• Microbiology and Biotechnology Letters
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• v.13 no.4
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• pp.377-382
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• 1985

As an essential previous step towards the development of cell fusion to breed a new brewing yearst strain, several factors predicted to affect the protoplast formation of S. cerevisiae, C. tropicalis and E. fibuligera were investigated in order to obtain the protoplasts in high yields. The optimum pH and temperature for the protoplas formation were 7.5 and 35$^{\circ}C$, respectively. Pretreatment of the yeast cells with 2-mercaptoethanol stimulated the protoplast formation and 50mM of the reagent was found as effective. Among several osmotic stabilizers tested for their effect on protoplas formation, 0.6M KCI was comparatively favorable.

• Food Science and Preservation
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• v.23 no.7
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• pp.1042-1049
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• 2016

This study was conducted to investigate and compare the characteristics of acetic acid fermentation in detoxified Rhus verniciflua vinegar (DRV) produced by different yeast strains. The DRVs were prepared by static acetic acid fermentation using six different yeast strains (Saccharomyces cerevisiae Fermivin, Pichia kudriavzerii N77-4, Hanseniaspora pountiae HP1-2, Candida tropicalis Y447, Wickerhamomyces anomalus N43-8, and Pichia kluyveri Frootzen). Alcohol content of the S. cerevisiae Fermivin fermented DRV was highest 16.07%. Among the yeast strain DRVs, there were significant differences in alcohol content, but all alcohol levels were 11%. Moreover, there were differences in pH and titratable acidity of the DRVs. The organic acid content of the DRVs ranged from 35.88 to 55.49 mg/mL and there were significant differences among the yeast strain DRVs. Essential free amino acids, particularly glutamic acid, alanine, leucine and valine, were detected in each of the 6 DRVs. Electronic nose analysis revealed that three different volatile chemical patterns were present in the 6 DRVs. The results indicate that yeast strains with different characteristics can produce vinegars with different characteristics.

• KSBB Journal
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• v.28 no.5
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• pp.315-318
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• 2013

Ethanol fermentations were performed using separate hydrolysis and fermentation (SHF) processes with monosaccharides from pretreated seaweed, Eucheuma spinosum as the biomass. The pretreatment was carried out with 11% (w/v) seaweed slurry and 150 mM $H_2SO_4$ at $121^{\circ}C$ for 40 min. Enzyme hydrolysis after $H_2SO_4$ pretreatment was performed with Celluclast 1.5 L at $45^{\circ}C$ for 24 h. Five % active charcoal were added to hydrolysate to removed 5-hydroxy methylfurfural. Ethanol fermentation with 11% (w/v) seaweed hydrolysate was performed for 72~96 h using Kluyvermyces marxianus, Pichia stipits, Saccharomyces cervisiae and Candida tropicalis. Ethanol concentration was reached to 18 g/L by K. marxianus, 16 g/L by P. stipitis, 15 g/L by S. cerevisiae and 10 g/L by C. tropicalis, respectively. The ethanol yield from total monosugar was obtained 0.50 and ethanol productivity was obtained 0.38 g/L/h by K. marxianus.

• Mycobiology
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• v.48 no.2
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• pp.122-132
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• 2020

Citric acid is a commercially valuable organic acid widely used in food, pharmaceutical, and beverage industries. In this study, 260 yeast strains were isolated from soil, bread, juices, and fruits wastes and preliminarily screened using bromocresol green agar plates for their ability to produce organic acids. Overall, 251 yeast isolates showed positive results, with yellow halos surrounding the colonies. Citric acid production by 20 promising isolates was evaluated using both free and immobilized cell techniques. Results showed that citric acid production by immobilized cells (30-40 g/L) was greater than that of freely suspended cells (8-19 g/L). Of the 20 isolates, two (KKU-L42 and KKU-L53) were selected for further analysis based on their citric acid production levels. Immobilized KKU-L42 cells had a higher citric acid production rate (62.5%), while immobilized KKU-L53 cells showed an ~52.2% increase in citric acid production compared with free cells. The two isolates were accurately identified by amplification and sequence analysis of the 26S rRNA gene D1/D2 domain, with GenBank-based sequence comparison confirming that isolates KKU-L42 and KKU-L53 were Candida tropicalis and Pichia kluyveri, respectively. Several factors, including fermentation period, pH, temperature, and carbon and nitrogen source, were optimized for enhanced production of citric acid by both isolates. Maximum production was achieved at fermentation period of 5 days at pH 5.0 with glucose as a carbon source by both isolates. The optimum incubation temperature for citric acid production by C. tropicalis was 32 ℃, with NH₄Cl the best nitrogen source, while maximum citric acid by P. kluyveri was observed at 27 ℃ with (NH₄)₂ SO₄ as the nitrogen source. Citric acid production was maintained for about four repeated batches over a period of 20 days. Our results suggest that apple and banana wastes are potential sources of novel yeast strains; C. tropicalis and P. kluyveri which could be used for commercial citric acid production.

