scholarly journals Green Microalgae Strain Improvement for the Production of Sterols and Squalene

Plants ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 1673
Author(s):  
Supakorn Potijun ◽  
Suparat Jaingam ◽  
Nuttha Sanevas ◽  
Srunya Vajrodaya ◽  
Anchalee Sirikhachornkit
Keyword(s):  
Strain Improvement ◽  
Product Yield ◽  
Sterol Synthesis ◽  
Squalene Epoxidase ◽  
Green Microalgae ◽  
Uv Mutagenesis ◽  
Beneficial Effects ◽  
Green Microalga ◽  
Squalene Content ◽  
Resistant Strains

Sterols and squalene are essential biomolecules required for the homeostasis of eukaryotic membrane permeability and fluidity. Both compounds have beneficial effects on human health. As the current sources of sterols and squalene are plant and shark oils, microalgae are suggested as more sustainable sources. Nonetheless, the high costs of production and processing still hinder the commercialization of algal cultivation. Strain improvement for higher product yield and tolerance to harsh environments is an attractive way to reduce costs. Being an intermediate in sterol synthesis, squalene is converted to squalene epoxide by squalene epoxidase. This step is inhibited by terbinafine, a commonly used antifungal drug. In yeasts, some terbinafine-resistant strains overproduced sterols, but similar microalgae strains have not been reported. Mutants that exhibit greater tolerance to terbinafine might accumulate increased sterols and squalene content, along with the ability to tolerate the drug and other stresses, which are beneficial for outdoor cultivation. To explore this possibility, terbinafine-resistant mutants were isolated in the model green microalga Chlamydomonas reinhardtii using UV mutagenesis. Three mutants were identified and all of them exhibited approximately 50 percent overproduction of sterols. Under terbinafine treatment, one of the mutants also accumulated around 50 percent higher levels of squalene. The higher accumulation of pigments and triacylglycerol were also observed. Along with resistance to terbinafine, this mutant also exhibited higher resistance to oxidative stress. Altogether, resistance to terbinafine can be used to screen for strains with increased levels of sterols or squalene in green microalgae without growth compromise.

Microencapsulation: A Prospective to Protect Probiotics

2020 ◽  
Vol 16 (6) ◽  
pp. 891-899 ◽  
Author(s):  
Wissam Zam
Keyword(s):  
Gastrointestinal Tract ◽  
Food Industry ◽  
Health Benefits ◽  
Probiotic Bacteria ◽  
Bacterial Cells ◽  
Beneficial Effects ◽  
Host Health ◽  
Resistant Strains ◽  
Selection Of

Probiotics are viable microorganisms widely used for their claimed beneficial effects on the host health. A wide number of researchers proved that the intake of probiotic bacteria has numerous health benefits which created a big market of probiotic foods worldwide. The biggest challenge in the development of these products is to maintain the viability of bacterial cells during the storage of the product as well as throughout the gastrointestinal tract transit after consumption, so that the claimed health benefits can be delivered to the consumer. Different approaches have been proposed for increasing the resistance of these sensitive microorganisms, including the selection of resistant strains, incorporation of micronutrients, and most recently the use of microencapsulation techniques. Microencapsulation has resulted in enhancing the viability of these microorganisms which allows its wide use in the food industry. In this review, the most common techniques used for microencapsulation of probiotics will be presented, as well as the most usual microcapsule shell materials.

scholarly journals Application of Microalgal Stress Responses in Industrial Microalgal Production Systems

Marine Drugs ◽  
2021 ◽  
Vol 20 (1) ◽  
pp. 30
Author(s):  
Jia Wang ◽  
Yuxin Wang ◽  
Yijian Wu ◽  
Yuwei Fan ◽  
Changliang Zhu ◽  
...  
Keyword(s):  
Stress Responses ◽  
Production Systems ◽  
Strain Improvement ◽  
Value Added ◽  
Product Yield ◽  
Adaptive Laboratory Evolution ◽  
Laboratory Evolution ◽  
Theoretical Support ◽  
Further Development ◽  
Value Added Products

