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Journal of Applied Phycology

, Volume 28, Issue 1, pp 511–524 | Cite as

The protein content of seaweeds: a universal nitrogen-to-protein conversion factor of five

  • Alex R. AngellEmail author
  • Leonardo Mata
  • Rocky de Nys
  • Nicholas A. Paul
Article

Abstract

A global drive to source additional and sustainable biomass for the production of protein has resulted in a renewed interest in the protein content of seaweeds. However, to determine accurately the potential of seaweeds as a source of protein requires reliable quantitative methods. This article systematically analysed the literature to assess the approaches and methods of protein determination and to provide an evidence-based conversion factor for nitrogen to protein that is specific to seaweeds. Almost 95 % of studies on seaweeds determined protein either by direct extraction procedures (42 % of all studies) or by applying an indirect nitrogen-to-protein conversion factor of 6.25 (52 % of all studies), with the latter as the most widely used method in the last 6 years. Meta-analysis of the true protein content, defined as the sum of the proteomic amino acids, demonstrated that direct extraction procedures underestimated protein content by 33 %, while the most commonly used indirect nitrogen-to-protein conversion factor of 6.25 over-estimated protein content by 43 %. We therefore determined whether a single nitrogen-to-protein conversion factor could be used for seaweeds and evaluated how robust this would be by analysing the variation in this factor for 103 species across 44 studies that span three phyla, multiple geographic regions and a range of nitrogen contents. An overall median nitrogen-to-protein conversion factor of 4.97 was established and an overall mean nitrogen-to-protein conversion factor of 4.76. We propose that the overall median value of 5 be used as the most accurate universal seaweed nitrogen-to-protein (SNP) conversion factor.

Keywords

Amino acid Macroalgae Meta-analysis Nitrogen-to-protein factor Protein Protein determination Seaweed 

Notes

Acknowledgments

This research is part of the MBD Energy Research and Development programme for Biological Carbon Capture and Storage. The project is supported by the Advanced Manufacturing Cooperative Research Centre (AMCRC), funded through the Australian Government’s Cooperative Research Centre Scheme. We thank Simon Angell for developing an Excel macro program that enabled efficient extraction of data from the literature.

Supplementary material

10811_2015_650_MOESM1_ESM.tif (33.2 mb)
Figure S1 Number of papers identified through the review per year of publication as the sum of the three main extraction methods—Extraction, N × 6.25 and total amino acids (TAA). (TIFF 33974 kb)
10811_2015_650_Fig6_ESM.gif (34 kb)
High Resolution (GIF 34 kb)
10811_2015_650_MOESM2_ESM.tif (7.4 mb)
Figure S2 Nitrogen-to-protein conversion factors calculated for extraction and total amino acid (TAA) determination methods. Dashes represent medians, crosses represent means, boxes represent 25th percentiles and whiskers represent 5th/95th percentiles. The horizontal dashed line represents a ratio of 6.25. (TIFF 7622 kb)
10811_2015_650_Fig7_ESM.gif (9 kb)
High Resolution (GIF 9 kb)
10811_2015_650_MOESM3_ESM.tif (6.8 mb)
Figure S3 Quantitative tissue nitrogen measurements (% DW) of papers examined in this review analysed using the two main methods; analysis by combustion and by variants of the Kjeldahl method. Dashes represent medians, crosses represent means, boxes represent 25th percentiles and whiskers represent 5th/95th percentiles. (TIFF 6995 kb)
10811_2015_650_Fig8_ESM.gif (8 kb)
High Resolution (GIF 7 kb)
10811_2015_650_MOESM4_ESM.tif (7.9 mb)
Figure S4 Concentration of nitrogen in the total amino acid (TAA) and non-TAA fractions of seaweeds analysed for N-prot factors in this review. Dashes represent medians, crosses represent means, boxes represent 25th percentiles and whiskers represent 5th/95th percentiles. (TIFF 8079 kb)
10811_2015_650_Fig9_ESM.gif (9 kb)
High Resolution (GIF 9 kb)
10811_2015_650_MOESM5_ESM.tif (16.8 mb)
Figure S5 The within-species variation in (a) nitrogen-to-protein conversion factors and (b) the concentration of nitrogen in the total amino acid (TAA) and non-TAA fractions of the green seaweed Ulva ohnoi. All data is from Angell et al. (2014). Dashes represent medians, crosses represent means, boxes represent 25th percentiles and whiskers represent 5th/95th percentiles. (TIFF 17174 kb)
10811_2015_650_Fig10_ESM.gif (15 kb)
High Resolution (GIF 15 kb)
10811_2015_650_MOESM6_ESM.docx (15 kb)
Table S1 Descriptive statistics for protein content data (% DW) overall and for each categorisation. Data shown for all and each method of protein determination. (DOCX 14 kb)
10811_2015_650_MOESM7_ESM.docx (28 kb)
Table S2 Mean N-protein factors for all species examined (raw data) and those included in the 5th/95th percentile range which were used for analysis in this meta-analysis. Numbers in parenthesis indicate medians for N-protein factors. (DOCX 28 kb)
10811_2015_650_MOESM8_ESM.docx (16 kb)
Table S3 Correlations between N content and N-protein factor for all seaweeds overall and all possible sub-groups. r 2 values, direction and p value given. Bold text indicates a significant correlation (p < 0.05). Sub-groups not shown had no data available. (DOCX 16 kb)
10811_2015_650_MOESM9_ESM.docx (43 kb)
Appendix 1 Additional articles included in meta-analysis that were not retrieved by search string as well as the list of all articles examined in qualitative and quantitative meta-analysis. (DOCX 42 kb)