• Korean Journal of Microbiology
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• v.9 no.1
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• pp.32-38
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• 1971

In solid culture of Endomycopsis fibuliger No.55, Eudomuopsis javanensis No.112 and Candida tropicalis No.340, the conditions of enzyme (protease, anylase and cellulase) production and the influence of addition of $(NH_4)_2;SO_4$ were examined, and the results obtained were as follows. 10 Wheat bran medium is found to be the best on the enzyme production in case of simple material. The optimum conditions ; are water content added 100 to 120%, temperature 25 to $80^{\circ}C$ and incubation times 2 to 3 days. 2) The cellulase production was scarely produced in the case of Endomyopsis fibuliger No.55, as well as, the amylase production was scarely producted in the case of Endomycopsis javanensis No.112 and Candida tropicalis No.340. 3) The enzyme production was remarkably increased when 5% of$(NH_4)_2;SO_4$ as inorganic nitrogen sources was admixed to wheat bran. 4) When 5% of $(NH_4)_2;SO_4$ was admixed to medium, the ratio of protein increase was 10.2 to 17.7% in wheat bran medium and 10.6 to 17.9% in sweet potato cake medium.

• Journal of Microbiology and Biotechnology
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• v.26 no.12
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• pp.2206-2213
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• 2016

Recently, several studies have revealed that commercial microbial identification systems do not accurately identify the uncommon causative species of candidiasis, including Candida famata, Meyerozyma guilliermondii, and C. auris. We investigated the accuracy of species-level identification in a collection of clinical isolates previously identified as C. famata (N = 38), C. lusitaniae (N = 1 2), and M. guilliermondii (N = 5) by the Vitek 2 system. All 55 isolates were re-analyzed by the Phoenix system (Becton Dickinson Diagnostics), two matrix-assisted laser desorption ionization-time of flight mass spectrometry analyzers (a Vitek MS and a Bruker Biotyper), and by sequencing of internal transcribed spacer (ITS) regions or 26S rRNA gene D1/D2 domains. Among 38 isolates previously identified as C. famata by the Vitek 2 system, the majority (27/38 isolates, 71.1%) were identified as C. tropicalis (20 isolates) or C. albicans (7 isolates) by ITS sequencing, and none was identified as C. famata. Among 20 isolates that were identified as C. tropicalis, 17 (85%) were isolated from urine. The two isolates that were identified as C. auris by ITS sequencing originated from ear discharge. The Phoenix system did not accurately identify C. lusitaniae, C. krusei, or C. auris. The correct identification rate for 55 isolates was 92.7% (51/55 isolates) for the Vitek MS and 94.6% (52/55 isolates) for the Bruker Biotyper, as compared with results from ITS sequencing. These results suggest that C. famata is very rare in Korea, and that the possibility of misidentification should be noted when an uncommon Candida species is identified.

• ALGAE
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• v.33 no.4
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• pp.291-304
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• 2018

