Molecular taxonomy of yeasts

Evaluation of antioxidant activity of brown macroalgae found in Lampung Bay, Indonesia and molecular identification using DNA barcode cox1 BLAST

BACKGROUND

The study on identifying of brown macroalgae species, particularly those on the southern coast of Lampung Bay-Indonesia, at the molecular level and their antioxidant activity has never been conducted, so we examined it as our purpose study.

METHOD AND RESULTS

The research uses DPPH free radical scavenging activity and molecular identification using DNA barcode cox1 BLAST. Fifteen samples of fresh brown macroalgae with five samples, respectively, were collected from Sebalang Beach, Kalianda and Pesawaran, South Lampung. The DNA was first purified, and then the gene product was amplified using specific primers, cox1F1 primer and cox1R1 primer. The DNA sequence was checked and traced using the Basic Local Alignment Search Tool (BLAST). The three most dominant species of brown macroalgae were identified, namely Sargassum plagiophyllum, Sargassum ilicifolium and Hormophysa cuneiformis. The base length obtained ranged from 1164 to 1212 bp, with a similarity percentage of 98.36% to 100%. The three types of brown macroalgae have the ability to scavenge DPPH free radicals. Ethanol solvent and extract fractions significantly influence the reduction of DPPH free radicals. The ethanolic extract fraction of S. ilicifolium exhibited the lowest EC50 value (64.17 ± 1.23 mg L-1) and has the strongest antioxidant activity, followed by H. cuneiformis (75.88 ± 0.34 mg L-1), and S. plagiophyllum (82.97 ± 1.30 mg L-1).

CONCLUSION

The difference in species of brown macroalgae had no significant effect on the EC50 activity, and all three had robust antioxidant activity because their concentrations ranged between 50 and 100 mg L-1.

The role of indigenous yeasts in traditional Irish cider fermentations

AIMS

To study the role of the indigenous yeast flora in traditional Irish cider fermentations.

METHODS AND RESULTS

Wallerstein laboratory nutrient agar supplemented with biotin, ferric ammonium citrate, calcium carbonate and ethanol was employed together with PCR-restriction fragment length polymorphism analysis of the region spanning the internal transcribed spacers (ITS1 and ITS2) and the 5.8S rRNA gene in the identification of indigenous yeasts at the species level, from traditional Irish cider fermentations. By combining the molecular approach and the presumptive media it was possible to distinguish between a large number of yeast species, and to track them within cider fermentations. The Irish cider fermentation process can be divided into three sequential phases based on the predominant yeast type present. Kloeckera/Hanseniaspora uvarum type yeasts predominate in the initial 'fruit yeast phase'. Thereafter Saccharomyces cerevisiae type yeast dominate in the 'fermentation phase', where the alcoholic fermentation takes place. Finally the 'maturation phase' which follows, is dominated by Dekkera and Brettanomyces type yeasts. H. uvarum type yeast were found to have originated from the fruit. Brettanomyces type yeast could be traced back to the press house, and also to the fruit. The press house was identified as having high levels of S. cerevisiae type yeast. A strong link was noted between the temperature profile of the cider fermentations, which ranged from 22 to 35 degrees C and the yeast strain population dynamics.

CONCLUSIONS

Many different indigenous yeast species were identified. The mycology of Irish cider fermentations appears to be very similar to that which has previously been reported in the wine industry.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study has allowed us to gain a better understanding of the role of indigenous yeast species in 'Natural' Irish cider fermentations.