• Food Science and Biotechnology
• /
• v.16 no.4
• /
• pp.590-593
• /
• 2007

The textural properties of doughs mixed with L-ascorbic acid (AA), trypsin hydrolyzed gluten peptide (THGP), and a mixture of AA-THGP were investigated using texture analyzer under the fermentation of the full formula and the freezing process. The full formula dough (FFD) required a shorter mixing time than the flour and water formula dough (FWD). The maximum resistance (Rmax) values of both the unfrozen and frozen doughs were lower for the FFD. The effects of AA and THGP additions were not significant (p<0.01) in FFD, however, they were significant in FWD. The freezing effect was significant (p<0.0001) for FFD, indicating that yeast fermented dough was much more sensitive to damage from freezing, which subsequently affected dough strength. Additions of AA (p=0.0026) and THGP (p=0.0097) had a significant effect on the extensibility (E-value) of unfrozen FWD, where THGP increased and AA decreased the E-value. However, freezing did not significantly effect the extensibilities of FWD (p=0.64) or FFD (p=0.21). The area of FFD was lower than the area of FWD for both the unfrozen and frozen doughs. However, the frozen dough mixed with THGP alone had the largest area overall. The addition of additives did not result in significantly different (p<0.01) areas under the curve, except in the frozen FFD. Freezing caused a statistically significant difference in the area of FWD (p=0.0045).

• Journal of Microbiology and Biotechnology
• /
• v.29 no.2
• /
• pp.256-267
• /
• 2019

The use of low-cost substrates represents one key issue to make single cell oil production sustainable. Among low-input crops, Arundo donax L. is a perennial herbaceous rhizomatous grass containing both C5 and C6 carbohydrates. The scope of the present work was to investigate and optimize the production of lipids by the oleaginous yeast Cutaneotrichosporon curvatus from undetoxified lignocellulosic hydrolysates of steam-pretreated A. donax. The growth of C. curvatus was first optimized in synthetic media, similar in terms of sugar concentration to hydrolysates, by applying the response surface methodology (RSM) analysis. Then the bioconversion of undetoxified hydrolysates was investigated. A fed-batch process for the fermentation of A. donax hydrolysates was finally implemented in a 2-L bioreactor. Under optimized conditions, the total lipid content was 64% of the dry cell weight and the lipid yield was 63% of the theoretical. The fatty acid profile of C. curvatus triglycerides contained 27% palmitic acid, 33% oleic acid and 32% linoleic acid. These results proved the potential of lipid production from A. donax, which is particularly important for their consideration as substitutes for vegetable oils in many applications such as biodiesel or bioplastics.

• Journal of Life Science
• /
• v.26 no.8
• /
• pp.976-982
• /
• 2016

Seaweed has high growth rate, low land usage, high CO₂ absorption and no competition for food resources. Therefore, the use of lignin-free seaweed as a raw material is arising as a third generation biomass for bioethanol production. Various pretreatment techniques have been introduced to enhance the overall hydrolysis yield, and can be categorized into physical, chemical, biological, enzymatic or a combination. Thermal acid hydrolysis pretreatment is one of the most popular methods to attain high sugar yields from seaweed biomass for economic reasons. At thermal acid hydrolysis conditions, the 3,6-anhydro-galactose (AHG) from biomass could be converted to 5-hydroxymethylfurfural (HMF), which might inhibit the cell growth and decrease ethanol production. AHG is prone to decomposition into HMF, due to its acid-labile character, and subsequently into weak acids such as levulinic acid and formic acid. These inhibitors can retard yeast growth and reduce ethanol productivity during fermentation. Thus, the carbohydrates in seaweed require effective treatment methods to obtain a high concentration of monosaccharides and a low concentration of inhibitor HMF for ethanol fermentation. The efficiency of bioethanol production from the seaweed biomass hydrolysate is assessed by separate hydrolysis and fermentation (SHF). To improve the efficiency of the ethanol fermentation of mixed monosaccharides, the adaptation of yeast to high concentration of sugar could make simultaneous utilization of mixed monosaccharides for the production of ethanol from seaweed.

