Santra Hiran Kanti, Banerjee Debdulal
Microbiology and Microbial Biotechnology Laboratory, Department of Botany and Forestry, Vidyasagar University, Midnapore, India.
Front Fungal Biol. 2022 Jan 4;2:796010. doi: 10.3389/ffunb.2021.796010. eCollection 2021.
Endophytic entities are ubiquitous in nature with all-square bioactivity ranging from therapeutic effects toward animals to growth promoting attributes and stress tolerance activities in case of green plants. In the present study, the club moss for the first time has been subjected for the isolation of endophytic fungi. An exopolysaccharide (EPS) extracted from LCS1, an endophytic fungi isolated from Linn., was characterized as a β-glucan heteropolymer (composed of mannose, rhamnose, arabinose, glucose, galactose, and fucose) which plays a pivotal role in obliterating the drought stress in rice seedlings () when applied at an amount of 20, 50, and 100 ppm. The fresh weight contents of rice tissue (39%), total chlorophyll (33%), proline (41%), soluble sugar content (26%) along with antioxidant enzymes such as catalase, peroxidase, and super-oxide dismutase increased (in comparison to control of non-EPS treated seedlings) while malondialdehyde content had reduced markedly after 30 days of regular treatment. The drought resistance of rice seedling was observed at peak when applied at 50 ppm dosage. Vital parameters for EPS production like fermentation duration (5 days), medium pH (6), nutrient (carbon (glucose-7 g%/l), nitrogen (yeast extract-0.4 g%/l), and mineral (NaCl-0.10 g%/l) sources, oxygen requirements (O vector or liquid alkane-n-hexane, n-heptane, n-hexadecane), and headspace volume (250 ml Erlenmeyer flask- 50 ml medium, 200 ml-headspace volume) were optimized to obtain an enhanced EPS yield of 17.38 g/L-59% higher than the preoptimized one. The present study, for the first time, reported the β-glucan rich heteropolysaccharide from Colletotrichum origin which is unique in structure and potent in its function of drought stress tolerance and could enhance the sustainable yield of rice cultivation in areas facing severe drought stress.
内生生物在自然界中普遍存在，具有广泛的生物活性，从对动物的治疗作用到促进绿色植物生长的特性以及抗逆活性。在本研究中，首次对石松进行了内生真菌的分离。从石松中分离出的内生真菌LCS1所提取的一种胞外多糖（EPS）被表征为一种β-葡聚糖杂聚物（由甘露糖、鼠李糖、阿拉伯糖、葡萄糖、半乳糖和岩藻糖组成），当以20、50和100 ppm的量施用时，它在消除水稻幼苗的干旱胁迫方面起着关键作用。常规处理30天后，水稻组织的鲜重含量（39%）、总叶绿素（33%）、脯氨酸（41%）、可溶性糖含量（26%）以及过氧化氢酶、过氧化物酶和超氧化物歧化酶等抗氧化酶均有所增加（与未用EPS处理的幼苗对照相比），而丙二醛含量显著降低。当以50 ppm的剂量施用时，观察到水稻幼苗的抗旱性达到峰值。对EPS生产的关键参数进行了优化，如发酵时间（5天）、培养基pH值（6）、营养物质（碳源（葡萄糖-7 g%/l）、氮源（酵母提取物-0.4 g%/l）和矿物质（氯化钠-0.10 g%/l）来源）、氧气需求（O向量或液态烷烃-正己烷、正庚烷、正十六烷）以及顶空体积（250 ml锥形瓶-50 ml培养基，200 ml顶空体积），以获得比预优化产量提高59%的17.38 g/L的EPS产量。本研究首次报道了源自炭疽菌属的富含β-葡聚糖的杂多糖，其结构独特，在耐旱胁迫功能方面具有强大作用，并且可以提高面临严重干旱胁迫地区水稻种植的可持续产量。
