Proximate composition of marine invertebrates from tropical coastal waters, with emphasis on the relationship between nitrogen and protein contents

Abstract

ABSTRACT. The chemical profiles of Desmapsamma anchorata, Hymeniacidon heliophila (Porifera), Bunodosoma caissarum, Renilla muelleri (Cnidaria), Aplysia brasiliana, Eledone massyae, Isognomon bicolor (Mollusca), Echinaster brasiliensis, Echinometra lucunter, Holothuria grisea, Lytechinus variegatus (Echinodermata), and Phallusia nigra (Chordata) were determined. Hydrosoluble protein was the most abundant class of substances for all species, except for the ascidian Phallusia nigra, in which the carbohydrate content was higher. The percentages of hydrosoluble protein (dry weight, dw) varied widely among the invertebrates, ranging from 5.88% (R. muelleri) to 47.6% (Eledone massyae) of the dw .The carbohydrate content fluctuated from 1.3% (R. muelleri) to 18.4% (Aplysia brasiliana) of the dw. For most of the species, lipid was the second most abundant class of substances, varying from 2.8% (R. muelleri) to 25.3% (Echinaster brasiliensis) of the dw. Wide variations were also found for the invertebrates nitrogen content, with the lowest value recorded in the cnidarian R. muelleri (2.02% of the dw) and the highest in the molluscan E. massyae (12.7% of the dw). The phosphorus content of the dw varyed from 0.24% (R. muelleri) to 1.16% (E. massyae). The amino acid composition varied largely among the species, but for most of the species glycine, arginine, glutamic acid, and aspartic acid were the most abundant amino acids, with histidine and tyrosine among the less abundant amino acids. The actual content of total protein in the samples was calculated by the sum of amino acid residues, establishing dw values that fluctuated from 11.1% (R. muelleri) to 66.7% (E. massyae). The proteinaceous nitrogen content was high in all species, with an average value of 97.3% of the total nitrogen. From data of total amino acid residues and total nitrogen, specific nitrogen-to-protein conversion factors were calculated for each species. The nitrogen-to-protein conversion factors ranged from 5.10 to 6.15, with an overall average of 5.45. The use of the specific nitrogen-to-protein conversion factors established here is recommended, since it would yield more accurate determinations of total protein in the species tested in this study. Keywords: nitrogen-to-protein conversion factors, total protein, amino acid composition, lipid, carbohydrate, tropical Atlantic. Composición proximal de invertebrados marinos de aguas costeras tropicales,con énfasis en la relación entre los contenidos de nitrógeno y proteína RESUMEN. Se determinaron los perfiles químicos de Desmapsamma anchorata, Hymeniacidon heliophila (Porifera), Bunodosoma caissarum, Renilla muelleri (Cnidaria), Aplysia brasiliana, Eledone massyae, Isognomon bicolor (Mollusca), Echinaster brasiliensis, Echinometra lucunter, Holothuria grisea, Lytechinus variegatus (Echinodermata), y Phallusia nigra (Chordata). La clase más abundante de sustancias para todas las especies fueron las proteínas hidrosolubles, excepto para la ascidia Phallusia nigra, en la que el contenido de carbohidratos fue ...

Calculation of Nitrogen‐to‐Protein Conversion Factors: A Review with a Focus on Soy Protein

“…Values of k A and k P for fish range from 5.51 to 6.21 and 4.75 to 5.71, respectively (Table ). Salo‐Väänänen and Koivistoinen (), Diniz et al (), and Diniz et al () argued that the summing of amino acid weights would be the best method of calculating total protein in fish and marine samples, but until that is standardized, they propose that k P values are most practical and take into account varying amounts of NPN.…”

Comparing the capacity of five different dietary treatments to optimise growth and nutritional composition in two scleractinian corals

“…N is a constituent of essential structural and functional macromolecules (i.e. amino acids (AA), peptides, proteins, and photosynthetic pigments) [14]. In particular, N in the form of protein plays vital roles in most biological processes, such as enzymatic catalysis, transport and storage, immunity, and growth [14].…”

“…amino acids (AA), peptides, proteins, and photosynthetic pigments) [14]. In particular, N in the form of protein plays vital roles in most biological processes, such as enzymatic catalysis, transport and storage, immunity, and growth [14]. Meanwhile, dietary P supplies phosphate required for growth and metabolism, and constitutes phospholipids, nucleic acids, and ATP [14,15].…”

Bio‐energetic data show weak spatial but strong seasonal differences in wetland quality for waders in a Mediterranean migration bottleneck

“…Lipid content was determined by means of a Soxhlet extraction with petroleum ether as a solvent. Protein content was estimated using Kjeldahl analysis with a conversion factor of 6.25 to be multiplied with the number of nitrogen atoms (Diniz, Barbarino, Oiano, Pacheco, & Lourenço, 2014). Although it is sometimes considered to overestimate protein content in different animal products, this conversion factor was used to allow for comparison with other studies (Diniz et al., 2014; Mariotti, Tomé, & Patureau Mirand, 2008).…”

“…Protein content was estimated using Kjeldahl analysis with a conversion factor of 6.25 to be multiplied with the number of nitrogen atoms (Diniz, Barbarino, Oiano, Pacheco, & Lourenço, 2014). Although it is sometimes considered to overestimate protein content in different animal products, this conversion factor was used to allow for comparison with other studies (Diniz et al., 2014; Mariotti, Tomé, & Patureau Mirand, 2008). With the restriction of a minimum required mass of 2 g for each separate analysis, a maximum separation according to season, wetland area, and, if possible, sediment layer and taxon was put forward (Table SI.5 in Appendix S5).…”