Search

Seaweed contains a variety of bioactive compounds; the most abundant of them are polysaccharides, which have significant biological and chemical importance. Although algal polysaccharides, especially the sulfated polysaccharides, have great potential in the pharmaceutical, medical and cosmeceutical sectors, the large molecular size often limits their industrial applications. The current study aims to determine the bioactivities of degraded red algal polysaccharides by several in vitro experiments. The molecular weight was determined by size-exclusion chromatography (SEC), and the structure was confirmed by FTIR and NMR. In comparison to the original furcellaran, the furcellaran with lower molecular weight had higher OH scavenging activities. The reduction in molecular weight of the sulfated polysaccharides resulted in a significant decrease in anticoagulant activities. Tyrosinase inhibition improved 2.5 times for hydrolyzed furcellaran. The alamarBlue assay was used to determine the effects of different Mw of furcellaran, κ-carrageenan and ι-carrageenan on the cell viability of RAW264.7, HDF and HaCaT cell lines. It was found that hydrolyzed κ-carrageenan and ι-carrageenan enhanced cell proliferation and improved wound healing, whereas hydrolyzed furcellaran did not affect cell proliferation in any of the cell lines. Nitric oxide (NO) production decreased sequentially as the Mw of the polysaccharides decreased, which indicates that hydrolyzed κ-Carrageenan, ι-carrageenan and furcellaran have the potential to treat inflammatory disease. These findings suggested that the bioactivities of polysaccharides were highly dependent on their Mw, and the hydrolyzed carrageenans could be used in new drug development as well as cosmeceutical applications. [ABSTRACT FROM AUTHOR]

Background: With a preceding scrutiny of bacterial cellular responses against heat shock and oxidative stresses, current research further investigated such impact on yeast cell. Present study attempted to observe the influence of high temperature (44-46 °C) on the growth and budding pattern of Saccharomyces cerevisiae SUBSC01. Effect of elevated sugar concentrations as another stress stimulant was also observed. Cell growth was measured through the estimation of the optical density at 600 nm (OD600) and by the enumeration of colony forming units on the agar plates up to 450 min. Results: Subsequent transformation in the yeast morphology and the cellular arrangement were noticed. A delayed and lengthy lag phase was observed when yeast strain was grown at 30, 37, and 40 °C, while at 32.5 °C, optimal growth pattern was noticed. Cells were found to lose culturability completely at 46 °C whereby cells without the cytoplasmic contents were also observed under the light microscope. Thus the critical growth temperature was recorded as 45 °C which was the highest temperature at which S. cerevisiae SUBSC01 could grow. However, a complete growth retardation was observed at 45 °C with the high concentrations of dextrose (0.36 g/l) and sucrose (0.18 g/l). Notably, yeast budding was found at 44 and 45 °C up to 270 min of incubation, which was further noticed to be suppressed at 46 °C. Conclusions: Present study revealed that the optimal and the critical growth temperatures of S. cerevisiae SUBSC01 were 32.5 and 45 °C, respectively; and also projected on the inhibitory concentrations of sugars on yeast growth at that temperature. [ABSTRACT FROM AUTHOR]

Background: With a preceding scrutiny of bacterial cellular responses against heat shock and oxidative stresses, current research further investigated such impact on yeast cell. Present study attempted to observe the influence of high temperature (44–46 °C) on the growth and budding pattern of Saccharomyces cerevisiae SUBSC01. Effect of elevated sugar concentrations as another stress stimulant was also observed. Cell growth was measured through the estimation of the optical density at 600 nm (OD600) and by the enumeration of colony forming units on the agar plates up to 450 min. Results: Subsequent transformation in the yeast morphology and the cellular arrangement were noticed. A delayed and lengthy lag phase was observed when yeast strain was grown at 30, 37, and 40 °C, while at 32.5 °C, optimal growth pattern was noticed. Cells were found to lose culturability completely at 46 °C whereby cells without the cytoplasmic contents were also observed under the light microscope. Thus the critical growth temperature was recorded as 45 °C which was the highest temperature at which S. cerevisiae SUBSC01 could grow. However, a complete growth retardation was observed at 45 °C with the high concentrations of dextrose (0.36 g/l) and sucrose (0.18 g/l). Notably, yeast budding was found at 44 and 45 °C up to 270 min of incubation, which was further noticed to be suppressed at 46 °C. Conclusions: Present study revealed that the optimal and the critical growth temperatures of S. cerevisiae SUBSC01 were 32.5 and 45 °C, respectively; and also projected on the inhibitory concentrations of sugars on yeast growth at that temperature. [ABSTRACT FROM AUTHOR]

• P. pentosaceus , S. fibuligera, and S. cerevisiae were developed as sourdough bread starters. • The sourdough bread had antifungal activity against A. flavus in situ. • The isolated P. pentosaceus had antifungal activity against A. flavus. • The lactic and acetic acid concentration in sourdough bread were increased over 4.5 and 1.6-fold. • Fifteen volatile compounds were newly detected in sourdough bread by SPME-GC/MS. Six lactic acid bacteria (LAB) and four yeast strains were isolated from Pyeongchang spontaneous sourdough. In combination with the segregated Saccharomycopsis fibuligera and Saccharomyces cerevisiae , Pediococcus pentosaceus was employed for sourdough bread starters because of its antifungal action against Aspergillus flavus. The sourdough bread fermented with P. pentosaceus and S. cerevisiae displayed 56.4% ± 5.5% antifungal movement counter to A. flavus expansion at 96 h. The concentration of lactic and acetic acids in the sourdough bread was 4.5- and 1.6-folds above the control bread, respectively, contributing to the balanced sensory properties with a fermentation quotient (FQ) of 2.08–2.86. SPME- GC/MS newly distinguished twenty-two volatile compounds including six aldehydes, five alcohols, one phenol, three ketones, one acid, and six esters. The results suggest the P. pentosaceus and S. cerevisiae combination as promising sourdough starters for making enhanced quality bread free of preservatives. [ABSTRACT FROM AUTHOR]

The nonpathogenic yeast Saccharomyces boulardii (Sb) has beneficial effects on the human intestine, and thus has been prescribed as probiotics for the treatment of diarrhea and gastrointestinal diseases. This is the only commercialized yeast with the purpose of being used as human medicine. Currently, little is known about their multiple mechanisms of actions. The S. boulardii yeast strain is isolated and identified by using the BIOLOG TM microarray identification system and morphologically. To understand its functional roles, the present study investigates the ability of this yeast to tolerate different concentrations of bile salt up to 2.5%, cell hydrophobicity, antioxidants, autoaggregation activity, and simulated gastrointestinal digestion. The effect of temperatures (up to 50°C), pH (up to 8.0), and salinity (at best 7%) was also monitored on the growth and survival of the yeast cell. The physicochemical analyses revealed that S. boulardii could survive in stomach conditions at pH 2.5, temperature 37°C, and 2% bile salt. Antibiotic susceptibility of S. boulardii was carried out using commercial antibiotic discs. The antimicrobial activity of the isolated S. boulardii against bacterial pathogens related to diarrhea diseases was in-vitro determined by the Well Diffusion method. The biosafety assay findings also claimed S. boulardii could be a potential probiotic. The experimental findings suggest that the isolated S. boulardii possesses excellent probiotic capacities as a biotherapeutic agent for antidiarrheal and gastrointestinal disorders., (Copyright © 2020 Hossain, Afrin, Humayun, Ahmed and Saha.)