Morphometric Characterization and Biochemical Comparison of Eight Diatom Strains Isolated From Coastal Areas of Baja California Sur, México

Abstract

Diatoms are a group of unicellular microalgae with a very attractive biochemical composition for biotechnology and aquaculture. This study aimed to characterize the morphometry and compare the biochemistry of eight diatom strains—Amphora sp., Entomoneis sp., Nanofrustulum shiloi, Navicula salinicola, Navicula sp., Nitzschia inconspicua, Psammodictyon panduriforme, and Odontella aurita—isolated from coastal areas of Baja California Sur, México. Morphometric analyses revealed cell volumes ranging from 16.2 to 794.0 µm3 and specific growth rates between 0.3 and 0.4 days−1. Ash content ranged from 13.6% to 25.9% dry weight. Biochemical composition varied among strains, with protein (27.1–42.0%), carbohydrates (5.8–26.4%), and lipids (19.4–42.3%). Pigments included chlorophyll a (1.6–5.3%), chlorophyll c (0.4–1.0%), and total carotenoids (1.3–3.5%). Fatty acids were dominated by C14:0, C16:0, C16:1n7, and eicosapentaenoic acid (EPA; 20:5n-3), with arachidonic acid (ARA; 20:4n6) present in most strains except Entomoneis sp. These isolates’ morphometric and biochemical traits were comparable to those of diatom species widely used in aquaculture, suggesting their potential as alternative live feeds. Although direct feeding or toxicity assays were not performed, these comparative analyses provide a robust basis for proposing potential applications in aquaculture and biotechnology.