The extremophile red alga
Galdieria sulphuraria
was successfully grown immobilized in a twin-layer porous substrate bioreactor (TL-PSBR). A maximal biomass growth rate of 10 g dry weight m
−2
day
−1
...was measured at a photon fluence rate of 200 μmol photons m
−2
s
−1
with addition of 1% CO
2
and a temperature of 34 °C. Under these conditions, a maximal biomass value of 232 g m
−2
was attained after 33 days of growth. Phycobilin productivity, however, was highest at a lower photon fluence rate of 100 μmol photons m
−2
s
−1
and reached a phycobilin value of 14 g m
−2
, a phycobilin content in the biomass of 63 mg g
−1
and a phycobilin growth rate of 0.28 g m
−2
day
−1
for phycocyanin and 0.23 g m
−2
day
−1
for allophycocyanin. Addition of CO
2
was essential to enhance growth and phycobilin production in
G. sulphuraria
and further optimization of the cultivation process in the TL-PSBR appears possible using a multi-phase approach, higher growth temperatures and optimization of nutrient supply. It is concluded that autotrophic cultivation of
G. sulphuraria
in a TL-PSBR is an attractive alternative to suspension cultivation for phycobilin production and applications in bioremediation.
Microalgae technology has been extensively studied during the last two decades. Thousands of species were isolated, and few are currently used in the market for multiple purposes. The current ...comprehensive review focuses on a promising species named
Neochloris oleoabundans
. It encompasses a historical overview of the species followed by a detailed description of its taxonomy, ecophysiology and morphology. Furthermore, a thorough screening is conducted to outline the production conditions employed to grow the microalga. In addition, multiple cell disruption and fractionation methods previously applied on
N. oleoabundans
are described and discussed together with the value chain creation after applying all the unit operations.
Polyphenols constitute one of the most common groups of substances in plants. Polyphenolic compounds have been reported to have a wide range of biological activities, many of which are related to ...their conventional antioxidant action; however, increasing scientific knowledge has highlighted their potential activity in preventing oral disease, including the prevention of tooth decay. The aim of this review is to show the emerging findings on the anti-cariogenic properties of polyphenols, which have been obtained from several in vitro studies investigating the effects of these bioactive molecules against Streptococcus mutans, as well as in vivo studies. The analysis of the literature supports the anti-bacterial role of polyphenols on cariogenic streptococci, suggesting (1) a direct effect against S. mutans; (2) an interaction with microbial membrane proteins inhibiting the adherence of bacterial cells to the tooth surface; and (3) the inhibition of glucosyl transferase and amylase. However, more studies, particularly in vivo and in situ, are necessary to establish conclusive evidence for the effectiveness and the clinical applications of these compounds in the prevention of dental caries. It is essential to better determine the nature and distribution of these compounds in our diet and to identify which of the hundreds of existing polyphenols are likely to provide the greatest effects.
Despite their large number and diversity, microalgae from only four genera are currently cultivated at large-scale. Three of those share common characteristics: they are cultivated mainly ...autotrophically and are extremophiles or tolerate "extreme conditions." Extreme growth conditions aid in preventing contamination and predation of microalgae, therefore facilitating outdoor cultivation. In search for new extremophilic algae suitable for large-scale production, we investigated six microalgal strains able to grow at pH below 3 and belonging to four genera;
ACUF158,
SAG 2045, and
ACUF238,
ACUF035 and
ACUF064 and ACUF074. All strains were cultivated autotrophically at light intensity of 100 and 300 μmol m
s
and pH between 1.9 and 2.9. The autotrophic biomass productivities were compared with one of the most productive microalgae,
SAG 211-8K, grown at pH 6.8. The acid tolerant strains have their autotrophic biomass productivities reported for the first time. Mixotrophic and heterotrophic properties were investigated when possible. Five of the tested strains displayed autotrophic biomass productivities 10-39% lower than
but comparable with other commercially relevant neutrophilic microalgae, indicating the potential of these microalgae for autotrophic biomass production under acidic growth conditions. Two acid tolerant species,
and
were able to grow mixotrophically with glucose.
and the two Galdieria strains were also cultivated heterotrophically with glucose at various temperatures.
failed to grow at 37°C, while
ACUF64 showed a temperature optimum of 37°C and
ACUF74 of 42°C. For each strain, the biomass yield on glucose decreased when cultivated above their optimal temperature. The possible biotechnological applications of our findings will be addressed.
Stevia rebaudiana Bertoni is a small perennial shrub of the Asteraceae (Compositae) family that is native to South America, particularly Brazil and Paraguay, where it is known as "stevia" or "honey ...leaf" for its powerful sweetness. Several studies have suggested that in addition to their sweetness, steviosides and their related compounds, including rebaudioside A and isosteviol, may offer additional therapeutic benefits. These benefits include anti-hyperglycaemic, anti-hypertensive, anti-inflammatory, anti-tumor, anti-diarrheal, diuretic, and immunomodulatory actions. Additionally, critical analysis of the literature supports the anti-bacterial role of steviosides on oral bacteria flora. The aim of this review is to show the emerging results regarding the anti-cariogenic properties of S. rebaudiana Bertoni. Data shown in the present paper provide evidence that stevioside extracts from S. rebaudiana are not cariogenic. Future research should be focused on in vivo studies to evaluate the effects on dental caries of regular consumption of S. rebaudiana extract-based products.
