Gregory Martin

Towards sustainable microalgal biomass processing: anaerobic induction of autolytic cell-wall self-ingestion in lipid-rich Nannochloropsis slurries

Publisher: Royal Society of Chemistry (RSC)

Date: 2019

DOI: 10.1039/C8GC03186J

Abstract: Incubating Nannochloropsis slurries in darkness at 38 °C activated auto-fermentation metabolism that thinned cell walls and led to increased cell rupture.

The effect of nitrogen depletion on the cell size, shape, density and gravitational settling of Nannochloropsis salina, Chlorella sp. (marine) and Haematococcus pluvialis

Publisher: Elsevier BV

Date: 05-2019

DOI: 10.1016/J.ALGAL.2019.101454

The effects of acidic and thermal pretreatment on the mechanical rupture of two industrially relevant microalgae: Chlorella sp. and Navicula sp.

Publisher: Elsevier BV

Date: 2015

DOI: 10.1016/J.ALGAL.2014.11.006

Rheological properties of concentrated slurries of harvested, incubated and ruptured Nannochloropsis sp. cells

Publisher: Springer Science and Business Media LLC

Date: 08-05-2019

DOI: 10.1186/S42480-019-0011-Y

Effect of Bulk Viscosity and Emulsion Droplet Size on the Separation Efficiency of Model Mineral Oil-in-Water (O/W) Emulsions under Ultrasonic Standing Wave Fields: A Theoretical and Experimental Inve

Publisher: American Chemical Society (ACS)

Date: 02-04-2020

DOI: 10.1021/ACS.IECR.0C00616

Centrifugal recovery of solvent after biphasic wet extraction of lipids from a concentrated slurry of Nannochloropsis sp. biomass

Publisher: Elsevier BV

Date: 06-2017

DOI: 10.1016/J.ALGAL.2017.04.016

The CIDES process: Fractionation of concentrated microalgal paste for co-production of biofuel, nutraceuticals, and high-grade protein feed

Publisher: Elsevier BV

Date: 11-2016

DOI: 10.1016/J.ALGAL.2015.09.018

Ultrasonic encapsulation – A review

Publisher: Elsevier BV

Date: 03-2017

DOI: 10.1016/J.ULTSONCH.2016.03.017

Abstract: Encapsulation of materials in particles dispersed in water has many applications in nutritional foods, imaging, energy production and therapeutic/diagnostic medicine. Ultrasonic technology has been proven effective at creating encapsulating particles and droplets with specific physical and functional properties. Ex les include highly stable emulsions, functional polymeric particles with environmental sensitivity, and microspheres for encapsulating drugs for targeted delivery. This article provides an overview of the primary mechanisms arising from ultrasonics responsible for the formation of these materials, highlighting ex les that show promise particularly in the development of foods and bioproducts.

In silicostudy revealed the inhibitory activity of selected phytomolecules ofC. rotundusagainst VacA implicated in gastric ulcer

Publisher: Informa UK Limited

Date: 26-12-2022

DOI: 10.1080/07391102.2022.2160814

A study of the effectiveness and energy efficiency of ultrasonic emulsification

Publisher: Royal Society of Chemistry (RSC)

Date: 2017

DOI: 10.1039/C7CP07133G

Abstract: Theoretical and experimental aspects of the energy efficiency of ultrasonic emulsification were investigated and compared with conventional high-pressure homogenisation.