Adaptive laboratory evolution (ALE) has been widely utilized as a tool for developing new biological and phenotypic functions to explore strain improvement for microalgal production. Specifically, ALE has been utilized to evolve strains to better adapt to defined conditions. It has become a new solution to improve the performance of strains in microalgae biotechnology. This review mainly summarizes the key results from recent microalgal ALE studies in industrial production. ALE designed for improving cell growth rate, product yield, environmental tolerance and wastewater treatment is discussed to exploit microalgae in various applications. Further development of ALE is proposed, to provide theoretical support for producing the high value-added products from microalgal production.

scholarly journals Intrinsic resistance to terbinafine among human and animal isolates of Trichophyton mentagrophytes related to amino acid substitution in the squalene epoxidase

Infection ◽  
2020 ◽  
Vol 48 (6) ◽  
pp. 889-897 ◽  
Author(s):  
Dominik Łagowski ◽  
Sebastian Gnat ◽  
Aneta Nowakiewicz ◽  
Marcelina Osińska ◽  
Mariusz Dyląg
Keyword(s):  
Amino Acid ◽  
Fungal Infections ◽  
Single Point ◽  
Antifungal Susceptibility ◽  
Point Mutations ◽  
Trichophyton Mentagrophytes ◽  
Single Amino Acid ◽  
Squalene Epoxidase ◽  
Intrinsic Resistance ◽  
Resistant Strains

Abstract Background Dermatomycoses are the most common fungal infections in the world affecting a significant part of the human and animal population. The majority of zoophilic infections in humans are caused by Trichophyton mentagrophytes. Currently, the first-line drug for both oral and topical therapy is terbinafine. However, an increasing number of cases that are difficult to be cured with this drug have been noted in Europe and Asia. Resistance to terbinafine and other allylamines is very rare and usually correlated with point mutations in the squalene epoxidase gene resulting in single amino acid substitutions in the enzyme, which is crucial in the ergosterol synthesis pathway. Purpose Here, we report terbinafine-resistant T. mentagrophytes isolates among which one was an etiological factor of tinea capitis in a man and three were obtained from asymptomatic foxes in Poland. Methods We used the CLSI protocol to determine antifungal susceptibility profiles of naftifine, amphotericin B, griseofulvin, ketoconazole, miconazole, itraconazole, voriconazole, and ciclopirox. Moreover, the squalene epoxidase gene of the terbinafine-resistant strains was sequenced and analysed. Results In the genomes of all four resistant strains exhibiting elevated MICs to terbinafine (16 to 32 µg/ml), single-point mutations leading to Leu393Phe substitution in the squalene epoxidase enzyme were revealed. Among the other tested substances, a MIC50 value of 1 µg/ml was shown only for griseofulvin. Conclusion Finally, our study revealed that the terbinafine resistance phenomenon might not be acquired by exposure to the drug but can be intrinsic. This is evidenced by the description of the terbinafine-resistant strains isolated from the asymptomatic animals.

scholarly journals Disruption of the Candida albicans CYB5 Gene Results in Increased Azole Sensitivity

2004 ◽  
Vol 48 (9) ◽  
pp. 3425-3435 ◽  
Author(s):  
K. M. Rogers ◽  
C. A. Pierson ◽  
N. T. Culbertson ◽  
C. Mo ◽  
A. M. Sturm ◽  
...  
Keyword(s):  
Candida Albicans ◽  
Sterol Synthesis ◽  
Squalene Epoxidase ◽  
Gene Products ◽  
Direct Transformation ◽  
Azole Antifungals ◽  
Increased Sensitivity ◽  
Sterol Profile ◽  
Encoding Gene ◽  
Cytochrome P 450