References

  1. Aitken K, Melton L, Brown M (1991) Seasonal protein variation in the New Zealand seaweeds Porphyra columbina Mont. & Porphyra subtumens J. Ag. (Rhodophyceae). Jap J Phycol 39:307–317Google Scholar
  2. Angell AR, Mata L, de Nys R, Paul NA (2014) Variation in amino acid content and its relationship to nitrogen content and growth rate in Ulva ohnoi (Chlorophyta). J Phycol 50:216–226CrossRefPubMedGoogle Scholar
  3. Angell AR, de Nys R, Paul NA (2015) The nitrogen, protein and amino acid content of seaweeds [data set]. doi: 10.4225/28/55776D6F45871
  4. Barbarino E, Lourenco SO (2005) An evaluation of methods for extraction and quantification of protein from marine macro- and microalgae. J Appl Phycol 17:447–460CrossRefGoogle Scholar
  5. Berges J, Fisher A, Harrison P (1993) A comparison of Lowry, Bradford and Smith protein assays using different protein standards and protein isolated from the marine diatom Thalassiosira pseudonana. Mar Biol 115:187–193CrossRefGoogle Scholar
  6. Boland MJ, Rae AN, Vereijken JM, Meuwissen MPM, Fischer ARH, van Boekel MAJS, Rutherfurd SM, Gruppen H, Moughan PJ, Hendriks WH (2012) The future supply of animal-derived protein for human consumption. Trends Food Sci Technol 29:62–73CrossRefGoogle Scholar
  7. Bradford MM (1976) A rapid and sensitive method for the quantitation of microgram quantities of protein utilizing the principle of protein-dye binding. Anal Biochem 72:248–254CrossRefPubMedGoogle Scholar
  8. Compton SJ, Jones CG (1985) Mechanism of dye response and interference in the Bradford protein assay. Anal Biochem 151:369–374CrossRefPubMedGoogle Scholar
  9. Craigie JS (2011) Seaweed extract stimuli in plant science and agriculture. J Appl Phycol 23:371–393CrossRefGoogle Scholar
  10. Crossman DJ, Clements KD, Cooper GJS (2000) Determination of protein for studies of marine herbivory: a comparison of methods. J Exp Mar Biol Ecol 244:45–65CrossRefGoogle Scholar
  11. Danell E, Eaker D (1992) Amino acid and total protein content of the edible mushroom Cantharellus cibarius (Fries). J Sci Food Agric 60:333–337CrossRefGoogle Scholar
  12. Darragh AJ, Moughan PJ (2005) The effect of hydrolysis time on amino acid analysis. J AOAC Int 88:888–893PubMedGoogle Scholar
  13. Dawes CJ, Lawrence JM, Cheney DP, Mathieso A, (1974) Ecological studies of floridian Eucheuma (Rhodophyta, Gigartinales).3. Seasonal variation of carrageenan, total carbohydrate, protein, and lipid. Bull Mar Sci 24:286–299Google Scholar
  14. Diniz GS, Barbarino E, Oiano-Neto J, Pacheco S, Lourenco SO (2011) Gross chemical profile and calculation of specific nitrogen-to-protein conversion factors for five tropical seaweeds. Am J Plant Sci 2:287–296CrossRefGoogle Scholar
  15. Fleurence J (1999a) The enzymatic degradation of algal cell walls: a useful approach for improving protein accessibility? J Appl Phycol 11:313–314CrossRefGoogle Scholar
  16. Fleurence J (1999b) Seaweed proteins: biochemical, nutritional aspects and potential uses. Trends Food Sci Tech 10:25–28CrossRefGoogle Scholar
