Anthropogenic CO2 emissions are the main contributors to climate change. Among the various efforts to reduce atmospheric CO2 levels, cultivation of microalgae is the most promising approach owing to ...its high photosynthetic rates and CO2 fixation efficiencies than terrestrial counterparts. However, the accurate quantification method of CO2 fixation during the cultivation of microalgae in photobioreactors (PBRs) is lacking. Present methods for the determination of CO2 fixation during microalgae cultivation include direct and indirect methods, where 79% of direct method studies of the bibliometric analysis compared to 21% of indirect method studies. Direct methods evaluate the carbon content in microalgae biomass using assumptive values, though it results in significant errors as high as 50% in quantifying the CO2 fixation. This can be improved by measuring the carbon contents using elemental and total organic carbon analysis. On the other hand, indirect methods quantify CO2 concentration at inlet and outlet of PBRs by using gas chromatography or infrared sensors. It is rather difficult to validate the accuracy of direct and indirect methods due to the lack of comparative works and analysis among the methods. Additionally, there are no current studies that provide in-depth discussion and perspectives on the CO2 fixation methods. Therefore, the main aim of this critical review is to analyse, contrast and discuss the differences as well as inaccuracies of direct and indirect microalgae CO2 fixation quantifications in PBRs. This is followed by the recommendations for further improvements, and standard guidance for future studies in applying appropriate CO2 fixation quantification methods.
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•A comprehensive guide for CO2 fixation in microalgae photobioreactors is discussed.•Microalgae CO2 fixation can be quantified by direct and indirect methods.•Direct methods quantify CO2 fixation via microalgae biomass carbon content.•Indirect methods quantify CO2 fixation by photobioreactor CO2 gas concentrations.•Identified the gaps and suggested methods for accurate CO2 fixation quantifications.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•Carotenoid and phenolics significantly correlated (p<0.05) to antioxidant activities.•Fucoxanthin and gallic acid were the lead compounds responsible for antioxidant activities.•Chaetoceros ...calcitrans and Isochrysis galbana had higher activities than the rest.
Natural antioxidants from sustainable sources are favoured to accommodate worldwide antioxidant demand. In addition to bioprospecting for natural and sustainable antioxidant sources, this study aimed to investigate the relationship between the bioactives (i.e. carotenoid and phenolic acids) and the antioxidant capacities in fucoxanthin‐producing algae. Total carotenoid, phenolic acid, fucoxanthin contents and fatty acid profile of six species of algae (five microalgae and one macroalga) were quantified followed by bioactivity evaluation using four antioxidant assays. Chaetoceros calcitrans and Isochrysis galbana displayed the highest antioxidant activity, followed by Odontella sinensis and Skeletonema costatum which showed moderate bioactivities. Phaeodactylum tricornutum and Saccharina japonica exhibited the least antioxidant activities amongst the algae species examined. Pearson correlation and multiple linear regression showed that both carotenoids and phenolic acids were significantly correlated (p<0.05) with the antioxidant activities, indicating the influence of these bioactives on the algal antioxidant capacities.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Antimicrobial resistance (AMR) in bacteria is a global health crisis due to the rapid emergence of multidrug-resistant bacteria and the lengthy development of new antimicrobials. In light of this, ...artificial intelligence in the form of machine learning has been viewed as a potential counter to delay the spread of AMR. With the aid of AI, there are possibilities to predict and identify AMR in bacteria efficiently. Furthermore, a combination of machine learning algorithms and lab testing can help to accelerate the process of discovering new antimicrobials. To date, many machine learning algorithms for antimicrobial-resistance discovery had been created and vigorously validated. Most of these algorithms produced accurate results and outperformed the traditional methods which relied on sequence comparison within a database. This mini-review will provide an updated overview of antimicrobial design workflow using the latest machine-learning antimicrobial discovery algorithms in the last 5 years. With this review, we hope to improve upon the current AMR identification and antimicrobial development techniques by introducing the use of AI into the mix, including how the algorithms could be made more effective.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
This study profiled the prevalence of extended-spectrum ß-lactamase-producing Escherichia coli (ESBL-EC) in the community and compared their resistome and genomic profiles with isolates from clinical ...patients through whole-genome sequencing.
Fecal samples from 233 community dwellers from Segamat, a town in southern Malaysia, were obtained between May through August 2018. Putative ESBL strains were screened and tested using antibiotic susceptibility tests. Additionally, eight clinical ESBL-EC were obtained from a hospital in the same district between June through October 2020. Whole-genome sequencing was then conducted on selected ESBL-EC from both settings (n = 40) for pan-genome comparison, cluster analysis, and resistome profiling.