ABSTRACT Sterol synthesis in fungi is an aerobic process requiring molecular oxygen and, for several cytochrome-mediated reactions, aerobically synthesized heme. Cytochrome b 5 is required for sterol C5-6 desaturation and the encoding gene, CYB5, is nonessential in Saccharomyces cerevisiae. Cyb5p and Ncp1p (cytochrome P-450 reductase) appear to have overlapping functions in this organism, with disruptions of each alone being viable. The cytochrome P-450 reductase phenotype has also been shown to demonstrate increased sensitivity to azole antifungals. Based on this phenotype, the CYB5 gene in the human pathogen Candida albicans was investigated to determine whether the cyb5 genotype was viable and would also demonstrate azole sensitivity. Sequential disruption of the CYB5 alleles by direct transformation resulted in viability, presumably conferred by the presence of a third copy of the CYB5 gene. Subsequent disruption procedures with a pMAL2-CYB5 rescue cassette and a CYB5-URA3 blaster cassette resulted in viable cyb5 strains with no third copy. The C. albicans CYB5 gene is concluded to be nonessential. Thus, the essentiality of this gene and whether we observed two or three alleles was dependent upon the gene disruption protocol. The C. albicans cyb5 strains produced a sterol profile containing low ergosterol levels and sterol intermediates similar to that reported for the S. cerevisiae cyb5. The C. albicans cyb5 shows increased sensitivity to azoles and terbinafine, an inhibitor of squalene epoxidase, and, unexpectedly, increased resistance to morpholines, which inhibit the ERG2 and ERG24 gene products. These results indicate that an inhibitor of Cyb5p would not be lethal but would make the cell significantly more sensitive to azole treatment.

scholarly journals HDL inhibits endoplasmic reticulum stress-induced apoptosis of pancreatic β-cells in vitro by activation of Smoothened

2020 ◽  
Vol 61 (4) ◽  
pp. 492-504 ◽  
Author(s):  
Mustafa Yalcinkaya ◽  
Anja Kerksiek ◽  
Katrin Gebert ◽  
Wijtske Annema ◽  
Rahel Sibler ◽  
...  
Keyword(s):  
Er Stress ◽  
Cell Apoptosis ◽  
Cell Mass ◽  
Sterol Synthesis ◽  
Atpase Inhibitor ◽  
Β Cells ◽  
Β Cell ◽  
Beneficial Effects ◽  
Hh Signaling

Loss of pancreatic β-cell mass and function as a result of sustained ER stress is a core step in the pathogenesis of diabetes mellitus type 2. The complex control of β-cells and insulin production involves hedgehog (Hh) signaling pathways as well as cholesterol-mediated effects. In fact, data from studies in humans and animal models suggest that HDL protects against the development of diabetes through inhibition of ER stress and β-cell apoptosis. We investigated the mechanism by which HDL inhibits ER stress and apoptosis induced by thapsigargin, a sarco/ER Ca2+-ATPase inhibitor, in β-cells of a rat insulinoma cell line, INS1e. We further explored effects on the Hh signaling receptor Smoothened (SMO) with pharmacologic agonists and inhibitors. Interference with sterol synthesis or efflux enhanced β-cell apoptosis and abrogated the anti-apoptotic activity of HDL. During ER stress, HDL facilitated the efflux of specific oxysterols, including 24-hydroxycholesterol (OHC). Supplementation of reconstituted HDL with 24-OHC enhanced and, in cells lacking ABCG1 or the 24-OHC synthesizing enzyme CYP46A1, restored the protective activity of HDL. Inhibition of SMO countered the beneficial effects of HDL and also LDL, and SMO agonists decreased β-cell apoptosis in the absence of ABCG1 or CYP46A1. The translocation of the SMO-activated transcription factor glioma-associated oncogene GLI-1 was inhibited by ER stress but restored by both HDL and 24-OHC. In conclusion, the protective effect of HDL to counter ER stress and β-cell death involves the transport, generation, and mobilization of oxysterols for activation of the Hh signaling receptor SMO

scholarly journals Bio-produced Propionic Acid: A Review

2017 ◽  
Vol 62 (1) ◽  
pp. 57-67 ◽  
Author(s):  
Aladár Vidra ◽  
Áron Németh
Keyword(s):  
Propionic Acid ◽  
Strain Improvement ◽  
Product Yield ◽  
Downstream Processing ◽  
Product Inhibition ◽  
Product Recovery ◽  
Acid Fermentation ◽  
Fermentation Processes ◽  
Propionic Acid Production ◽  
Downstream Area

