# Halamphora kolbei (Aleem) Álvarez-Blanco et S. Blanco 2014, A Rare Diatom from the Black Sea: Morphological Observations and Revised Description with Biochemical Composition

## TL;DR

This study provides a detailed description of the rare diatom Halamphora kolbei and shows it can produce valuable omega-3 fatty acids.

## Contribution

The paper offers a revised taxonomy and highlights the biotechnological potential of Halamphora kolbei for omega-3 production.

## Key findings

- Halamphora kolbei is a promising source of eicosapentaenoic acid.
- The study reveals high levels of C14–C16 fatty acids in the species.
- Detailed morphological and phylogenetic data are provided for accurate identification.

## Abstract

This study addresses the isolation and taxonomic characterisation of the poorly known diatom Halamphora kolbei, integrating fundamental and applied research perspectives. Due to its small cell size and incomplete original description, H. kolbei has remained difficult to identify, and published data on the species are extremely scarce. In this work, we summarise the available literature and provide a detailed morphological description of a strain isolated from Sevastopol Bay (Black Sea) using light microscopy, scanning electron microscopy, and phylogenetic analysis. In addition, the strain was evaluated for its productivity and biochemical composition. The results demonstrate that H. kolbei is a promising source of eicosapentaenoic acid, an essential omega-3 polyunsaturated fatty acid. This study contributes to the taxonomy and phylogeny of the genus Halamphora and highlights the biotechnological potential of this species for the sustainable production of high-value nutrients.

The species Halamphora kolbei is a rarely reported diatom, and information on its distribution and characteristics is limited. The original taxonomic description of this species is inaccurate and insufficient for identification, as the available literature contains scarce and scattered data. In the present study, we summarised the available data on this species and provided a detailed description of the strain isolated from Sevastopol Bay of the Black Sea. Findings from a phylogenetic analysis of two genes, 18S rRNA and rbcL, are presented. The process of isolation, identification and establishment of a monoculture of the H. kolbei is described in detail. In addition, the productivity and biochemical characteristics were evaluated to assess the biotechnological potential of the strain. The growth rate, biomass productivity and protein, carbohydrate, lipid and fatty acid composition of this species were determined in this study, under controlled conditions. The high content of C14–C16 acids in H. kolbei has been revealed to make it a promising source of eicosapentaenoic acid. The detailed description of the species, its photographs and phylogeny, as well as additional morphological keys presented in the paper, will enable scientists around the world to study this species as a promising biological resource.