Faculty of Science, Alexandria University, Moharrem Bey, Alexandria, 21511, Egypt.
National Institute of Oceanography and Fisheries (NIOF), Alexandria, Egypt.
BMC Microbiol. 2024 Aug 6;24(1):293. doi: 10.1186/s12866-024-03426-x.
There is an enormous diversity of life forms present in the extremely intricate marine environment. The growth and development of seaweeds in this particular environment are controlled by the bacteria that settle on their surfaces and generate a diverse range of inorganic and organic chemicals. The purpose of this work was to identify epiphytic and endophytic bacterial populations associated with ten common marine macroalgae from various areas along the Mediterranean Sea coast in Alexandria. This was done to target their distribution and possible functional aspects. Examine the effects of the algal habitat on the counting and phenotypic characterization of bacteria, which involves grouping bacteria based on characteristics such as shape, colour, mucoid nature, type of Gram stain, and their ability to generate spores. Furthermore, studying the physiological traits of the isolates under exploration provides insight into the optimum environmental circumstances for bacteria associated with the formation of algae. The majority of the bacterial isolates exhibited a wide range of enzyme activities, with cellulase, alginase, and caseinase being the most prevalent, according to the data. Nevertheless, 26% of the isolates displayed amylolytic activity, while certain isolates from Miami, Eastern Harbor, and Montaza lacked catalase activity. Geographical variations with the addition of algal extract may impact on the enumeration of the bacterial population, and this might have a relationship with host phylogeny. The most significant observation was that endophytic bacteria associated with green algae increased in all sites, while those associated with red algae increased in Abu Qir and Miami sites and decreased in Eastern Harbor. At the species level, the addition of algal extract led to a ninefold increase in the estimated number of epiphytic bacteria for Cladophora pellucida in Montaza. Notably, after adding algal extract, the number of presented endophytic bacteria associated with Codium sp. increased in Abu Qir while decreasing with the same species in Montaza. In addition to having the most different varieties of algae, Abu Qir has the most different bacterial isolates.
海洋环境极其复杂，存在着大量的生命形式。在这种特殊的环境中，海藻的生长和发育受到定居在其表面的细菌的控制，这些细菌会产生各种无机和有机化学物质。本研究的目的是确定与来自亚历山大地中海沿岸不同地区的十种常见海洋大型藻类相关的附生和内生细菌种群。这是为了确定它们的分布和可能的功能方面。研究藻类栖息地对细菌计数和表型特征的影响，包括根据形状、颜色、黏液性质、革兰氏染色类型以及产生孢子的能力等特征对细菌进行分组。此外，研究所研究的分离物的生理特征可以深入了解与藻类形成相关的细菌的最佳环境条件。根据数据，大多数细菌分离物表现出广泛的酶活性，其中纤维素酶、褐藻酸酶和酪蛋白酶最为常见。然而，26%的分离物显示出淀粉酶活性，而来自迈阿密、东港和蒙塔扎的某些分离物缺乏过氧化氢酶活性。添加藻类提取物的地理变化可能会影响细菌种群的计数，这可能与宿主系统发育有关。最显著的观察结果是，与绿藻相关的内生细菌在所有地点都增加了，而与红藻相关的内生细菌在阿布奎尔和迈阿密地点增加，在东港地点减少。在种水平上，在蒙塔扎的 Cladophora pellucida 中，添加藻类提取物使估计的附生细菌数量增加了九倍。值得注意的是，添加藻类提取物后，与 Codium sp. 相关的内生细菌数量在阿布奎尔增加，而在蒙塔扎则减少。除了拥有最多样化的藻类外，阿布奎尔还有最多样化的细菌分离物。