Nitrogen availability and the nature of extracellular organic matter of microalgae

Publisher: American Chemical Society (ACS)

Date: 06-01-2020

DOI: 10.1021/ACS.IECR.9B05426

Cellular toxicity and DNA damage induced by Newbouldia laevis used for male infertility treatment in prokaryotic and eukaryotic models

Publisher: Springer Science and Business Media LLC

Date: 13-07-2023

DOI: 10.1007/S00709-023-01880-4

A mechanistic study of algal cell disruption and its effect on lipid recovery by solvent extraction

Publisher: Elsevier BV

Date: 07-2014

DOI: 10.1016/J.ALGAL.2014.07.001

Ultrasound-induced protein restructuring and ordered aggregation to form amyloid crystals

Publisher: Springer Science and Business Media LLC

Date: 16-05-2022

DOI: 10.1007/S00249-022-01601-4

Abstract: Amyloid crystals, a form of ordered protein aggregates documented relatively recently, have not been studied as extensively as amyloid fibres. This study investigates the formation of amyloid crystals with low frequency ultrasound (20 kHz) using β-lactoglobulin, as a model protein for amyloid synthesis. Acoustic cavitation generates localised zones of intense shear, with extreme heat and pressure that could potentially drive the formation of amyloid structures at ambient bulk fluid temperatures (20 ± 1 °C). Thioflavin T fluorescence and electron microscopy showed that low-frequency ultrasound at 20 W/cm 3 input power induced β-stacking to produce amyloid crystals in the mesoscopic size range, with a mean length of approximately 22 µm. FTIR spectroscopy indicated a shift towards increased intermolecular antiparallel β-sheet content. An increase in sonication time (0–60 min) and input power (4–24 W/cm 3 ) increased the mean crystal length, but this increase was not linearly proportional to sonication time and input power due to the delayed onset of crystal growth. We propose that acoustic cavitation causes protein unfolding and aggregation and imparts energy to aggregates to cross the torsion barrier, to achieve their lowest energy state as amyloid crystals. The study contributes to a further understanding of protein chemistry relating to the energy landscape of folding and aggregation. Ultrasound presents opportunities for practical applications of amyloid structures, presenting a more adaptable and scalable approach for synthesis. Graphical abstract

Thermally coupled dark-anoxia incubation: A platform technology to induce auto-fermentation and thus cell-wall thinning in both nitrogen-replete and nitrogen-deplete Nannochloropsis slurries

Publisher: Elsevier BV

Date: 10-2019

DOI: 10.1016/J.BIORTECH.2019.121769

Abstract: Nitrogen-deprived Nannochloropsis cells invested their fixed carbon into the accumulation of triacylglycerol and cell wall cellulose (thickness of N-replete cell walls = 27.8 ± 5.8, N-deplete cell walls = 51.0 ± 10.2 nm). In this study, the effect of nitrogen depletion on the ability of the cells to weaken their own cell walls via autolysis was investigated. Autolytic cell wall thinning was achieved in both N-replete and N-deplete biomass by incubating highly concentrated slurries in darkness at 38 °C. The incubation forced cells to anaerobically ferment their intracellular cellulose and resulted in 30-40% reduction in cell wall thickness for both biomass types. This wall depletion weakened the cells and increased the extent of cell rupture by mechanical force (from 42 to 78% for N-replete biomass, from 36 to 62% for N-deplete biomass). Importantly, autolysis did not adversely impact the amino acid content of protein-rich N-replete biomass or the fatty acid content of lipid-rich N-deplete biomass.

Amino Acid and Secondary Structure Integrity of Sonicated Milk Proteins

Publisher: CSIRO Publishing

Date: 2020

DOI: 10.1071/CH19372

Abstract: This study investigated the effect of low-frequency (20kHz) and high-frequency (414kHz) ultrasound treatment on the amino acid and secondary structural integrity of dairy proteins. Sonicated skim milk proteins were hydrolysed and analysed with reverse-phase high-performance liquid chromatography to investigate the amino acid content of the processed s les. It was successfully demonstrated that both low-frequency and high-frequency ultrasound did not adversely affect the amino acid content, even after prolonged extreme processing conditions (6h, 355kHz). This finding was supplemented with protein secondary structure data (Fourier-transform (FT)-IR secondary derivatives of the amide I band, 1700–1600cm−1) that showed that ultrasound was capable of causing structural modifications to the dairy proteins. This study shows that ultrasound can be used to influence protein–protein interactions in skim milk via alterations to the secondary structure without degrading the amino acids in the proteins.

