Oscillatoria kawamurae is an unusual freshwater cyanobacterium because of its large trichome and ambiguous gas vacuole. Because little is known about its phenotypic or genotypic characteristics, this study conducted morphological, biochemical, and genetic characterization of O. kawamurae strains isolated from Japan, Laos, and Myanmar. All strains displayed similar morphological characteristics; however some differences were observed in vegetative cell widths, trichome colors, and the distribution patterns of their gas vacuole‐like structures. The in vivo and phycobiliprotein absorption spectra revealed the two different trichome colors found in the four representative strains of O. kawamurae (Inle1, Lao7, Biwa6, and Inba3). These different trichome colors corresponded to the different ratios of phycoerythrin and phycocyanin, the two types of phycobilin pigments: 0.25 for olive‐green strain (Inle1) and 0.65–0.73 for brown‐green strains (Biwa6, Inba3, and Lao7). Cellular fatty acid compositions of the four strains were C14:0, C15:0, C16:0, C16:1c, C17:0, C18:0, C18:1c, C18:3α and C18:4, whereas two strains (Biwa6 and Inba3) lacked C17:0. Of the fatty acids, palmitic acid (C16:0) was predominant. PCR experiments using primers targeting a gas vesicle gene (gvpA) recovered gvpA fragments from all O. kawamurae strains, suggesting that this species has true gas vacuoles. The 16S rDNA sequences of all of the strains were identical regardless of their different trichome colors and/or geographic origins. Phylogenetic analyses based on the 16S rDNA sequences indicated that O. kawamurae forms a monophyletic clade with O. princeps CCALA 1115 clB1 and O. duplisecta ETS‐06. We discuss the taxonomy of O. kawamurae based on the data obtained in this study.

中文翻译：

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从不同地理区域分离的 Oscillatoria kawamurae (Oscillatoriales, Cyanobacteria) 的形态、生化和分子特征

Oscillatoria kawamurae 是一种不寻常的淡水蓝藻，因为它的毛状体大，气泡不明确。由于对其表型或基因型特征知之甚少，本研究对从日本、老挝和缅甸分离的 O. kawamurae 菌株进行了形态学、生化和遗传表征。所有菌株都表现出相似的形态特征；然而，在营养细胞宽度、毛状体颜色和它们的气泡状结构的分布模式方面观察到了一些差异。体内和藻胆蛋白吸收光谱揭示了在 O. kawamurae 的四个代表性菌株（Inle1、Lao7、Biwa6 和 Inba3）中发现的两种不同毛状体颜色。这些不同的毛状体颜色对应于藻红蛋白和藻蓝蛋白的不同比例，两种藻胆素色素：橄榄绿色菌株（Inle1）为0.25，棕绿色菌株（Biwa6、Inba3和Lao7）为0.65-0.73。四种菌株的细胞脂肪酸组成为 C14:0、C15:0、C16:0、C16:1c、C17:0、C18:0、C18:1c、C18:3α 和 C18:4，而两种菌株（Biwa6和 Inba3) 缺少 C17:0。在脂肪酸中，棕榈酸（C16:0）占优势。使用靶向气泡基因 (gvpA) 的引物进行的 PCR 实验从所有 O. kawamurae 菌株中回收了 gvpA 片段，表明该物种具有真正的气泡。所有菌株的 16S rDNA 序列都是相同的，无论它们的毛状体颜色和/或地理起源如何。基于 16S rDNA 序列的系统发育分析表明 O. kawamurae 与 O.princeps CCALA 1115 clB1 和 O. duplisecta ETS-06 形成单系进化枝。