A mean ESBL-EC carriage rate of 17.82% (95% CI: 10.48%- 24.11%) was observed in the community and was consistent across demographic factors. Whole-genome sequences of the ESBL-EC (n = 40) enabled the detection of multiple plasmid replicon groups (n = 28), resistance genes (n = 34) and virulence factors (n = 335), with no significant difference in the number of genes carried between the community and clinical isolates (plasmid replicon groups, p = 0.13; resistance genes, p = 0.47; virulence factors, p = 0.94). Virulence gene marker analysis detected the presence of extraintestinal pathogenic E. coli (ExPEC), uropathogenic E. coli (UPEC), and enteroaggregative E. coli (EAEC) in both the community and clinical isolates. Multiple blaCTX-M variants were observed, dominated by blaCTX-M-27 (n = 12), blaCTX-M-65 (n = 10), and blaCTX-M-15 (n = 9). The clinical and community isolates did not cluster together based on the pan-genome comparison, suggesting isolates from the two settings were clonally unrelated. However, cluster analysis based on carried plasmids, resistance genes and phenotypic susceptibility profiles identified four distinct clusters, with similar patterns between the community and clinical isolates.
ESBL-EC from the clinical and community settings shared similar resistome profiles, suggesting the frequent exchange of genetic materials through horizontal gene transfer.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Microalgae are photoautotrophic organisms in freshwater systems known to uptake and bioremediate arsenic, a heavy metal. In this study, we compared the growth and arsenic uptake of two microalgae ...strains,
Nostoc
and
Chlorella
, to determine their suitability for arsenic bioremediation. As compared to the control, our results showed that treatment with As (III) enhanced the
Nostoc
growth by approximately 15% when grown in the absence of phosphate. The highest bioconcentration factor of
Nostoc
at this treatment was 1463.6, whereas 0.10 mg L
−1
As (V) treatment improved the
Chlorella
growth by 25%, in the presence of phosphate. However, arsenic uptake reduced from 175.7 to 32.3 throughout the cultivation period for
Chlorella
.
This suggests that
Nostoc
has an upper advantage in the bioremediation of arsenic as compared to the
Chlorella
strain. To gain insights into the potential of
Nostoc
in arsenic bioremediation, we further conducted SEM analysis on the vegetative cell surface. The SEM results showed that As (III) disrupted the
Nostoc
vegetative cell surface and structure. Further to this, pathway analysis and polymerase chain reaction (PCR) were conducted to identify the potential arsenic pathway regulated by
Nostoc
. The primary As (III)-related pathways elucidated include the arsA transporter and arsD complex that require ATP and As (III) methylation to
S
-adenosylmethionine. The phosphate deficiency condition resulting in the inability to generate ATP caused As (III) could not be excreted from the
Nostoc
cells, potentially contributing to the high arsenic concentration accumulated under phosphate-depleted conditions. These insights contribute to understanding the efficacy of microalgae strains in freshwater arsenic bioremediation.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The application of hydrogen peroxide (H
2
O
2
) as a management tool to control
Microcystis
blooms has become increasingly popular due to its short lifetime and targeted action. H
2
O
2
increases ...intracellular reactive oxygen species resulting in oxidative stress and subsequently cell death. H
2
O
2
is naturally produced in freshwater bodies as a result of photocatalytic reactions between dissolved organic carbon and sunlight. Previously, some studies have suggested that this environmental source of H
2
O
2
selectively targets for toxigenic cyanobacteria strains in the genus
Microcystis
. Also, past studies only focused on the morphological and biochemical changes of H
2
O
2
-induced cell death in
Microcystis
with little information available on the effects of different H
2
O
2
concentrations on growth, esterase activity and membrane integrity. Therefore, this study investigated the effects of non-lethal (40–4000 nM) concentrations on percentage cell death; with a focus on sub-lethal (50 μM) and lethal (275 μM; 500 μM) doses of H
2
O
2
on growth, cells showing esterase activity and membrane integrity. The non-lethal dose experiment was part of a preliminary study. Results showed a dose- and time-dependent relationship in all three
Microcystis
strains post H
2
O
2
treatment. H
2
O
2
resulted in a significant increase in intracellular reactive oxygen species, decreased chlorophyll
a
content, decreased growth rate and esterase activity. Interestingly, at sub-lethal (50 μM H
2
O
2
treatment), percentage of dead cells in microcystin-producing strains was significantly higher (
p
< 0.05) than that in non-microcystin-producing strains at 72 h. These findings further cement our understanding of the influence of H
2
O
2
on different strains of
Microcystis
and its impact on membrane integrity and metabolic physiology: important to future toxic bloom control programmes.
•Both treatments inhibited cancer proliferation in a time and dose dependent manner.•FxRF treatment were effective in inducing apoptosis in HepG2 cells than crude extract.•Treatments stimulated ...regulation in cell signalling, apoptotic and antioxidant genes.