Propionic acid is a platform chemical, antifungal agent and important chemical intermediate. Current industrial production of propionic acid is mainly through petrochemical processes because the conventional method of the propionic acid fermentation is uneconomical due to low product yield, productivity and product concentration caused by end-product inhibition. The coproduction of acetic and succinic acids in the propionic acid fermentation processes also makes downstream processing more complicated and costly. To the best of our knowledge there are several and recent reviews in the available literature on propionic acid fermentation processes and strain improvement techniques, but only a few on product recovery and purification, i.e. downstreaming. However, to realize a biorefinery, where propionic acid is a key intermediate, complex discussion of up-, and downstreaming is required. Therefore in this review a short overview of the whole bio-based propionic acid production process is presented including recent results of both upstream and downstream area. Thus the biosynthetic pathways, the significant results of native and recombinant producer strains as well as product recovery are discussed.

scholarly journals Amino Acid Substitution in Trichophyton rubrum Squalene Epoxidase Associated with Resistance to Terbinafine

2005 ◽  
Vol 49 (7) ◽  
pp. 2840-2844 ◽  
Author(s):  
Colin S. Osborne ◽  
Ingrid Leitner ◽  
Bertrand Favre ◽  
Neil S. Ryder
Keyword(s):  
Amino Acid ◽  
Amino Acid Substitution ◽  
Trichophyton Rubrum ◽  
Clinical Isolates ◽  
Single Amino Acid ◽  
Squalene Epoxidase ◽  
Reading Frame ◽  
Resistant Phenotype ◽  
Resistant Strains ◽  
Type Sequence

ABSTRACT There has only been one clinically confirmed case of terbinafine resistance in dermatophytes, where six sequential Trichophyton rubrum isolates from the same patient were found to be resistant to terbinafine and cross-resistant to other squalene epoxidase (SE) inhibitors. Microsomal SE activity from these resistant isolates was insensitive to terbinafine, suggesting a target-based mechanism of resistance (B. Favre, M. Ghannoum, and N. S. Ryder, Med. Mycol. 42:525-529, 2004). In this study, we have characterized at the molecular level the cause of the resistant phenotype of these clinical isolates. Cloning and sequencing of the SE gene and cDNA from T. rubrum revealed the presence of an intron in the gene and an open reading frame encoding a protein of 489 residues, with an equivalent similarity (57%) to both yeast and mammalian SEs. The nucleotide sequences of SE from two terbinafine-susceptible strains were identical whereas those of terbinafine-resistant strains, serially isolated from the same patient, each contained the same single missense introducing the amino acid substitution L393F. Introduction of the corresponding substitution in the Candida albicans SE gene (L398F) and expression of this gene in Saccharomyces cerevisiae conferred a resistant phenotype to the transformants when compared to those expressing the wild-type sequence. Terbinafine resistance in these T. rubrum clinical isolates appears to be due to a single amino acid substitution in SE.

scholarly journals Astaxanthin and other Nutrients from Haematococcus pluvialis—Multifunctional Applications

Marine Drugs ◽  
2020 ◽  
Vol 18 (9) ◽  
pp. 459 ◽  
Author(s):  
Malwina Mularczyk ◽  
Izabela Michalak ◽  
Krzysztof Marycz
Keyword(s):  
Haematococcus Pluvialis ◽  
Health And Safety ◽  
Anticancer Activities ◽  
Valuable Component ◽  
High Biological Activity ◽  
Natural Origin ◽  
Beneficial Effects ◽  
Animal Diseases ◽  
Green Microalga ◽  
Human And Animal Diseases