Bioaccessibility and bioactivities of phenolic compounds from microalgae during in vitro digestion and colonic fermentation

Publisher: Royal Society of Chemistry (RSC)

Date: 2023

DOI: 10.1039/D2FO02980D

Abstract: Conceptual framework of the microalgae in vitro digestion and colonic fermentation.

Wastewater treatment using filamentous algae – A review

Publisher: Elsevier BV

Date: 02-2020

DOI: 10.1016/J.BIORTECH.2019.122556

Abstract: Wastewater treatment using algae is a promising approach for efficient removal of contaminating nutrients and their conversion into useful products. Monocultures of filamentous algae provide easier harvesting compared to microalgae, and better control of biomass quality than polyculture systems such as algal turf scrubbers. In this review, recent research into wastewater treatment using freshwater filamentous algae is compiled and critically analysed. Focus is given to filamentous algae monocultures, with key relevant findings from microalgae and polyculture systems discussed and compared. The application of monocultures of filamentous algae is an emerging area of research. Gaps are identified in our understanding of key aspects important to large-scale system design, including criteria for species selection, influence of nutrient type and loading, inorganic carbon supply, algae-bacteria interactions, and parameters such as pond depth, mixing and harvesting regimes. This technology has much promise, however future research is needed to maximise productivity and wastewater treatment efficiency.

Preparation of water-in-oil-in-water emulsions by low frequency ultrasound using skim milk and sunflower oil

Publisher: Elsevier BV

Date: 02-2017

DOI: 10.1016/J.FOODHYD.2016.10.017

The assimilation of glycerol into lipid acyl chains and associated carbon backbones of Nannochloropsis salina varies under nitrogen replete and deplete conditions

Publisher: Wiley

Date: 28-07-2020

DOI: 10.1002/BIT.27498

Abstract: Mixotrophic cultivation can increase microalgae productivity, yet the associated lipid metabolism remains mostly unknown. Stable isotope labeling was used to track assimilation of glycerol into the triacylglyceride (TAG) and membrane lipids of Nannochloropsis salina. In N-replete media, glycerol uptake and

Extraction and Characterization of Bioactive Compounds from Diverse Marine Microalgae and Their Potential Antioxidant Activities

Publisher: Wiley

Date: 25-10-2023

DOI: 10.1002/CBDV.202300602

Ultrasound-Assisted Extracellular Polymeric Substance Removal from the Diatom Navicula sp.: A Route to Functional Polysaccharides and More Efficient Algal Biorefineries

Publisher: American Chemical Society (ACS)

Date: 24-01-2022

DOI: 10.1021/ACSSUSCHEMENG.1C06290

Cytogenotoxicity of the aqueous extract of Parquetina nigrescens leaf using Allium cepa assay

Publisher: Springer Science and Business Media LLC

Date: 10-02-2022

DOI: 10.1007/S00709-022-01741-6

Abstract: Parquetina nigrescens has been used for decades in ethnomedicine for its antioxidant, antimicrobial, anti-inflammatory, analgesic, and aphrodisiac properties. In this study, the cytotoxic and genotoxic effect of aqueous crude leaf extracts of P. nigrescens on the root meristematic cells of Allium cepa was examined. Volatile organic compounds (VOCs) present in the plant extract were also identified using gas chromatography-mass spectrometry (GC-MS). The extract was prepared with tap water as is locally practised by many Nigerians. Onion bulbs were exposed to 1, 5, 10, 20, and 50% concentrations of the extract for the analysis of root growth inhibition and chromosomal aberration. Lead nitrate (10 ppm) and tap water were used as the positive and negative controls, respectively. The result showed cytotoxicity which was observed as statistically significant (p <p0.05), concentration-dependent inhibition of root growth from 5 to 50% concentrations of the plant extract compared with the negative control. At 10 and 20% concentrations, the extract showed statistically significant (p < 0.05) genotoxicity by inducing different chromosomal aberrations such as fragments, disturbed spindle, delayed, and sticky chromosomes. The GC-MS analysis identified 14 VOCs of which 1, 2-benzenediol, 4H-pyran-4-one, 2, 3-dihydro-3,5-dihydroxy-6-methyl, and 5-hydroxymethylfurfural were believed to be responsible for the observed cytogenotoxicity. These results show that the aqueous crude leaf extracts of P. nigrescens at high concentrations are cytogenotoxic and therefore should be consumed with caution.