  17. Fleurence J, LeCoeur C, Mabeau S, Maurice M, Landrein A (1995) Comparison of different extractive procedures for proteins from the edible seaweeds Ulva rigida and Ulva rotundata. J Appl Phycol 7:577–582CrossRefGoogle Scholar
  18. Fujihara S, Kasuga A, Aoyagi Y, Sugahara T (1995) Nitrogen-to-protein conversion factors for some common edible mushrooms. J Food Sci 60:1045–1047CrossRefGoogle Scholar
  19. Hanisak MD (1983) The nitrogen relationships of marine macroalgae. In: Carpenter EJ, Capone DG (eds) Nitrogen in the marine environment. Academic, New York, pp 699–730CrossRefGoogle Scholar
  20. Harnedy PA, FitzGerald RJ (2011) Bioactive proteins, peptides, and amino acids from macroalgae. J Phycol 47:218–232CrossRefPubMedGoogle Scholar
  21. Harrison PJ, Hurd CL (2001) Nutrient physiology of seaweeds: application of concepts to aquaculture. Cah Biol Mar 42:71–82Google Scholar
  22. Heidelbaugh ND, Huber CS, Bednarczyk JF, Smith MC, Rambaut PC, Wheeler HO (1975) Comparison of three methods for calculating protein content of foods. J Agr Food Chem 23:611–613CrossRefGoogle Scholar
  23. Hurd CL, Harrison PJ, Druehl LD (1996) Effect of seawater velocity on inorganic nitrogen uptake by morphologically distinct forms of Macrocystis integrifolia from wave-sheltered and exposed sites. Mar Biol 126:205–214CrossRefGoogle Scholar
  24. Lourenço SO, Barbarino E, De-Paula JC, da Pereira LO S, Marquez UML (2002) Amino acid composition, protein content and calculation of nitrogen-to-protein conversion factors for 19 tropical seaweeds. Phycol Res 50:233–241CrossRefGoogle Scholar
  25. Lourenço SO, Barbarino E, Lavín PL, Lanfer Marquez UM, Aidar E (2004) Distribution of intracellular nitrogen in marine microalgae: calculation of new nitrogen-to-protein conversion factors. Eur J Phycol 39:17–32CrossRefGoogle Scholar
  26. Lourenço SO, Barbarino E, Marquez UML, Aidar E (1998) Distribution of intracellular nitrogen in marine microalgae: basis for the calculation of specific nitrogen-to-protein conversion factors. J Phycol 34:798–811CrossRefGoogle Scholar
  27. Lowry OH, Rosebrough NJ, Farr AL, Randall RJ (1951) Protein measurement with the Folin phenol reagent. J Biol Chem 193:265–275PubMedGoogle Scholar
  28. Mariotti F, Tomé D, Mirand PP (2008) Converting nitrogen into protein—beyond 6.25 and Jones’ factors. Crit Rev Food Sci 48:177–184CrossRefGoogle Scholar
  29. Mattoo RL, Ishaq M, Saleemuddin M (1987) Protein assay by Coomassie brilliant blue G-250-binding method is unsuitable for plant tissues rich in phenols and phenolases. Anal Biochem 163:376–384CrossRefPubMedGoogle Scholar
  30. McGlathery KJ, Pedersen MF, Borum J (1996) Changes in intracellular nitrogen pools and feedback controls on nitrogen uptake in Chaetomorpha linum (Chlorophyta). J Phycol 32:393–401CrossRefGoogle Scholar
  31. Moher D, Liberati A, Tetzlaff J, Altman DG (2009) Preferred reporting items for systematic reviews and meta-analyses: the PRISMA Statement. Ann Intern Med 151:264–269CrossRefPubMedGoogle Scholar
  32. Mossé J (1990) Nitrogen-to-protein conversion factor for ten cereals and six legumes or oilseeds. A reappraisal of its definition and determination. Variation according to species and to seed protein content. J Agr Food Chem 38:18–24CrossRefGoogle Scholar