In this work, we want to investigate the impact of different substrates and different environmental condition on the biofilm communities growing on plaster, marble, and mortar substrates inside the ...Herculaneum Suburban Baths. To do so, we measured environmental conditions and sampled biofilm communities along the walls of the baths and used culture-dependent and -independent molecular techniques (DGGE) to identify the species at each sampling sites. We used the species pool to infer structure and richness of communities within each site in each substrate, and confocal light scanning microscopy to assess the three-dimensional structure of the sampled biofilms. To gather further insights, we built a meta-community network and used its local realizations to analyze co-occurrence patterns of species. We found that light is a limiting factor in the baths environment, that moving along sites equals moving along an irradiation gradient, and that such gradient shapes the community structure, de facto separating a dark community, rich in Bacteria, Fungi and cyanobacteria, from two dim communities, rich in Chlorophyta. Almost all sites are dominated by photoautotrophs, with Fungi and Bacteria relegated to the role of rare species., and structural properties of biofilms are not consistent within the same substrate. We conclude that the Herculaneum suburban baths are an environment-shaped community, where one dark community (plaster) and one dim community (mortar) provides species to a "midway" community (marble).
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
In this study, a strain of
UTEX 1444 was cultivated in six different concentrations of iron (III). Cultures were extracted with organic solvents and analyzed using our dereplication strategy, based ...on the combined use of high-resolution tandem mass spectrometry and molecular networking. The analysis showed the presence of the siderophores' family, named synechobactins, only in the zero iron (III) treatment culture. Seven unknown synechobactin variants were present in the extract, and their structures have been determined by a careful HRMS/MS analysis. This study unveils the capability of
UTEX 1444 to produce a large array of siderophores and may be a suitable model organism for a sustainable scale-up exploitation of such bioactive molecules, for the bioremediation of contaminated ecosystems, as well as in drug discovery.
The mutualistic interactions between the oleaginous yeast Lipomyces starkeyi and the green microalga Chloroidium saccharophilum in mixed cultures were investigated to exploit possible synergistic ...effects. In fact, microalga could act as an oxygen generator for the yeast, while the yeast could provide carbon dioxide to microalga. The behavior of the two microorganisms alone and in mixed culture was studied in two synthetic media (YEG and BBM + G) before moving on to a real model represented by the hydrolysate of Arundo donax, used as low-cost feedstock, and previously subjected to steam explosion and enzymatic hydrolysis. The overall lipid content and lipid productivity obtained in the mixed culture of YEG, BBM + G and for the hydrolysate of Arundo donax were equal to 0.064, 0.064 and 0.081 glipid·gbiomass−1 and 30.14, 35.56 and 37.22 mglipid·L−1·day−1, respectively. The mixed cultures, in all cases, proved to be the most performing compared to the individual ones. In addition, this study provided new input for the integration of Single Cell Oil (SCO) production with agro-industrial feedstock, and the fatty acid distribution mainly consisting of stearic (C18:0) and oleic acid (C18:1) allows promising applications in biofuels, cosmetics, food additives and other products of industrial interest.
Cyanobacteria contribute to the ecology of various marine environments, also for their symbioses, since some of them are common hosts of sponges and ascidians. They are also emerging as an important ...source of novel bioactive secondary metabolites in pharmacological (as anticancer drugs) and biotechnological applications. In the present work we isolated a cyanobacteria in a free-living state from leaves of the seagrass Posidonia oceanica leaves. This newly collected strain was then cultivated under two laboratory conditions, and then characterized by combining morphological observation and molecular studies based on 16S rRNA gene sequences analysis. The strain showed 99% pairwise sequence identity with Halomicronema metazoicum ITAC101, never isolated before as a free-living organisms, but firstly described as an endosymbiont of the Mediterranean marine spongae Petrosia ficiformis, under the form of a filamentous strain. Further studies will investigate the actual role of this cyanobacterium in the leaf stratum of P. oceanica leaves, given its demonstrated ability to influence the vitality and the life cycle of other organisms. In fact, its newly demonstrated free-living stage, described in this study, indicate that Phormidium-like cyanobacteria could play important roles in the ecology of benthic and planktonic communities.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
In the last decades, the interest in bioactive compounds derived from natural sources including bacteria, fungi, plants, and algae has significantly increased. It is well-known that aquatic or ...terrestrial organisms can produce, in special conditions, secondary metabolites with a wide range of biological properties, such as anticancer, antioxidant, anti-inflammatory, and antimicrobial activities. In this study, we focused on the extremophilic microalga
as a possible producer of bioactive compounds with antiviral activity. The algal culture was subjected to organic extraction with acetone. The cytotoxicity effect of the extract was evaluated by the 2,5-diphenyl-2H-tetrazolium bromide (MTT) assay. The antiviral activity was assessed through a plaque assay against herpesviruses and coronaviruses as enveloped viruses and poliovirus as a naked one. The monolayer was treated with different concentrations of extract, ranging from 1 µg/mL to 200 µg/mL, and infected with viruses. The algal extract displayed strong antiviral activity at non-toxic concentrations against all tested enveloped viruses, in particular in the virus pre-treatment against HSV-2 and HCoV-229E, with IC
values of 1.7 µg/mL and IC
of 1.8 µg/mL, respectively. However, no activity against the non-enveloped poliovirus has been detected. The inhibitory effect of the algal extract was confirmed by the quantitative RT-PCR of viral genes. Preliminary chemical profiling of the extract was performed using ultra-high-performance liquid chromatography coupled to high-resolution mass spectrometry (UHPLC-HRMS), revealing the enrichment in primary fatty acid amides (PFAA), such as oleamide, palmitamide, and pheophorbide A. These promising results pave the way for the further purification of the mixture to explore its potential role as an antiviral agent.
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