Psychrophilic bacteria, living at low and mild temperatures, can contribute significantly to our understanding of microbial responses to temperature, markedly occurring in the bacterial membrane. Here, a newly isolated strain, Pseudomonas sp. B14-6, was found to dynamically change its unsaturated fatty acid and cyclic fatty acid content depending on temperature which was revealed by phospholipid fatty acid (PLFA) analysis. Genome sequencing yielded the sequences of the genes Δ-9-fatty acid desaturase (desA) and cyclopropane-fatty acid-acyl-phospholipid synthase (cfa). Overexpression of desA in Escherichia coli led to an increase in the levels of unsaturated fatty acids, resulting in decreased membrane hydrophobicity and increased fluidity. Cfa proteins from different species were all found to promote bacterial growth, despite their sequence diversity. In conclusion, PLFA analysis and genome sequencing unraveled the temperature-related behavior of Pseudomonas sp. B14-6 and the functions of two membrane-related enzymes. Our results shed new light on temperature-dependent microbial behaviors and might allow to predict the consequences of global warming on microbial communities.

生活在低温和温和温度下的嗜冷细菌可以极大地帮助我们理解微生物对温度的反应，这种温度在细菌膜中明显发生。在这里，一个新分离的菌株，假单胞菌sp。发现B14-6根据磷脂脂肪酸（PLFA）分析所揭示的温度动态地改变其不饱和脂肪酸和环状脂肪酸的含量。基因组测序产生了Δ-9-脂肪酸去饱和酶（desA）和环丙烷-脂肪酸-酰基-磷脂合成酶（cfa）的基因序列。desA在大肠杆菌中的过表达导致不饱和脂肪酸含量增加，导致膜疏水性降低和流动性提高。尽管它们的序列多样性，但都发现来自不同物种的Cfa蛋白都能促进细菌生长。总之，PLFA分析和基因组测序揭示了假单胞菌sp。的温度相关行为。B14-6和两种膜相关酶的功能。我们的结果为依赖温度的微生物行为提供了新的线索，并可能有助于预测全球变暖对微生物群落的影响。