In this study, anti-proliferative effects of C. calcitrans extract and its fucoxanthin rich fraction (FxRF) were assessed on human liver HepG2 cancer cell line. Efficacy from each extract was determined by cytotoxicity assay, morphological observation, and cell cycle analysis. Mechanisms of action observed were evaluated using multiplex gene expression analysis. Results showed that CME and FxRF induced cytotoxicity to HepG2 cells in a dose and time-dependent manner. FxRF (IC50: 18.89 μg.mL−1) was found to be significantly more potent than CME (IC50: 87.5 μg.mL−1) (p < 0.05). Gene expression studies revealed that anti-proliferative effects in treated cells by C. calcitrans extracts were mediated partly through the modulation of numerous genes involved in cell signaling (AKT1, ERK1/2, JNK), apoptosis (BAX, BID, Bcl-2, APAF, CYCS) and oxidative stress (SOD1, SOD2, CAT). Overall, C. calcitrans extracts demonstrated effective intervention against HepG2 cancer cells where enhanced apoptotic activities were observed with increased fucoxanthin content.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Microencapsulation can improve carotenoid stability by slowing down degradation. Studies on the production and processing effects of microencapsulated carotenoids were reported in the past however ...long-term storage studies on fucoxanthin stability remains limited. This study investigated the effects of an eighteen-week storage period across four conditions on fucoxanthin derived from the diatom, Chaetoceros calcitrans. The fucoxanthin powders were prepared using two microencapsulation methods i.e., freeze drying and spray drying. Briefly, the microcapsules produced were stored in amber bottles under room temperature (25 °C) or refrigerated (4 °C) in the dark or in the presence of light. Samples were collected every two weeks where the physicochemical characteristics, carotenoid stability and antioxidant activity were evaluated. It was found that the freeze-dried microcapsule stored in 4 °C showed significantly (p < 0.05) better carotenoid retainment (7.5 times more) and antioxidant outcomes (3.5 times higher), as compared to the spray-dried microcapsule stored in 25 °C light. All microcapsules were found to be mainly comprised of the carotenoids fucaxanthin, dehydro fucoxanthin acetate, capsanthone, antheraxanthin, and celaxanthin. The major carotenoid identified was fucoxanthin where correlation studies showed it was responsible for the antioxidant activities and stability of the produced microcapsules. Overall, both freeze-dried and spray-dried fucoxanthin microcapsules followed a first-order kinetic degradation reaction and the recommended storage condition for fucoxanthin microcapsules was ranked as follows 4 °C (dark) > 25 °C (dark) > 40 °C (dark) > 25 °C (light). This finding offer useful insights into optimizing fucoxanthin microencapsulation methods, maintaining product quality during storage and distribution, and ensuring compliance with quality standards of fucoxanthin-based products available to consumers across the production and distribution chain.
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•Freeze drying was a suitable technology for fucoxanthin encapsulation.•The major carotenoid in the fucoxanthin-rich fraction (FxRF) is fucoxanthin.•Fucoxanthin microcapsules follows a first order degradation kinetics.•Microcapsules storage stability are in the order of 4 °C (dark), 25 °C (dark), 40 °C (dark), 25 °C (light).
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Microalgae are unicellular photosynthetic microorganisms that are commonly found in saline or freshwater environments. Over the years, microalgae represent promising sources of sustainable ...bioactivities with past literatures reflecting a growing interest in algae-based dietary supplements in the form of whole biomass. Notably, the bioactive molecules that can be identified and extracted in microalgae have scientifically proven to contain therapeutic properties which can be beneficial to human health. With the increasing occurrence of global health threats such as antimicrobial resistance and cancer, this has resulted in considerable attention for microalgae study especially in the medicinal field. Although studies have proved the therapeutic potentials of high-value bioproducts in microalgae, however, there is still room to understand their potential therapeutic properties on humans’ health, discovering novel microalgae-derived bioactive compounds, as well as translating the lab-based evidence to clinical trial studies. This review will focus on accessing the biochemical compositions of commercialised microalgae species from 2007 to 2020, and the activity of their biologically active molecules in eliciting selected therapeutic potentials which are anti-oxidative, anti-inflammatory, anti-microbial and anti-cancer properties. This review article will also be looking at the research gaps in addition to the above four major selected therapeutic potentials, and future prospective.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Cyanobacteria bioactive compounds are chemical treasure troves for product discovery and development. The wound healing effects and antioxidant capacities of water extracts from
Nostoc
...NIES-2111_MUM004 were evaluated via in vitro wound scratch assay and three antioxidant assays respectively. Results showed that the water extracts were protein-rich and exhibited good antioxidant properties in ABTS radical scavenging (11.27 ± 0.205 mg TAE g
−1
extract), Ferric reducing antioxidant power (1652.71 ± 110.71 mg TAE g
−1
extract) and β-carotene bleaching assay (354.90 ± 31.80 mg TAE g
−1
extract). Also, extracts were non-cytotoxic in concentrations up to 250 µg/mL as reflected in cytotoxicity assay. Importantly, water extracts showed considerable proliferation and migration activity at 125 µg/mL with wound closure rate as high as 42.67%. Statistical correlation revealed no significant relationship (
p
> 0.05) between protein fraction and the wound healing properties, confirming that phycobiliproteins were not solely responsible for wound healing activities. Subsequent Q-TOF-LCMS analysis identified six protein families involved in enhancing the proliferation and migration of epithelial cells. These findings are antecedent in the uncovering of continuous supplies of bioactive compounds from new and sustainable sources. Ultimately, enriching the microalgae menu for applications in pharmaceutical, nutraceutical and cosmeceuticals.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
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