Bioactive compounds of natural origin are gaining increasing popularity. High biological activity and bioavailability, beneficial effects on health and safety of use are some of their most desirable features. Low production and processing costs render them even more attractive. Microorganisms have been used in the food, medicinal, cosmetic and energy industries for years. Among them, microalgae have proved to be an invaluable source of beneficial compounds. Haematococcus pluvialis is known as the richest source of natural carotenoid called astaxanthin. In this paper, we focus on the cultivation methods of this green microalga, its chemical composition, extraction of astaxanthin and analysis of its antioxidant, anti-inflammatory, anti–diabetic and anticancer activities. H. pluvialis, as well as astaxanthin can be used not only for the treatment of human and animal diseases, but also as a valuable component of diet and feed.

scholarly journals Spread of Terbinafine-Resistant Trichophyton mentagrophytes Type VIII (India) in Germany–“The Tip of the Iceberg?”

2020 ◽  
Vol 6 (4) ◽  
pp. 207
Author(s):  
Pietro Nenoff ◽  
Shyam B. Verma ◽  
Andreas Ebert ◽  
Anke Süß ◽  
Eleni Fischer ◽  
...  
Keyword(s):  
Amino Acid ◽  
Amino Acid Substitution ◽  
Indian Subcontinent ◽  
Resistance Testing ◽  
Public Health Issue ◽  
Squalene Epoxidase ◽  
Amino Acid Substitutions ◽  
Type Viii ◽  
Resistant Strains

Chronic recalcitrant dermatophytoses, due to Trichophyton (T.) mentagrophytes Type VIII are on the rise in India and are noteworthy for their predominance. It would not be wrong to assume that travel and migration would be responsible for the spread of T. mentagrophytes Type VIII from India, with many strains resistant to terbinafine, to other parts of the world. From September 2016 until March 2020, a total of 29 strains of T. mentagrophytes Type VIII (India) were isolated. All patients were residents of Germany: 12 females, 15 males and the gender of the remaining two was not assignable. Patients originated from India (11), Pakistan (two), Bangladesh (one), Iraq (two), Bahrain (one), Libya (one) and other unspecified countries (10). At least two patients were German-born residents. Most samples (21) were collected in 2019 and 2020. All 29 T. mentagrophytes isolates were sequenced (internal transcribed spacer (ITS) and translation elongation factor 1-α gene (TEF1-α)). All were identified as genotype VIII (India) of T. mentagrophytes. In vitro resistance testing revealed 13/29 strains (45%) to be terbinafine-resistant with minimum inhibitory concentration (MIC) breakpoints ≥0.2 µg/mL. The remaining 16 strains (55%) were terbinafine-sensitive. Point mutation analysis revealed that 10/13 resistant strains exhibited Phe397Leu amino acid substitution of squalene epoxidase (SQLE), indicative for in vitro resistance to terbinafine. Two resistant strains showed combined Phe397Leu and Ala448Thr amino acid substitutions, and one strain a single Leu393Phe amino acid substitution. Out of 16 terbinafine-sensitive strains, in eight Ala448Thr, and in one Ala448Thr +, new Val444 Ile amino acid substitutions were detected. Resistance to both itraconazole and voriconazole was observed in three out of 13 analyzed strains. Treatment included topical ciclopirox olamine plus topical miconazole or sertaconazole. Oral itraconazole 200 mg twice daily for four to eight weeks was found to be adequate. Terbinafine-resistant T. mentagrophytes Type VIII are being increasingly isolated. In Germany, transmission of T. mentagrophytes Type VIII from the Indian subcontinent to Europe should be viewed as a significant public health issue.

Sign in / Sign up

Export Citation Format

Share Document