scholarly journals Extracellular Polymeric Substances (EPS) as Microalgal Bioproducts: A Review of Factors Affecting EPS Synthesis and Application in Flocculation Processes

Energies ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 4007
Author(s):  
Wioleta Babiak ◽  
Izabela Krzemińska

Microalgae are natural resources of intracellular compounds with a wide spectrum of applications in, e.g., the food industry, pharmacy, and biofuel production. The extracellular polymeric substances (EPS) released by microalgal cells are a valuable bioproduct. Polysaccharides, protein, lipids, and DNA are the main constituents of EPS. This review presents the recent advances in the field of the determinants of the synthesis of extracellular polymeric substances by microalgal cells and the EPS structure. Physical and chemical culture conditions have been analyzed to achieve useful insights into the development of a strategy optimizing EPS production by microalgal cells. The application of microalgal EPS for flocculation and mechanisms involved in this process are also discussed in terms of biomass harvesting. Additionally, the ability of EPS to remove toxic heavy metals has been analyzed. With their flocculation and sorption properties, microalgal EPS are a promising bioproduct that can potentially be used in harvesting algal biomass and wastewater management.

2020 ◽  
Author(s):  
Mariana Barbalho Silva ◽  
Edwin G. Azero ◽  
Cláudia M. L. L. Teixeira ◽  
Cristina T. Andrade

Abstract Arthrospira platensis is a cyanobacterium that exhibits a large biotechnological interest for the food industry because of its high protein content, pigments, lipids and carbohydrates. The extracellular polymeric substances (EPS) are co-products of secondary metabolism that may present thickening or gelling property. A 3-level factorial design was used to study the combined effect of different nitrate concentrations and photon flux density (PFD) to evaluate the biomass and EPS production by Arthrospira platensis. The best result for biomass production was obtained under condition 6 (2 g.L-1 NaNO3 and 600 µE.m-2s-1) leading a biomass concentration of 1.292 mg.L-1. Condition 1 (0.25 g.L-1NaNO3 and 200 µE.m-2s-1) produced the major EPS yield (111 mg.g-1) followed by condition 9 (2 g.L-1NaNO3 and 1000 µE.m-2s-1). The present of carboxylate and sulfate functional groups was identified in EPS samples. Rheological studies performed for some EPS products at 5 and 10 g.L-1 concentrations revealed a dilute solution behavior.


2020 ◽  
Author(s):  
Mariana Barbalho Silva ◽  
Edwin G. Azero ◽  
Cláudia M. L. L. Teixeira ◽  
Cristina T. Andrade

Abstract Arthrospira platensis is a cyanobacterium that is of great biotechnological interest, particularly for the food industry, as it possesses a high content of proteins, pigments, lipids and carbohydrates. Cyanobacteria produce extracellular polymeric substances (EPS), which are co-products of secondary metabolism that present thickening or gelling properties. A 3-level factorial design was used to study the combined effect of different nitrate concentrations and photon flux density (PFD) values to evaluate the biomass and EPS production of A. platensis. The best result in terms of biomass production was obtained under condition 6 (2 g.L-1 NaNO3 and 600 μE.m-2.s-1) yielding a concentration of 1.292 g.L-1. However, condition 1 (0.25 g.L-1 NaNO3 and 200 μE.m-2.s-1) produced the greatest EPS yield (111 mg.g-1), followed by condition 9 (2 g.L-1 NaNO3 and 1000 μE.m-2.s-1). FTIR analyses of EPS samples indicated the presence of carboxylate and sulfate functional groups, and rheological studies of the EPS at 5 and 10 g.L-1 revealed a dilute solution behavior.


2020 ◽  
Author(s):  
Mariana Barbalho Silva ◽  
Edwin G. Azero ◽  
Cláudia M. L. L. Teixeira ◽  
Cristina T. Andrade

Abstract Arthrospira platensis is a cyanobacterium that exhibits a large biotechnological interest at food industry because its high protein content, pigments, lipids and carbohydrates. The extracellular polymeric substances (EPS) are co-products of secondary metabolism that present thickening or gelling property. A 3-level factorial design was used to study the combined effect of different nitrate concentrations and photon flux density (PFD) to evaluate the biomass and EPS production by Arthrospira platensis. Characterization of the EPS produced the rheological behavior were also evaluated. The best result for biomass production was obtained at condition 6 (2 g.L-1 NaNO3 and 600 µE.m-2s-1) leading a biomass concentration of 1.292 mg.L-1. Condition 1 (0.25 g.L-1NaNO3 and 200 µE.m-2s-1) produce the major EPS content (111 mg.g-1) followed by condition 9 (2 g.L-1NaNO3 and 1000 µE.m-2s-1). Rheological studies performed for the product at 5 and 10g.L-1 concentrations revealed a dilute solution behavior.


2018 ◽  
Vol 24 (21) ◽  
pp. 2425-2431 ◽  
Author(s):  
Cao Wu ◽  
Zhou Chen ◽  
Ya Hu ◽  
Zhiyuan Rao ◽  
Wangping Wu ◽  
...  

