• Korean Journal of Microbiology
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• v.45 no.4
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• pp.324-331
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• 2009

MK1 strain, an obligate aerobic heterotrophic bacterium isolated from the rotten tissue of Neungee mushroom (Sarcodon aspratus), produces a copious amount of exopolysaccharide (EPS), which could evoke macrophage activation. Investigations on optimal culture conditions of MK1 and physical properties of MK1 EPS were made. Glucose, galactose, fructose, and sucrose supported well growth of MK1, but potato starch and dextrin did not. However, lactose seemed to be a less favorable carbon source. Optimal growth of MK1 was obtained at pH 7.0, $30^{\circ}C$, and 200 rpm with 2% glucose, and 0.2~0.05% $(NH_4)_2SO_4$. $EPS_{opt}$ obtained from an optimal growth condition constituted of carbon (37.1%), nitrogen (2.2%), oxygen (49.3%), and hydrogen (6.4%), but no sulfur. Paper chrogromatogram of the acid-hydrolysate of $EPS_{opt}$ suggested that MK1 EPS seemed to be hetropolysaccharide composed of a few number of monosaccharides including amino- and acidic-sugars. Its molecular mass determined by SDS-polyacrylamide gel electrophoresis varied from 14.8 to 47.9 kDa. Physical properties of $EPS_{glu}$ obtained from cell grown in glucose medium, such as relative viscosity ($_{rel}$) and crystalline morphology were rather affected by pH of the growth medium. Relative viscosity ($_{rel}$) of exopolysaccaride (0.1 g/ml) harvested from cells grown at medium pH ranging from 6.0 and 7.5 was 1.23 and 1.39, respectively. The freeze-dried exopolysaccharide obtained at low pH (6.0 and 6.5) was fine crystaloid and water-soluble, whereas those obtained at high pH (7.0 and 7.5) was rather gluey and less water-soluble.

• Microbiology and Biotechnology Letters
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• v.37 no.1
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• pp.33-41
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• 2009

The crushed fruiting body of Alaskan Porodaedalea pini (Brot.) Murrill (syn. Phellinus pini) was extracted in boiling water for 4 h with the yield of 20.5% in dry mass. This hot-water extract showed significant antiviral activity by inhibiting the plaque formation in HeLa cells by coxackievirus B3 (CVB3) and also showed highest inhibitory effect against neuraminidase activity among water extracts of various mushrooms. From the water extract, the ethanol precipitate (EP) and supernatant fraction (ES) were obtained through 75% ethanol precipitation with the yield of 43.3% and 28.3% in dry mass, respectively. Whereas ES did not show any detectable level of antiviral activity, EP showed significant dose-dependent inhibition of plaque formation by CVB3 in HeLa cells with an $EC_{50}$ (50% effective concentration) of 0.45 mg/mL. The cytotoxicity on HeLa cells by EP was relatively low with the $CC_{50}$ (50% cytotoxic concentration) of 2.25 mg/mL. EP also effectively inhibited neuraminidase activity in a dose-dependent manner showing up to 75% inhibition at 1.7 mg/mL. These results suggest that the hot-water extract and its EP of P. pini fruiting body can be a candidate for the development of a potent broad-range antiviral agent against influenza virus(Flu) as well as CVB3. The major active component of EP was shown to be a heteropolysaccharide-protein complex containing glucose as the main sugar residue with mole percentage of 79.8% and other sugars like galactose (19.2%), xylose (17%), mannose (5.8%), and fucose (4.6%) and a small portion (12.7%, in mass) of protein.

• Microbiology and Biotechnology Letters
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• v.36 no.1
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• pp.61-66
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• 2008

The proteins in whey are separated and used as food additives. The remains (mainly lactose) are spray-dried to produce sweet whey powder, which is widely used as an additive for animal feed. Sweet whey powder is also used as a carbon source for the production of valuable products such as polysaccharides. Glucose, fructose, galactose, and sucrose as asupplemental carbon source were evaluated for the production of PS-7 from Azotobacter indicus var. myxogenes L3 grown on whey based MSM media. Productions of PS-7 with 2% (w/v) fructose and sucrose were 2.05 and 2.31g/L, respectively. The highest production of PS-7 was 2.82g/L when 2% (w/v) glucose was used as the carbon source. Galactose showed low production of PS-7 among the carbon sources tested. The effects of various carbon sources addition to whey based MSM medium showed that glucose could be the best candidate for the enhancement of PS-7 production using whey based MSM medium. To evaluate the effect of glucose addition to whey based media on PS-7 production, fermentations with whey and glucose mixture (whey 1, 2, 3%; whey 1% + glucose 1%, whey 1% + glucose 2% and glucose 2%, w/v) were carried out. Significant enhancement of PS-7 production with addition of 1% (w/v) and 2% (w/v) glucose in 1% (w/v) whey media was observed. The PS-7 concentration of 2% glucose added whey lactose based medium was higher than that of 1% glucose addition, however, the product yield $Y_{p/s}$ was higher in 1% glucose added whey lactose based MSM medium. Therefore, the optimal condition for the PS-7 production from the Azotobacter indicus var.myxogenes L3, was 1% glucose addition to 1% whey lactose MSM medium.