Protein fortification of model cheese matrices using whey protein-enriched double emulsions

Publisher: Elsevier BV

Date: 02-2023

DOI: 10.1016/J.FOODHYD.2022.108209

The effect of high-intensity ultrasound on cell disruption and lipid extraction from high-solids viscous slurries of Nannochloropsis sp. biomass

Publisher: Elsevier BV

Date: 11-2018

DOI: 10.1016/J.ALGAL.2018.09.004

Turbulence-dependent reversible liquid-gel transition of micellar casein-stabilised emulsions

Publisher: Elsevier BV

Date: 10-2022

DOI: 10.1016/J.FOODHYD.2022.107819

Emulsifying properties of ruptured microalgae cells: Barriers to lipid extraction or promising biosurfactants?

Publisher: Elsevier BV

Date: 10-2018

DOI: 10.1016/J.COLSURFB.2018.06.047

Abstract: A systematic investigation of the emulsifying properties of ruptured algae cells was performed for the first time. The slurry of ruptured algae cells was separated into different biomass fractions, namely the cell debris, the delipidated debris, the serum, and the lipid. The interfacial interactions of these biomass fractions with a nonpolar solvent (e.g. hexane or hexadecane) were characterized using pendant drop tensiometry and interfacial shear rheology. The stability of the different emulsions (formed by the different biomass fractions) was tested using analytical centrifugation. The extracted lipid was an excellent surfactant that reduced the interfacial tension, however, it was not effective at stabilizing the emulsions. The protein-rich serum produced a strong interfacial film that stabilized the emulsions against coalescence during centrifugation. The cell debris stabilized the emulsions to a lesser extent by adsorbing to the droplet surface, presumably via interactions with hydrophobic extracellular polymeric substances (EPS). However, neither the serum nor the cell debris were very effective surfactants, and required the presence of the lipid fraction to produce small emulsion droplets. When present together, the components exhibited competitive interfacial adsorption, which influenced emulsion stability. In particular, the interruption of the protein film by the presence of lipid or cell debris reduced the stability of the emulsions. This study provides a new mechanistic understanding of emulsification during wet lipid extraction from microalgae that will be useful for determining strategies to improve solvent recovery. The results also suggest potential for developing effective bioemulsifiers or biosurfactants from fractionated microalgae biomass for commercial application.

University Of Queensland

Location: Australia

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Linkage Projects - Grant ID: LP120100304

Start Date: 06-2012

End Date: 12-2015

Amount: $210,000.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP170103791

Start Date: 2017

End Date: 12-2019

Amount: $496,000.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP200101230

Start Date: 03-2020

End Date: 02-2023

Amount: $427,697.00

Funder: Australian Research Council

Industrial Transformation Research Hubs - Grant ID: IH210100051

Start Date: 07-2022

End Date: 07-2027

Amount: $5,000,000.00

Funder: Australian Research Council

Linkage Projects - Grant ID: LP190100090

Start Date: 09-2020

End Date: 09-2023

Amount: $531,000.00

Funder: Australian Research Council

Industrial Transformation Research Hubs - Grant ID: IH120100005

Start Date: 02-2014

End Date: 12-2019

Amount: $5,000,000.00

Funder: Australian Research Council

Linkage Projects - Grant ID: LP110200570

Start Date: 03-2012

End Date: 06-2016

Amount: $300,000.00

Funder: Australian Research Council