  33. Mossé J, Huet JC, Baudet J (1985) The amino acid composition of wheat grain as a function of nitrogen content. J Cereal Sci 3:115–130CrossRefGoogle Scholar
  34. Naldi M, Wheeler PA (1999) Changes in nitrogen pools in Ulva fenestrata (Chlorophyta) and Gracilaria pacifica (Rhodophyta) under nitrate and ammonium enrichment. J Phycol 35:70–77CrossRefGoogle Scholar
  35. Nelson TA, Haberlin K, Nelson AV, Ribarich H, Hotchkiss R, Van Alstyne KL, Buckingham L, Simunds DJ, Fredrickson K (2008) Ecological and physiological controls of species composition in green macroalgal blooms. Ecology 89:1287–1298CrossRefPubMedGoogle Scholar
  36. Neveux N, Magnusson M, Maschmeyer T, Nys R, Paul NA (2014) Comparing the potential production and value of high‐energy liquid fuels and protein from marine and freshwater macroalgae. GCB Bioenergy. doi: 10.1111/gcbb.12171 Google Scholar
  37. Rosell KG, Srivastava LM (1985) Seasonal variations in total nitrogen, carbon and amino-acids in Macrocystis integrifolia and Nereocystis luetkeana (Phaeophyta). J Phycol 21:304–309CrossRefGoogle Scholar
  38. Sharma HS, Fleming C, Selby C, Rao J, Martin T (2014) Plant biostimulants: a review on the processing of macroalgae and use of extracts for crop management to reduce abiotic and biotic stresses. J Appl Phycol 26:465–490CrossRefGoogle Scholar
  39. Shuuluka D, Bolton JJ, Anderson RJ (2013) Protein content, amino acid composition and nitrogen-to-protein conversion factors of Ulva rigida and Ulva capensis from natural populations and Ulva lactuca from an aquaculture system, in South Africa. J Appl Phycol 25:677–685CrossRefGoogle Scholar
  40. Sosulski FW, Imafidon GI (1990) Amino acid composition and nitrogen-to-protein conversion factors for animal and plant foods. J Agr Food Chem 38:1351–1356CrossRefGoogle Scholar
  41. Taylor MW, Barr NG, Grant CM, Rees TAV (2006) Changes in amino acid composition of Ulva intestinalis (Chlorophyceae) following addition of ammonium or nitrate. Phycologia 45:270–276CrossRefGoogle Scholar
  42. Tummers B (2006) DataThief III. http://datathief.org/
  43. Wong K, Cheung PC (2001) Influence of drying treatment on three Sargassum species. J Appl Phycol 13:43–50Google Scholar
  44. Wong PF, Tan LJ, Nawi H, AbuBakar S (2006) Proteomics of the red alga, Gracilaria changii (Gracilariales, Rhodophyta). J Phycol 42:113–120Google Scholar
  45. Yeoh H-H, Wee Y-C (1994) Leaf protein contents and nitrogen-to-protein conversion factors for 90 plant species. Food Chem 49:245–250CrossRefGoogle Scholar
  46. Yeoh HH, Truong VD (1996) Protein contents, amino acid compositions and nitrogen-to-protein conversion factors for cassava roots. J Sci Food Agric 70:51–54CrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media Dordrecht 2015

Authors and Affiliations

  • Alex R. Angell
    • 1
    Email author
  • Leonardo Mata
    • 1
  • Rocky de Nys
    • 1
  • Nicholas A. Paul
    • 1
  1. 1.MACRO – the Centre for Macroalgal Resources & Biotechnology, College of Marine and Environmental SciencesJames Cook UniversityTownsvilleAustralia

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