Properties of microalgal enzymatic protein hydrolysates: Biochemical composition, protein distribution and FTIR characteristics (original) (raw)
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Utilisation of Chlorella vulgaris cell biomass for the production of enzymatic protein hydrolysates
Bioresource Technology, 2008
Studies on enzymatic hydrolysis of cell proteins in green microalgae Chlorella vulgaris 87/1 are described. Different proteases can be used for production of hydrolysates from ethanol extracted algae. The influence of reaction parameters on hydrolysis of extracted biomass with pancreatin was considered, and the composition of hydrolysates (Cv-PH) was investigated in relation to the starting materials. Significant changes in the degree of hydrolysis were observed only during the first 2 h and it remained constant throughout the process. An enzyme-substrate ratio of 30-45 units/g algae, an algae concentration of 10-15% and pH values of 7.5-8.0 could be recommended. Differences in the chromatographic patterns of Cv-PH and a hot-extract from Chlorella biomass were observed. Adequate amounts of essential amino acids (44.7%) in relation to the reference pattern of FAO for human nutrition were found, except for sulfur amino acids. Cv-PH could be considered as a potential ingredient in the food industry.
Journal of Taibah University for Science, 2023
Biomass production and biochemical composition in mass cultures of the marine microalga Zsochrysis galbana Parke at varying nutrient concentrations. Aquaculture, 53: 101-113. Mass cultures of Zsochrysis galbana were carried out with four nutrient concentrations ranging from 2 to 16 mM of NaNO, and salinity 35'&. An air flow of 15 l/min maintained a CO, transference rate sufficient to keep the pH below 8.4. Using these conditions, equations were calculated by a multiple non-linear least squares regression of order four, enabling predictions to be made of growth kinetics and chemical composition. Maximum cellular density of 65.5 X 10' cells/ml was obtained with 4 m&f NaNO,. Cellular volume was constant in the different nutrient concentrations. Protein content reached a maximum value of 374 pg/ml at 4 mhf of NaNO,, and this concentration also presented the maximum efficiency of transformation from nitrate to protein, i.e. 114%. As a result, lowest costs for harvesting are obtained at a nutrient concentration of 4 mM NaNO,. Efficiencies decreased to 15% as nutrient concentration increased. Maximum values of chlorophyll a (21.9 pg/ml) and carbohydrates (213 pg/ml) were also obtained with 4 mM NaNO,. In the logarithmic phase, the contents of protein, chlorophyll a, carbohydrates, RNA and DNA per cell were constant. Chlorophyll a reached values between 0.15 and 0.33 pg/cell in the stationary phase. Carbohydrate levels reached the maximum value of 3.16 pg/cell with 4 m&f NaNO, in the stationary phase. The levels of RNA/cell and DNA/cell were constant in all the nutrient concentrations tested and in both growth phases, and ranged from 1.15 to 1.71 pg/cell for RNA and from 0.006 to 0.014 pgfcell for DNA. Growth in mass cultures is closely coupled to changes in nutrient concentrations and variations occur in protein, chlorophyll a and carbohydrate contents, showing differences of 177%, 220% and 136%, respectively, in the stationary phase. This biochemical variability, mainly in protein content, must have a marked effect on the nutritive value of this microalga as a feed in mariculture.
Marine Drugs
Microalgae have been recently recognized as a promising alternative for the effective treatment of anaerobic digestion effluents. However, to date, a widely applied microalgae-based process is still absent, due to several constraints mainly attributed to high ammonia concentrations and turbidity, both hindering microalgal growth. Within this scope, the purpose of the present study was to investigate the performance of two Chlorella strains, SAG 211-11b and a local Algerian isolate, under different nitrogen levels, upon ammonia stripping. The experiments were performed on cylindrical photobioreactors under controlled pH (7.8 ± 0.2) and temperature (25 ± 2 °C). Cultures were monitored for biomass production and substrate consumption. After sampling at the beginning of the stationary phase of growth (12th day) and after the maturation of the cells (24th day), an analysis of the produced biomass was conducted, in terms of its biochemical components. The local isolate grew better than C....
Bulgarian Journal of Agricultural Science, 2018
VELICHKOVA, K. AND I. SIRAKOV, 2018. Growth parameters, protein and photosynthetic pigment content of Chlorella vulgaris cultivated under photoautotrophic and mixotrophic conditions. Bulg. J. Agric. Sci., 24 (Suppl. 1): 150–155 The purpose of this study was the determination of growth parameters, chlorophyll, carotenoid and protein content of the green microalgae Chlorella vulgaris cultivated under different mixotrophic and photoautotrophic conditions. Microalgae cultivation was initiated in a laboratory bioreactor of 500ml Erlenmeyer flask containing 250 ml nutrition media BBM. The cultures were maintained at room temperature (25-27oC) on a fluorescent light with a light:dark photoperiod of 12 h:12 h. The strains were checked for 96 hours growth period in photoautotrophic variants with carbon dioxide (2%, v/v), mixotrophic – CO2 + 3g.l -1 glucose, mixotrophic – CO2 + 3g.l -1 lactose. In the present study we found that C. vulgaris showed better growth in mixotrophic conditions with ...
