• Journal of Microbiology and Biotechnology
• /
• v.26 no.1
• /
• pp.110-119
• /
• 2016

High-solid anaerobic digestion of sewage sludge achieves highly efficient volatile solid reduction, and production of volatile fatty acid (VFA) and methane compared with conventional low-solid anaerobic digestion. In this study, the potential mechanisms of the better performance in high-solid anaerobic digestion of sewage sludge were investigated by using 454 high-throughput pyrosequencing and real-time PCR to analyze the microbial characteristics in sewage sludge fermentation reactors. The results obtained by 454 highthroughput pyrosequencing revealed that the phyla Chloroflexi, Bacteroidetes, and Firmicutes were the dominant functional microorganisms in high-solid and low-solid anaerobic systems. Meanwhile, the real-time PCR assays showed that high-solid anaerobic digestion significantly increased the number of total bacteria, which enhanced the hydrolysis and acidification of sewage sludge. Further study indicated that the number of total archaea (dominated by Methanosarcina) in a high-solid anaerobic fermentation reactor was also higher than that in a low-solid reactor, resulting in higher VFA consumption and methane production. Hence, the increased key bacteria and methanogenic archaea involved in sewage sludge hydrolysis, acidification, and methanogenesis resulted in the better performance of high-solid anaerobic sewage sludge fermentation.

• KSBB Journal
• /
• v.28 no.6
• /
• pp.400-407
• /
• 2013

The growth characteristics and production of color pigments by Monascus strains were investigated during liquid culture, and production of monacolin K in red mold rice was carried out by solid state fermentation. Four different Monascus ruber strains were cultured in potato dextrose yeast extract broth (PDYB) media at $25^{\circ}C$ for 15 days. The high producing strain for red pigment was not corresponded to the strain for yellow pigment. Production of red pigment was high in the strain causing the fast pH change in culture broth. Production of monacolin K in red mold rice by solid state fermentation was influenced by a combination of wet cell weight and spore density in inoculum by liquid culture. Most strains showed the high production of monacolin K in red mold rice, when submerged fermentation was carried out for 5 days as inoculum for solid state fermentation. These results suggest that submerged fermentation period of inoculum have an effect on the production of monacolin K in red mold rice by solid state fermentation, and monacolin K in red mold rice could be increased by controlling the condition of submerged fermentation for inoculum.

• Journal of Microbiology and Biotechnology
• /
• v.32 no.3
• /
• pp.317-323
• /
• 2022

Solid-state fermentation using hulled barley was carried out to produce enzymes and β-glucan. The one-factor-at-a-time experiments were carried out to determine the optimal composition of the basal medium. The modified synthetic medium composition in liquid-state fermentation was determined to be 70 g/l hulled barley, 0 g/l rice bran, 5 g/l soytone, and 6 g/l ascorbic acid. Optimal pretreatment conditions of hulled barley by solid-state fermentation were evaluated in terms of maximum production of fungal biomass, amylase, protease, and β-glucan, which were 1.26 mg/g, 31310.34 U/g, 2614.95 U/g, and 14.6% (w/w), respectively, at 60 min of pretreatment condition. Thus, the solid-state fermentation process was found to enhance the overall fermentation yields of hulled barley to produce high amounts of enzymes and β-glucan.

• Asian-Australasian Journal of Animal Sciences
• /
• v.21 no.11
• /
• pp.1635-1641
• /
• 2008

