Singh Anjali, Tyagi Madhu Bala, Kumar Ashok
School of Biotechnology, Institute of Science, Banaras Hindu University, Varanasi 221 005, India; Department of Botany, MMV, Banaras Hindu University, Varanasi 221005, India.
Department of Botany, MMV, Banaras Hindu University, Varanasi 221005, India.
Plant Physiol Biochem. 2017 Oct;119:110-120. doi: 10.1016/j.plaphy.2017.08.020. Epub 2017 Aug 31.
The present study describes cyanobacterial species composition and their dominance in biological crusts from barks of different trees, roof top of building and soil of agricultural field. An attempt was also made to explore the presence of photoprotective compounds such as mycosporine-like amino acids (MAAs) in the crust samples. Microscopic examination and growth studies revealed the presence of Oscillatoria species in all the crust samples excluding the crust of roof top of a building. Study on the abundance of dominant genera showed marked differences among various crust samples but Hapalosiphon, Lyngbya, Oscillatoria and Scytonema sp. were the most dominant genera, Oscillatoria being dominant in three crust samples. Screening for the presence of photoprotective compounds showed the presence of major peaks in the range of 308-334 nm thereby pointing to the presence of MAAs in all the crust samples. The highest amount of MAAs was found in the crust of Borassus flabellifer (15,729 nmol g dry wt of bark) followed by crust of roof top (14,543 nmol g dry wt of crust). MAAs were separated and partially purified employing HPLC, the most common MAA present in all the crusts was identified as mycosporine-glycine. Presence of mycosporine-glycine (M-Gly) was further confirmed by FTIR and NMR. Test of in vitro colonization on the bark of Mangifera indica and Azadirachta indica by three isolates namely Hapalosiphon, Oscillatoria and Scytonema sp. showed sign of active colonization. It is felt that identification of all the MAAs other than M-Gly may prove useful in future studies especially for assessing their significance in the protection mechanism of cyanobacteria/algae against various types of abiotic stresses.
本研究描述了不同树木树皮、建筑物屋顶和农田土壤生物结皮中的蓝藻物种组成及其优势度。还尝试探索结皮样品中光保护化合物如类菌胞素氨基酸（MAAs）的存在情况。显微镜检查和生长研究表明，除建筑物屋顶的结皮外，所有结皮样品中均存在颤藻属物种。对优势属丰度的研究表明，不同结皮样品之间存在显著差异，但单歧藻属、鞘丝藻属、颤藻属和伪枝藻属是最优势的属，颤藻属在三个结皮样品中占主导地位。光保护化合物存在情况的筛选显示，在308 - 334 nm范围内存在主要峰，从而表明所有结皮样品中均存在MAAs。在扇叶棕榈的结皮中发现的MAAs含量最高（树皮干重15,729 nmol/g），其次是屋顶结皮（结皮干重14,543 nmol/g）。采用高效液相色谱法对MAAs进行分离和部分纯化，确定所有结皮中最常见的MAA为菌胞素 - 甘氨酸。通过傅里叶变换红外光谱和核磁共振进一步证实了菌胞素 - 甘氨酸（M - Gly）的存在。单歧藻属、颤藻属和伪枝藻属的三个分离株在芒果和印楝树皮上的体外定殖试验显示出积极定殖的迹象。人们认为，鉴定除M - Gly以外的所有MAAs可能在未来研究中证明有用，特别是用于评估它们在蓝藻/藻类抵抗各种非生物胁迫的保护机制中的重要性。
