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. 2023 Feb 10;10(2):138.
doi: 10.3390/vetsci10020138.

Iron Bioaccessibility and Speciation in Microalgae Used as a Dog Nutrition Supplement

Thomas Dalmonte  1 , Carla Giuditta Vecchiato  1 , Giacomo Biagi  1 , Micaela Fabbri  1 , Giulia Andreani  1 , Gloria Isani  1
Affiliations

Iron Bioaccessibility and Speciation in Microalgae Used as a Dog Nutrition Supplement

Thomas Dalmonte et al. Vet Sci. .

Abstract

Chlorella vulgaris, Arthrospira platensis, Haematoccocus pluvialis, and Phaeodactylum tricornutum are species of interest for commercial purposes due to their valuable nutritional profile. The aim of this study was to investigate the iron content in these four microalgae, with emphasis on their iron bioaccessibility assessed using an in vitro digestion system to simulate the process which takes place in the stomach and small intestine of dogs, followed by iron quantification using atomic absorption spectrometry. Furthermore, the extraction of soluble proteins was carried out and size exclusion chromatography was applied to investigate iron speciation. Significant differences (p < 0.004) in iron content were found between C. vulgaris, which had the highest (1347 ± 93 μg g-1), and H. pluvialis, which had the lowest (216 ± 59 μg g-1) iron content. C. vulgaris, A. platensis, and H. pluvialis showed an iron bioaccessibility of 30, 31, and 30%, respectively, while P. tricornutum showed the lowest bioaccessibility (11%). The four species analysed presented soluble iron mainly bound to proteins with high molecular mass ranging from >75 to 40 kDa. C. vulgaris showed the highest iron content associated with good bioaccessibility; therefore, it could be considered to be an interesting natural source of organic iron in dog nutrition.

Keywords: Arthrospira platensis; Chlorella vulgaris; Haematococcus pluvialis; Phaedactylum tricornutum; biochemical characterisation; in vitro digestion.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Iron content in the four microalgae (A. platensis, C. vulgaris, H. pluvialis, P. tricornutum) analysed. The data are expressed as micrograms per gram of dry algae biomass and are reported as medians and interquartile ranges. * Significantly different for the Dunn post-hoc test (p < 0.05).
Figure 2
Figure 2
Iron distribution between the supernatants (soluble fractions) and pellets (insoluble fractions) obtained after the extraction of A. platensis, C. vulgaris, H. pluvialis, and P. tricornutum. The data are expressed as percentages.
Figure 3
Figure 3
Chromatographic profiles of total proteins after SEC of extracts from algal samples. Proteins were detected at 280 nm. Each chromatographic profile is the mean of two chromatographies. AP = A. platensis; PT = P. tricornutum; HP = H. pluvialis; CV = C. vulgaris.
Figure 4
Figure 4
Chromatographic profiles of iron after SEC of extracts from algal samples. Iron concentration is expressed as µg mL−1. Each chromatographic profile is the mean of two chromatographies. AP = A. platensis; PT = P. tricornutum; HP = H. pluvialis; CV = C. vulgaris.
Figure 5
Figure 5
A chromatographic profile of phycocyanin after SEC of the A. platensis extract. Phycocyanin concentration is reported as mg mL−1. The chromatographic profile is the mean of two chromatographies.
Figure 6
Figure 6
Chromatographic profiles of chlorophyll a after SEC of extracts from algal biomass. Chlorophyll a was detected at 430 nm. Each chromatographic profile is the mean of two chromatographies.
Figure 7
Figure 7
A chromatographic profile of astaxanthin after SEC of an H. pluvialis extract. Astaxanthin was detected at 477 nm. The chromatographic profile is the mean of two chromatographies.
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