Crystallization is a significant process employed to produce a wide variety of materials in pharmaceutical and food area. The control of crystal dimension, crystallinity, and shape is very important because they will affect the subsequent filtration, drying and grinding performance as well as the physical and chemical properties of the material. This review summarizes the special features of crystallization technology and the preparation methods of nanocrystals, and discusses analytical technology which is used to control crystal quality and performance. The crystallization technology applications in pharmaceutics and foods are also outlined. These illustrated examples further help us to gain a better understanding of the crystallization technology for pharmaceutics and foods.


2021 ◽  
Vol 13 (12) ◽  
pp. 6921
Author(s):  
Laura Sisti ◽  
Annamaria Celli ◽  
Grazia Totaro ◽  
Patrizia Cinelli ◽  
Francesca Signori ◽  
...  

In recent years, the circular economy and sustainability have gained attention in the food industry aimed at recycling food industrial waste and residues. For example, several plant-based materials are nowadays used in packaging and biofuel production. Among them, by-products and waste from coffee processing constitute a largely available, low cost, good quality resource. Coffee production includes many steps, in which by-products are generated including coffee pulp, coffee husks, silver skin and spent coffee. This review aims to analyze the reasons why coffee waste can be considered as a valuable source in recycling strategies for the sustainable production of bio-based chemicals, materials and fuels. It addresses the most recent advances in monomer, polymer and plastic filler productions and applications based on the development of viable biorefinery technologies. The exploration of strategies to unlock the potential of this biomass for fuel productions is also revised. Coffee by-products valorization is a clear example of waste biorefinery. Future applications in areas such as biomedicine, food packaging and material technology should be taken into consideration. However, further efforts in techno-economic analysis and the assessment of the feasibility of valorization processes on an industrial scale are needed.


Molecules ◽  
2021 ◽  
Vol 26 (13) ◽  
pp. 3870
Author(s):  
Jingyang Li ◽  
Fei Liu ◽  
Hua Yu ◽  
Yuqi Li ◽  
Shiguang Zhou ◽  
...  

Banana is a major fruit crop throughout the world with abundant lignocellulose in the pseudostem and rachis residues for biofuel production. In this study, we collected a total of 11 pseudostems and rachis samples that were originally derived from different genetic types and ecological locations of banana crops and then examined largely varied edible carbohydrates (soluble sugars, starch) and lignocellulose compositions. By performing chemical (H2SO4, NaOH) and liquid hot water (LHW) pretreatments, we also found a remarkable variation in biomass enzymatic saccharification and bioethanol production among all banana samples examined. Consequently, this study identified a desirable banana (Refen1, subgroup Pisang Awak) crop containing large amounts of edible carbohydrates and completely digestible lignocellulose, which could be combined to achieve the highest bioethanol yields of 31–38% (% dry matter), compared with previously reported ones in other bioenergy crops. Chemical analysis further indicated that the cellulose CrI and lignin G-monomer should be two major recalcitrant factors affecting biomass enzymatic saccharification in banana pseudostems and rachis. Therefore, this study not only examined rich edible carbohydrates for food in the banana pseudostems but also detected digestible lignocellulose for bioethanol production in rachis tissue, providing a strategy applicable for genetic breeding and biomass processing in banana crops.


1934 ◽  
Vol 25 (4) ◽  
pp. 491-494 ◽  
Author(s):  
P. A. Buxton

During the last decade, entomologists have made progress in understanding the environment in which certain insects live; in particular, we begin to understand the effect of certain physical and chemical factors, which make up a part of the environment. With this gain in knowledge, it is sometimes possible to forecast outbreaks of insects and of diseases conveyed by them, and one can sometimes say that a particular alteration of the environment will result in loss or gain. But so far as mosquitos are concerned, one must admit that though much work has been devoted to the analytical study of the water in which the early stages are passed, the results are disappointing. A consideration of the published work suggests several reasons for this. Investigation into the ecology of the mosquito has had a vogue, and much of it has been done by workers who were isolated and whose knowledge of chemical technique and freshwater biology was limited. Apart from that, the inherent difficulties are great, for the worker must hunt for the limiting chemical and physical factors among a host of others which are doubtless unimportant, and there are few clues to indicate which of the chemical constituents of the water affects the mosquito. The data are therefore voluminous and it is difficult to reduce them to order and present them so that they can be readily understood.


2013 ◽  
Vol 41 (1) ◽  
pp. 393-398 ◽  
Author(s):  
Sabrina Fröls

Biofilms or multicellular structures become accepted as the dominant microbial lifestyle in Nature, but in the past they were only studied extensively in bacteria. Investigations on archaeal monospecies cultures have shown that many archaeal species are able to adhere on biotic and abiotic surfaces and form complex biofilm structures. Biofilm-forming archaea were identified in a broad range of extreme and moderate environments. Natural biofilms observed are mostly mixed communities composed of archaeal and bacterial species of various abundances. The physiological functions of the archaea identified in such mixed communities suggest a significant impact on the biochemical cycles maintaining the flow and recycling of the nutrients on earth. Therefore it is of high interest to investigate the characteristics and mechanisms underlying the archaeal biofilm formation. In the present review, I summarize and discuss the present investigations of biofilm-forming archaeal species, i.e. their diverse biofilm architectures in monospecies or mixed communities, the identified EPSs (extracellular polymeric substances), archaeal structures mediating surface adhesion or cell–cell connections, and the response to physical and chemical stressors implying that archaeal biofilm formation is an adaptive reaction to changing environmental conditions. A first insight into the molecular differentiation of cells within archaeal biofilms is given.


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