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Microalgae for Production of Bioproducts and Biofuels II

A special issue of Molecules (ISSN 1420-3049). This special issue belongs to the section "Green Chemistry".

Deadline for manuscript submissions: closed (31 December 2021) | Viewed by 6329

Special Issue Editors

Biotechnological Processes Unit, IMDEA Energy, 28040 Madrid, Spain
Interests: biotechnology; biofuel production; agricultural for energy source; energy production
Special Issues, Collections and Topics in MDPI journals
Bioenergy Unit, LNEG - National Laboratory of Energy and Geology, I.P., 1649-038 Lisbon, Portugal
Interests: microalgae; wastewater treatment; biofuels; biofertilizers; biostimulants; biopesticides; bioplastics; bioactive compounds; food; feed from microalgae
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear colleagues,

Microalgae have been recognized to possess great potential within the bioeconomy context. Although the total market size of algae bioproducts is still relatively small, the sector has undergone impressive growth. This can be seen by the big amount of research conducted in the field. After a first Special Issue published in 2020, we are thrilled to announce a second edition of the Special Issue in Molecules entitled “Microalgae for Production of Bioproducts and Biofuels II”.

The goal of this second edition is to highlight the significant progress in the research field of microalgae by paying special attention to issues that still need to be optimized. Among them, efficient and low-cost cultivation methods, harvesting and separation of the microalgal biomass from the culture medium, pre-treatment of the algal biomass to release its components for further conversion, and possible conversion processes to obtain biofuels and/or biocompounds are the focus of this second edition. This Special Issue invites manuscripts from authors who develop algae-related processes. Authors are invited to submit original research articles covering areas of cultivation, wastewater treatment, harvesting, biomass extraction, bioproducts, biofuels, biofertilizers, biostimulants and biorefinery approaches. Reviews that make substantial advances within this field are also invited to this Special Issue.

Dr. Cristina González-Fernandez
Dr. Luisa Gouveia
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Molecules is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2700 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Microalgae-based wastewater treatment
  • Biofuels
  • Bioactive-compounds
  • Biofertilizers/stimulants/pesticides
  • Bioproducts

Published Papers (3 papers)

