Kaliyamoorthy Kalidasan, Kandasamy Kathiresan, Chavanich Suchana, Kamlangdee Niyom, Vinithkumar Nambali Valsalan, Viyakarn Voranop
Center of Excellence for Marine Biotechnology, Department of Marine Science, Faculty of Science, Chulalongkorn University, Bangkok, Thailand.
Faculty of Marine Sciences, Annamalai University, Parangipettai, 608 502, India.
Sci Rep. 2025 Mar 7;15(1):8027. doi: 10.1038/s41598-025-87671-8.
This study investigated seasonal variations of thraustochytrids in rhizosphere soil collected from two mangrove species Rhizophora apiculata and Avicennia marina in natural and planted mangrove stands. Thraustochytrid counts were higher in the natural mangrove stand than in the planted site. The counts varied seasonally, being highest in the post-monsoon season followed by summer, monsoon, and pre-monsoon. Thraustochytrid counts exhibited positive correlations (p < 0.01) with counts of Total heterotrophic bacteria (THB), azotobacters, actinobacteria, fungi, yeasts, and Trichoderma. However, a negative correlation was observed with cyanobacteria. The counts also had positive correlation with silt, clay, nitrogen, phosphorus, potassium, chromium, copper, magnesium, cadmium, zinc and redox potential, but, negative correlations with temperature, pH, pore water salinity, total organic carbon and sand content of the soil samples. In the present study, 113 thraustochytrid strains were isolated from mangrove habitats. However, only 48 pure cultures survived after being sub-cultured three times. Based on survivability, color, and shape, two isolates from each sampling site in each season were selected. The predominant 24 isolates were identified based on their morphological, and molecular characteristics and were classified under five genera: Thraustochytrium, Schizochytrium, Botryochytrium, Parietichytrium, and Aurantiochytrium. Among the isolates, Aurantiochytrium sp. (AKTSK-06) produced the highest biomass of 15.71 g/L in the post-monsoon season (January-March, 2023), and Aurantiochytrium sp. (PVTSK-03) accumulated the highest lipid content of 61.33%. Thraustochytrids were found to contain Omega-3 poly unsaturated fatty acids (PUFAs), such as EPA up to 8.89% in Aurantiochytrium sp. (VRTSK-01), DPA up to 9.65% in Aurantiochytrium sp. (AKTSK-03), and DHA up to 47.46% in Aurantiochytrium sp. (AKTSK-06). Thus, mangroves provide an ideal ecological niche for thraustochytrids with an abundant supply of omega-3 fatty acids for potential industrial applications.
本研究调查了从天然和人工种植的红树林中两种红树植物——红树和白骨壤的根际土壤中破囊壶菌的季节变化。天然红树林中的破囊壶菌数量高于人工种植地。其数量随季节变化，在季风后季节最高，其次是夏季、季风季节和季风前季节。破囊壶菌数量与总异养细菌（THB）、固氮菌、放线菌、真菌、酵母和木霉的数量呈正相关（p < 0.01）。然而，与蓝细菌呈负相关。其数量还与淤泥、粘土、氮、磷、钾、铬、铜、镁、镉、锌和氧化还原电位呈正相关，但与温度、pH值、孔隙水盐度、土壤样品的总有机碳和砂含量呈负相关。在本研究中，从红树林栖息地分离出113株破囊壶菌菌株。然而，经过三次传代培养后，只有48个纯培养物存活下来。根据存活率、颜色和形状，从每个季节的每个采样点选择两株分离株。根据其形态和分子特征对24株优势分离株进行了鉴定，并分为五个属：破囊壶菌属、裂壶菌属、葡萄壶菌属、壁壶菌属和橙黄壶菌属。在这些分离株中，橙黄壶菌属（AKTSK - 06）在季风后季节（2023年1月至3月）产生的生物量最高，为15.71 g/L，橙黄壶菌属（PVTSK - 03）积累的脂质含量最高，为61.33%。发现破囊壶菌含有ω-3多不饱和脂肪酸（PUFA），如橙黄壶菌属（VRTSK - 01）中EPA含量高达8.89%，橙黄壶菌属（AKTSK - 03）中DPA含量高达9.65%，橙黄壶菌属（AKTSK - 06）中DHA含量高达47.46%。因此，红树林为破囊壶菌提供了理想的生态位，为潜在的工业应用提供了丰富的ω-3脂肪酸供应。
