobacteria, where genera typically found in polar habitats, such as , , and , were highly prevalent. Cyanobacteria played the main role as primary producers, accompanied by diatoms and chlorophytes. To test the potential effects of the inorganic nutrient (N and P) availability on this community, a fully factorial nitrate and phosphorus addition experiment was conducted . The mat exhibited a functional and structural response to the nutrient amendments. Compared to the undisturbed mat, phosphorus fertilisation favoured the growth of (non-heterocystous) cyanobacteria relative to that of diatoms, as indicated by changes in the carotenoid pigment biomarkers. Although no mat accretion was visible, fertilisation improved the phototrophic activity, and, mainly, when P was amended, the production of exopolymeric substances was favoured, whereas further changes in the vertical distribution of primary production activity were observed as well. Illumina amplicon sequencing of the 16S rRNA gene also demonstrated changes in the relative abundance of heterotrophic prokaryotes, which were detectable from the phylum to the genus level and mainly related to the amendment of nitrogen. Predictions made on the functional skills of these shifted prokaryotic communities indicated changes in abundance selecting taxa with a metabolic adaptation to the new nutrient scenarios. They mainly consisted of the enhancement of ecological strategies and metabolic regulatory mechanisms related to the uptake and metabolising of either nitrogen or phosphorus, regulated by its availability whether in a balanced way or not. This study is a pioneer in demonstrating how shifts in the regional dynamic of nutrients might alter the metabolic equilibrium of these initially considered homeostatic benthic communities. They can be accordingly considered as taxonomically diverse microbiomes with a functional repertoire still inclined to respond to the biogeochemical alteration of nutrient cycles, although occurring in a cold extreme environment where biological activity is partially restricted by environmental harshness.
基于资源利用的竞争相互作用在拜尔斯半岛（南极海洋）的光合微生物垫中的作用得到了研究。对该微生物垫进行的鸟枪法宏基因组分析显示出一个分类和功能多样的微生物群落。异养细菌群落以变形菌门为主，通常在极地栖息地发现的属，如 、 和 ，非常普遍。蓝细菌作为主要生产者发挥主要作用，硅藻和绿藻相伴。为了测试无机养分（氮和磷）可用性对该群落的潜在影响，进行了一项完全析因的硝酸盐和磷添加实验。该微生物垫对养分添加表现出功能和结构上的响应。与未受干扰的微生物垫相比，施肥相对于硅藻更有利于（非异形胞）蓝细菌的生长，类胡萝卜素色素生物标志物的变化表明了这一点。尽管没有可见的微生物垫堆积，但施肥提高了光合活性，而且，主要是在添加磷时，有利于胞外聚合物的产生，同时也观察到初级生产活动垂直分布的进一步变化。对16S rRNA基因进行的Illumina扩增子测序也证明了异养原核生物相对丰度的变化，这些变化在门到属的水平上都可检测到，并且主要与氮的添加有关。对这些发生变化的原核生物群落功能技能的预测表明，丰度的变化选择了对新养分环境具有代谢适应性的分类群。它们主要包括与氮或磷的吸收和代谢相关的生态策略和代谢调节机制的增强，这些机制由其可用性以平衡或不平衡的方式调节。这项研究率先证明了区域养分动态变化如何改变这些最初被认为是稳态底栖群落的代谢平衡。因此，它们可被视为分类多样的微生物群落，其功能库仍倾向于对养分循环的生物地球化学变化做出响应，尽管发生在生物活性部分受到环境严酷性限制的寒冷极端环境中。