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Research

13 pages, 2720 KiB  
Article
Impact of High-Pressure Homogenization on the Cell Integrity of Tetradesmus obliquus and Seed Germination
Molecules 2022, 27(7), 2275; https://doi.org/10.3390/molecules27072275 - 31 Mar 2022
Cited by 8 | Viewed by 1722
Abstract
Microalgae have almost unlimited applications due to their versatility and robustness to grow in different environmental conditions, their biodiversity and variety of valuable bioactive compounds. Wastewater can be used as a low-cost and readily available medium for microalgae, while the latter removes the [...] Read more.
Microalgae have almost unlimited applications due to their versatility and robustness to grow in different environmental conditions, their biodiversity and variety of valuable bioactive compounds. Wastewater can be used as a low-cost and readily available medium for microalgae, while the latter removes the pollutants to produce clean water. Nevertheless, since the most valuable metabolites are mainly located inside the microalga cell, their release implies rupturing the cell wall. In this study, Tetradesmus obliquus grown in 5% piggery effluent was disrupted using high-pressure homogenization (HPH). Effects of HPH pressure (100, 300, and 600 bar) and cycles (1, 2 and 3) were tested on the membrane integrity and evaluated using flow cytometry and microscopy. In addition, wheat seed germination trials were carried out using the biomass at different conditions. Increased HPH pressure or number of cycles led to more cell disruption (75% at 600 bar and 3 cycles). However, the highest increase in wheat germination and growth (40–45%) was observed at the lowest pressure (100 bar), where only 46% of the microalga cells were permeabilised, but not disrupted. Non-treated T. obliquus cultures also revealed an enhancing effect on root and shoot length (up to 40%). The filtrate of the initial culture also promoted shoot development compared to water (21%), reinforcing the full use of all the process fractions. Thus, piggery wastewater can be used to produce microalgae biomass, and mild HPH conditions can promote cell permeabilization to release sufficient amounts of bioactive compounds with the ability to enhance plant germination and growth, converting an economic and environmental concern into environmentally sustainable applications. Full article
(This article belongs to the Special Issue Microalgae for Production of Bioproducts and Biofuels II)
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19 pages, 2030 KiB  
Article
Growth Performance, Biochemical Composition and Nutrient Recovery Ability of Twelve Microalgae Consortia Isolated from Various Local Organic Wastes Grown on Nano-Filtered Pig Slurry
Molecules 2022, 27(2), 422; https://doi.org/10.3390/molecules27020422 - 10 Jan 2022
Cited by 5 | Viewed by 1634
Abstract
This paper demonstrated the growth ability of twelve algae-microbial consortia (AC) isolated from organic wastes when a pig slurry-derived wastewater (NFP) was used as growth substrate in autotrophic cultivation. Nutrient recovery, biochemical composition, fatty acid and amino acid profiles of algae consortia were [...] Read more.
This paper demonstrated the growth ability of twelve algae-microbial consortia (AC) isolated from organic wastes when a pig slurry-derived wastewater (NFP) was used as growth substrate in autotrophic cultivation. Nutrient recovery, biochemical composition, fatty acid and amino acid profiles of algae consortia were evaluated and compared. Three algae-microbial consortia, i.e., a Chlorella-dominated consortium (AC_1), a Tetradesmus and Synechocystis co-dominated consortium (AC_10), and a Chlorella and Tetradesmus co-dominated consortium (AC_12) were found to have the best growth rates (µ of 0.55 ± 0.04, 0.52 ± 0.06, and 0.58 ± 0.03 d−1, respectively), which made them good candidates for further applications. The ACs showed high carbohydrates and lipid contents but low contents of both proteins and essential amino acids, probably because of the low N concentration of NFP. AC_1 and AC_12 showed optimal ω6:ω3 ratios of 3.1 and 3.6, which make them interesting from a nutritional point of view. Full article
(This article belongs to the Special Issue Microalgae for Production of Bioproducts and Biofuels II)
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15 pages, 3995 KiB  
Article
Photoautotrophic and Mixotrophic Cultivation of Polyhydroxyalkanoate-Accumulating Microalgae Consortia Selected under Nitrogen and Phosphate Limitation
Molecules 2021, 26(24), 7613; https://doi.org/10.3390/molecules26247613 - 15 Dec 2021
Cited by 3 | Viewed by 2066
Abstract
Microalgae consortia were photoautotrophically cultivated in sequencing batch photobioreactors (SBPRs) with an alteration of the normal growth and starvation (nutrient limitation) phases to select consortia capable of polyhydroxyalkanoate (PHA) accumulation. At the steady state of SBPR operation, the obtained microalgae consortia, selected under [...] Read more.
Microalgae consortia were photoautotrophically cultivated in sequencing batch photobioreactors (SBPRs) with an alteration of the normal growth and starvation (nutrient limitation) phases to select consortia capable of polyhydroxyalkanoate (PHA) accumulation. At the steady state of SBPR operation, the obtained microalgae consortia, selected under nitrogen and phosphate limitation, accumulated up to 11.38% and 10.24% of PHA in their biomass, which was identified as poly(3-hydroxybutyrate) (P3HB). Photoautotrophic and mixotrophic batch cultivation of the selected microalgae consortia was conducted to investigate the potential of biomass and PHA production. Sugar source supplementation enhanced the biomass and PHA production, with the highest PHA contents of 10.94 and 6.2%, and cumulative PHA productions of 100 and 130 mg/L, with this being achieved with sugarcane juice under nitrogen and phosphate limitation, respectively. The analysis of other macromolecules during batch cultivation indicated a high content of carbohydrates and lipids under nitrogen limitation, while higher protein contents were detected under phosphate limitation. These results recommended the selected microalgae consortia as potential tools for PHA and bioresource production. The mixed-culture non-sterile cultivation system developed in this study provides valuable information for large-scale microalgal PHA production process development following the biorefinery concept. Full article
(This article belongs to the Special Issue Microalgae for Production of Bioproducts and Biofuels II)
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