This study investigated the effects of solid-state fermentation of a compound pig feed on its microbial and nutritional characteristics as well as on pig performance and nutrient digestibility. A mixed culture containing Lactobacillus fermentum, Saccharomyces cerevisae and Bacillus subtilis was used for solid-state fermentation and solid-state fermented feed samples were collected on days 0, 1, 2, 3, 5, 7, 10, 15, 20 and 30 for microbial counts and chemical analysis. Lactic acid bacteria increased rapidly during the first three days of fermentation and then slowly declined until day 10 and, thereafter, the counts were maintained at about 6.7 log cfu/g for the duration of the fermentation period. Enterobacteria also increased during the first two days, and then fell below the detectable level of the analysis (3.0 log cfu/g). The pH of the fermentation substrate declined from 6.1 at the start of fermentation to 5.7 by day 30. The water-soluble protein content increased from 8.2 to 9.2% while the concentration of acetic acid increased from 16.6 to 51.3 mmol/kg over the 30-day fermentation. At the end of the 30-day fermentation, the solid-state fermented feed was used in a pig feeding trial to determine its effects on performance and nutrient digestibility in growing-finishing pigs. Twenty crossbred barrows ($14.11{\pm}0.77kg\;BW$) were allotted into two dietary treatments, which comprised a regular dry diet containing antibiotics and a solid-state fermented feed based diet, free of antibiotics. There was no difference due to diet on pig performance or nutrient digestibility. In conclusion, solid-state fermentation resulted in high counts of lactic acid bacteria and low counts of enterobacteria in the substrate. Moreover, feeding a diet containing solid-state fermented feed, free of antibiotics, can result in similar performance and nutrient digestibility in growing-finishing pigs to a regular diet with antibiotics.

• Journal of Microbiology and Biotechnology
• /
• v.18 no.7
• /
• pp.1257-1265
• /
• 2008

To lower the cost of ethanol distillation of fermentation broths, a high initial glucose concentration is desired. However, an increase in the substrate concentration typically reduces the ethanol yield because of insufficient mass and heat transfer. In addition, different operating temperatures are required to optimize the enzymatic hydrolysis (50$^{\circ}C$) and fermentation (30$^{\circ}C$). Thus, to overcome these incompatible temperatures, saccharification followed by fermentation (SFF) was employed with relatively high solid concentrations (10% to 20%) using a portion loading method. In this study, glucose and ethanol were produced from Solka Floc, which was first digested by enzymes at 50$^{\circ}C$ for 48 h, followed by fermentation. In this process, commercial enzymes were used in combination with a recombinant strain of Zymomonas mobilis (39679:pZB4L). The effects of the substrate concentration (10% to 20%, w/v) and reactor configuration were also investigated. In the first step, the enzyme reaction was achieved using 20 FPU/g cellulose at 50$^{\circ}C$ for 96 h. The fermentation was then performed at 30$^{\circ}C$ for 96 h. The enzymatic digestibility was 50.7%, 38.4%, and 29.4% after 96 h with a baffled Rushton impeller and initial solid concentration of 10%, 15%, and 20% (w/v), respectively, which was significantly higher than that obtained with a baffled marine impeller. The highest ethanol yield of 83.6%, 73.4%, and 21.8%, based on the theoretical amount of glucose, was obtained with a substrate concentration of 10%, 15%, and 20%, respectively, which also corresponded to 80.5%, 68.6%, and 19.1%, based on the theoretical amount of the cell biomass and soluble glucose present after 48 h of SFF.

• Mycobiology
• /
• v.34 no.3
• /
• pp.128-130
• /
• 2006

The solid waste of sago industry using cassava was fermented by Aspergillus niger, Aspergillus terreus and Rhizopus stolonifer in solid state fermentation. Cassava waste contained 52 per cent starch and 2.9 per cent protein by dry weight. The amylase activity was maintained at a high level and the highest amylase activity was observed on the $8^{th}$ day in R. stolonifer mediated fermentation. R. stolonifer was more efficient than Aspergillus niger and Aspergillus terreus in bioconverting cassava waste into fungal protein (90.24 mg/g) by saccharifying 70% starch and releasing 44.5% reducing sugars in eight days of solid state fermentation.