Lyngbya C. Agardh ex Gomont is a nonheterocytous cyanobacterial genus whose evolutionary history is still poorly known. The traditionally defined Lyngbya has been demonstrated to be polyphyletic, including at least five distinct clades, some of which have been proposed as new genera. Intraspecific diversity is also clearly underestimated in Lyngbya due to the lack of unique morphological characters to differentiate species. In this study, we describe the new genus Capillus T. A. Caires, C. L. Sant'Anna et J. M. C. Nunes from benthic marine environments, including two new Brazilian species (here described as C. salinus T. A. Caires, C. L. Sant'Anna et J. M. C. Nunes, and C. tropicalis T. A. Caires, C. L. Sant'Anna et J. M. C. Nunes), and two species yet to be described, one of them from India (Capillus sp. 2.1), and the other from United States of America, based on strain PCC 7419. Capillus species presented cross-wise diagonal fragmentation, assisted or not by necridic cells, which has not been previously mentioned for Lyngbya. Ultrastructural analyses showed that C. salinus and C. tropicalis have numerous gas vesicles, which are rarely described for benthic marine species. The new genus formed a well-supported clade, and the D1-D1' and Box B secondary structures of internal transcribed spacer also supported the proposal of its new species. These findings help to clarify the diversity of species in the Lyngbya complex and the taxonomy of the group, and highlight the need of further floristic surveys in tropical coastal environments, which remain poorly studied.

• KSBB Journal
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• v.28 no.5
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• pp.282-286
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• 2013

The seaweed, Gelidium amansii, was fermented to produce bioethanol. Optimal pretreatment condition was determined as 94 mM $H_2SO_4$ and 8% (w/v) seaweed slurry at $121^{\circ}C$ for 60 min. The mono sugars of 40.4 g/L with 67% of conversion from total carbohydrate of 60.6 g/L with 80 g dw/L G. amansii slurry were obtained by thermal acid hydrolysis pretreatment and enzymatic saccharification. G. amansii hydrolysate was used as the substrate for ethanol production by Kluyveromyces marxianus KCTC 7150 and Candida tropicalis KCTC 7212 using 5L fermentor. The ethanol productions by K. marxianus KCTC 7150 and C. tropicalis KCTC 7212 were 17.8 g/L with $Y_{EtOH}$ of 0.48 at 120 h and 19.3 g/L with $Y_{EtOH}$ of 0.50 at 120 h, respectively.

• KSBB Journal
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• v.17 no.1
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• pp.93-99
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• 2002

Two-stage fed-batch culture of Candide tropicalis that was designated primarily to cultivate the cell in the glucose medium (1st stage) and then produced the xylitol from xylose medium (2nd stage) was developed to improve a xylitol yield and productivity. In the growth stage, glucose was automatically supplied to the fermentor by pH-stat mode when the pH was up 5.7, When a feeding medium was added in order to reach the glucose and yeast extract concentrations up to 100 and 40 g/L, respectively, a high cell concentration and a relatively low ethanol concentration were obtained in 18.5 h culture. In the production stage, initial xylose concentration of 150 g/L was the most favorable for obtaining the final xylitol concentration and productivity. The addition of mineral salts was also enhanced a xylitol production. But the aeration rate was not significantly affected a xylitol production. When the addition of 16 g yeast extract and 232.5 g xylose powder at the production stage was used, xylitol yield and productivity were significantly increased. With these conditions, xylitol concentration, yield and productivity of 108.9 g/L, 74%) and 3.3 g/L·h, respectively, were obtained in a final volume of 1.58 L. The further addition of 16 g yeast extract and 232.5 g xylose powder increased the working volume partly (1.67 L) and resulted in a relatively high xylitol concentration, yield and productivity of 193 g/L, 70% and 3.6 g/L·h, respectively.

• Korean Journal of Food Science and Technology
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• v.2 no.2
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• pp.61-67
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• 1970

The growth characteristics of Candida tropicalis KIST 359, isolated from soil samples collected at an oil depot in Korea, have been studied by cultivating batches under varying conditions. The conclusions of the study were: 1. The yeast easily assimilates hydrocarbons in a range of $C_{14}-C_{17}$, and the optimum cultivation temperature and pH are $30^{\circ}C$ and 5.5, respectively. 2. Using this strain of micro-organism, gas oil gives a higher cell yield than kerosine and with gas oil except urea all other nitrogen sources $(NH_4NO_3,\;NH_4Cl,\;(NH_4)_2SO_4\;and\;(NH_4)_2HPO_4)$ similarly support a satisfactory growth of the yeast. 3. The highest yield is obtained with a gas oil level of 10%(v/v), and concentrations of nitrogen source and $MgSO_4{\cdot}7H_2O$ of 0.5 and 0.05%(w/v), respectively. 4. The protein content of dried yeast cells is 59.8%. Its amino acid composition can be compared well with that of FAO provisional patterns, but with a low methionine and a high lysine content.