Microalgal Biomass of Industrial Interest: Methods of Characterization
Handbook on Characterization of Biomass, Biowaste and Related By-products, 2020
Some of them have to be considered for characterizing biomass from some biomineralized microalgae, such as diatoms or calcareous species [38]. The large biodiversity and chemodiversity of microalgae is of great interest in tapping in never exploited natural molecules, thanks to recent and ongoing screening studies. However, such diversity implies that the standard analytical protocols for biomass characterization have to be critically examined for potential interference. Alga Class Protein content (%) Chlorella pyrenoidosa Trebouxiophyceae 57 Chlorella vulgaris 53.3 Chlorella ellipsoidea 42.2 Chlorella ovalis 10.97 Chlorellla spaerckii 6.87 Dunaliella salina Chlorophyceae Dunaliella primolecta 12.26 Dunaliella tertiolecta 11.4 Scenesdesmus obliquus Scenesdesmus almeriensis 41.8 Tetraselmis chui Chlorodendrophyceae 46.5 Porphyridium cruentum Porphyridiophyceae 35 Porphyridium aerugineum 31.6 4.3.1.2 Applications of algal protein 4.3.1.2.1 Human nutrition The nutritional quality of a protein is determined by the content, proportion and availability of its amino acids [50]. Four indices can be calculated to characterize the nutritional value of microalgae (Table 4.3.2): PER: Protein efficiency ratio, expressed in terms of weight gain per unit of protein consumed by the test animal in short-term feeding trials. BV: Biological value, a measure of nitrogen retained for growth and maintenance. DC: Digestibility coefficient NPU: Net protein utilisation (BV x DC), a measure of both the digestibility of the protein and the biological value of the amino acids absorbed from the food Cell walls of microalgae consist of a polysaccharide and glycoprotein matrix providing the cells with a formidable defense against its environment. It represents about 10 % of the algal dry matter and as it is non-digestible for humans and non-ruminants animals, a post-harvesting treatment of the microalgal cells is necessary to make the proteins accessible for digestive enzyme and can affect the various parameters (BV, DC, NPU and PER) (Table 4.3.2).
Journal of Chemical Technology & Biotechnology, 2015
BACKGROUND: The hard cell wall of some microalgae hampers efficient methane production when using those substrates. The present study investigated the effect of two groups of biocatalysts, namely carbohydrases and proteases, applied to Chlorella vulgaris and Scenedesmus sp. for microalgae hydrolysis prior to anaerobic digestion. RESULTS: Chlorella vulgaris subjected to protease activity resulted in higher organic matter solubilisation (47%) than the carbohydrase treated samples (25-29%). Out of the carbohydrases tested, maximum carbohydrate solubilisation was reached by applying Viscozyme (84% for C. vulgaris and 36% for Scenedesmus sp.). The anaerobic digestion assays revealed that biomasses hydrolyzed with protease reached the highest methane yield. In spite of the different macromolecular composition and behavior towards the biocatalysts, protease hydrolysis before anaerobic digestion enhanced methane yield 1.72-fold and 1.53-fold for C. vulgaris and Scenedesmus sp., respectively. CONCLUSION: Despite the common belief that carbohydrates are responsible for the low digestibility of microalgae, this study suggested that proteins were the main polymers hampering anaerobic digestion. The addition of enzymes to enhance anaerobic digestibility could be questionable economically-wise, however this investigation gives crucial information to elucidate the polymeric composition of two of the most common microalgae, C. vulgaris and Scenedesmus sp.
Algal Research, 2020
The aim of the study was to develop a sequential alkaline-enzymatic method to obtain protein-and/or amino acid-enriched extracts from fresh biomass of recalcitrant microalgae without any supplementary pretreatment. The effects of the initial biomass concentration, the use of freeze-dried or fresh biomass, enzyme dosage, processing procedure (two-step and single-step, with and without pH control) and species were studied. The method was evaluated with a consortium of microalgae isolated from a landfill leachate and was tested on other recognized recalcitrant microalgae such as Chlorella vulgaris, Nannochloropsis gaditana and Scenedesmus obliquus. The approach includes alternative pathways, provides high extraction yields of proteinaceous material and produces protein-and/or hydrolyzed peptide-enriched extracts with different amino acid compositions (e.g., a pathway without pH control achieves a yield of 81% of total protein and a concentration of 29 mg mL −1 of proteinaceous material). The versatility in processing procedures and the range of products obtained, along with applicability to different microalgal species, make this method an interesting option for algae biomass treatment. Furthermore, the high yield and simplicity from a technological point of view, gives it a great potential for process development and encourages further research for a wide variety of applications, such as feed, biostimulants, culture media, bulk chemicals, and biogas.