• KSBB Journal
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• v.17 no.3
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• pp.290-294
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• 2002

The present work describes the improvement of an erythritol-producing strain to lower the formation of glycerol, which is a characteristic by-product of the strain and could cause difficulties in the recovery and purification of the final product. The yeast-like fungi Moniliella suaveolens var. nigra, isolated previously in the same laboratory from beehives, was mutated by exposing it to a 4 g/L NTG solution. From a total of 2000 mutated strains, Em6j30-14 was selected as the one having the most desirable properties. Cultivating the strain for seven days in 300 mL flasks containing 30 mL of a 400 g/L glucose medium resulted in an erythritol yield of 43%. The glycerol yield was 5%, which is a value 50% lower as compared with the wild type. However, attempts to reproduce the above results in a 5L-fermenter failed, resulting in a similar erythritol concentration but a much higher formation of glycerol. Possible reasons for such a different behaviour could be oxygen limitation or the aggregation of cells, but the exact mechanism could not yet be identified. Foam formation, which is another major problem in large-scale fermentation, tended to be much lower for the mutant strain.

• Journal of Life Science
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• v.11 no.2
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• pp.133-137
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• 2001

The molecular taxonomic relationship of nine species in the genus Moniliella Stolk & Dakin and Trichosporonoides Haskins & Spencer and six species of other yea나-like fungi was examined by sequencing analysis of large subunit rDNA D1/D2 variable domain. The fifteeen species fell into two major groups corresponding with their genetic relationships. The nine species of the genus Moniliella and Trichosporonoides were placed at the same cluster. similarity values based on the D1/D2 domain sequences were 45.4-100% among species of genus Moniliella, 45.2-84.4% among genus Trichosporonoides species, and 45.6-90.1% among species of genus Moniliella and Trichosporonoides. Identical sequence similarity was observed between M. suaveolens var. nigra and M. suaveolens. A colse relationship of M. mellis. and M. acetoabutens is observed. The result of this study provided and insight into the genetic origins of genus Moniliella and Trichosporonoides species as well as their genetic relationships. Genus Moniliella and Trichosporonoides are closely related to each other based on sequence analysis of the large subunit rDNA D1/D2 region and we suggest combination of the genus Moniliella and Trichosporonoides to single genus.

• KSBB Journal
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• v.13 no.3
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• pp.331-335
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• 1998

Erythritol is a four-carbon sugar alcohol with a low calorific value and non-cariogenicity. Erythritol is a new functional sweetener which can be used as sugar alternative. Erytheitol dose not cause discomfort such as diarrhoea and flatulence upon ingestion. The purpose of this study is to develope a novel process of erythritol economically in a large scale. To obtain a high erythritol producer, we have screened 3500 colonies from molasses, honey and honey combs. We have selected 40 erythritol-producing microorganisms, one of which yields 140g/L erythritol in 40% glucose medium. We have tested this strain in 5L fermentor to examine the fermentation characteristics. Results of fermentation show that the erythritol production was about 1.4g/L$.$hr in 400g/L glucose media with a 42% conversion. Further improvements require mutation for a higher producer, process optimization to reduce glycerol, and suppression of excessive foaming.

• KSBB Journal
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• v.14 no.5
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• pp.628-632
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• 1999

Optimization of the medium and fermentation conditions for erythritol production has been studied. We have found that the optimal carbon source was glucose at the concentration of 400 g/L. The optimal temperature was 3$0^{\circ}C$ with excessive aeration. Improved erythritol productivity was achieved by reducing the yeast extract from 5 g/L to 3g/L while adding 2.7 g/L urea, 1.79g/L $K_2HPO_4, and 0.18g/L MgSO$_4$. 7$H_2O. The erythritol productivity increased from 0.747 g/L/h to 1.071 g/L/h and the yield increased from 31.4% to 45.2%. The byproduct glycerol was reduced from 96.6g/L to 45.7g/L as well. We have performed 5L fermentation with and without the pH control. The erythritol productivity with the pH control was about 30% lower than that without pH control. Excessive foaming of 5L fermentation has been observed during fermentation.