• Journal of Microbiology and Biotechnology
• /
• v.27 no.1
• /
• pp.1-8
• /
• 2017

The production of high-value chemicals from natural resources as an alternative for petroleum-based products is currently expanding in parallel with biorefinery. The use of lignocellulosic biomass as raw material is promising to achieve economic and environmental sustainability. Filamentous fungi, particularly Aspergillus species, are already used industrially to produce organic acid as well as many enzymes. The production of lignocellulose-degrading enzymes opens the possibility for direct fungal fermentation towards organic acids such as itaconic acid (IA) and fumaric acid (FA). These acids have wide-range applications and potentially addressable markets as platform chemicals. However, current technologies for the production of these compounds are mostly based on submerged fermentation. This work showed the capacity of two Aspergillus species (A. terreus and A. oryzae) to yield both acids by solid-state fermentation and simultaneous saccharification and fermentation. FA was optimally produced at by A. oryzae in simultaneous saccharification and fermentation (0.54 mg/g wheat bran). The yield of 0.11 mg IA/g biomass by A. oryzae is the highest reported in the literature for simultaneous solid-state fermentation without sugar supplements.

• Journal of The Korean Society of Grassland and Forage Science
• /
• v.32 no.4
• /
• pp.361-368
• /
• 2012

The present study was conducted to develop persimmon peel, a by-product of dried persimmon manufacturing, as a feed additive via lactic acid bacteria fermentation. Pediococcus pentosaceus, Lactobacillus plantarum, and three strains of Leuconostoc mesenteroides were used as a starter culture in the solid state fermentation of persimmon peel, and antioxidant activity and total polyphenol content were assessed. Leuconostoc mesenteroides KCTC 3100 showed high antioxidant activity (p<0.05), whereas Pediococcus pentosaceus showed high total polyphenol content (p<0.05). These two strains were thus selected as starter culture strains. Glucose, sucrose and molasses were used as variables for optimization and a total 15 experimental runs were produced according to Box-Behnken design. Regarding significant effects of variables, molasses showed linear and square effects on antioxidant activity of persimmon peel fermentation (p<0.05). In conclusion, optimum concentrations of glucose, sucrose, and molasses were determined to be 4.2, 3.9 and 5.3 g/L, respectively, using a response surface model. Antioxidant activity was also improved 2.5 fold after optimization.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.26 no.5
• /
• pp.794-799
• /
• 1997

The effective fermentation methods of Kimchi juice for utilization of outer layer of Chinese cabbage, an waste of Kimchi industry were studied. The Kimchi juice prepared with brining and grinding the waste of Chinese cabbage and addition of spices was fermented at $25^{\circ}C$. Addition of 5$^{\circ}C$15% fermented Kimchi juice of pH 5.4 at initial stage and pH 4.4 at middle state resulted in a significant increase in fermentation rate and solid content after 12 hours of fermentation. The combined method of enzymatic hydrolysis(0.1% viscozyme) of the brined and ground cabbage and addition of 2.0% NaCl, 1.0% sucrose and 10% fermented juice of pH 5.4 first and 4.4 during fermentation, respectively resulted in more rapid fermentation. The solid concentration was 5 times higher than control at maximum point and acidic and total flavor intensity were also significantly high.

• Journal of Microbiology and Biotechnology
• /
• v.20 no.4
• /
• pp.718-726
• /
• 2010

A selected fungal strain, for production of the raw-starchdigesting enzyme by solid-state fermentation, was improved by two repeated sequential exposures to ${\gamma}$-irradiation of $Co^{60}$, ultraviolet, and four repeated treatments with Nmethyl-N'-nitrosoguanidine. The mutant strain Aspergillus sp. XN15 was chosen after a rigorous screening process, with its production of the raw-starch-digesting enzyme being twice that of usual wild varieties cultured under preoptimized conditions and in an unsupplemented medium. After 17 successive subculturings, the enzyme production of the mutant was stable. Optimal conditions for the production of the enzyme by solid-state fermentation, using wheat bran as the substrate, were accomplished for the mutant Aspergillus sp. XN15. With the optimal fermentation conditions, and a solid medium supplemented with nitrogen sources of 1% urea and 1% $NH_4NO_3$, 2.5 mM $CoSO_4$, 0.05% (v/w) Tween 80, and 1% glucose, the mutant Aspergillus sp. XN15 produced the raw-starch-digesting enzyme in quantities 19.4 times greater than a typical wild variety. Finally, XN15, through simultaneous saccharification and fermentation of a raw rice corn starch slurry, produced a high level of ethanol with $Y_{p/s}$ of 0.47 g/g.