• Journal of Environmental Science International
• /
• v.16 no.10
• /
• pp.1203-1208
• /
• 2007

Feathers are produced in huge quantities as a waste product at commercial poultry processing plants. Since feathers are almost pure keratin protein, feather wastes represent an alternative to more expensive dietary ingredients for animal feedstuffs. Generally they become feather meal used as animal feed after undergoing physical and chemical treatments. These processes require significant energy and also cause environmental pollutions. Therefore, biodegradation of feather by microorganisms represents an alternative method to prevent environment contamination. The aim of this study was to investigate cultural conditions affecting keratinolytic protease production by Bacillus pumilus RS7. We also assessed the nutritive value of microbial and alkaline feather hydrolysates, The composition of optimal medium for the keratinolytic protease was fructose 0.05%, yeast extract 0.3%, NaCl 0.05%, K2HPO4 0.03%, KH2PO4 0.04% and MgCl2 6H2O 0.01%, respectively. The optimal temperature and initial pH was $30^{\circ}C$ and 9.0, respectively. The keratinolytic protease production under optimal condition reached a maximum after 18 h of cultivation. Total amino acid content of feather hydrolysates treated by NaOH and B. pumilius RS7 was $113.8\;{\mu}g/ml$ and $504.9\;{\mu}g/ml$, respectively. Essential amino acid content of feather hydrolysates treated by NaOH and B. pumilius RS7 was $47.2\;{\mu}g/ml$ and $334.0\;{\mu}g/ml$, respectively. Thus, feather hydrolysates have the potential for utilization as an ingredient in animal feed.

• Microbiology and Biotechnology Letters
• /
• v.9 no.2
• /
• pp.65-69
• /
• 1981

As a process to utilize agricultural residues, simultaneous hydrolysis-fermentation (SSF) was compared with fermentation of enzymic hydrolyzate using koji cultures of Trichoderma sp. KI 7-2 and a thermotolerant yeast Saccharomyces cerevisiae NCYC 716. Cellobiose was not detected in SSF broth whilst 15 mg/$m\ell$ of the disaccharide was found in enzymic hydrolysate of rice straw using the same enzyme source. It was found that converting glucose to ethanol in SSF process reactivated the cellobiase activity, which is inhibited by the accumulation of glucose in enzymic hydrolysis process. Cutting milled rice straw was fermented as effectively as ball milled one in SSF process. From tile results discussions are made on the product inhibition mechanism of cllulolytic enzyme system.

• Journal of Life Science
• /
• v.13 no.5
• /
• pp.618-625
• /
• 2003

Investigations were carried out to optimize the culture conditions for the production of xylanase by Paenibacillus sp. DG-22, a moderately thermophilic bacterium isolated from timber yard soil. Xylanase production showed a cell growth associated profile. Xylanase activity was found only in the culture supernatant, while $\beta-xylosidase$ activity was mainly associated with the cells. The formation of xylanase activity was induced by xylan and repressed by glucose and xylose. The production profile of xylanase was examined with various commercial xylan and maximum yield was achieved with 0.1∼ 0.5% birchwood xylan. Among various nitrogen sources tested, yeast extract was optimal for the production of xylanase. The xylanase activity was inhibited by $Co^{2+},\; Cu^{2+},\; Fe^{3+},\; Hg^{2+}\;$ and$\;Mn^{2+}$ ions while $Ca^{2+},\; Mg^{2+},\; Ni^{2+},\; Zn^{2+}$ions and DTT stimulated xylanase activity Mercury (II) ion at 5 mM concentration abolished all the xylanase activity. The predominant products of xylan-hydrolysate were xylobiose, xylotriose, and higher xylooligo-saccharides, indicating that the enzyme was an endoxylanase.

• The Korean Journal of Soil Zoology
• /
• v.7 no.1_2
• /
• pp.1-5
• /
• 2002

The pumpkin fruit fly [Bactrocera (paradacus) depressa Shiraki] was first trapped on June 1st with ground and Mcphail traps in Jinan and Iksan drea, Chonbuk Province and was found to have single generation during the grow-ing season in 2002. Not much difference existed in the number of B. (paradacus) depressa flies attracted to various colors but Bactrocera (zugodacus) scurellatus Hendal came to yellow and green more than to blue color. In a study of the effect of diets on the degree of attraction by the flies, it turned out that B. (paradacus) depressa came more to yeast hydrolysate (YH) and in June i.e, the early period of adult emergence of the year. However, more individuals of B. (zugodacus) scutellatus are attracted to the extract of young pumpkin fruits. More B. (paradacus) depressa was caught with McPhail traps while more B. (zugodacus) scurellatus was caught with sticky traps and accordingly, species specific traps are recommended when yearly population trends of fruit flies are studied.

• Mycobiology
• /
• v.48 no.6
• /
• pp.501-511
• /
• 2020

Xylophagous termites are capable of degrading lignocellulose by symbiotic gut microorganisms along with the host's indigenous enzymes. Therefore, the termite gut might be a potential niche to obtain natural yeasts with celluloytic, xylanolytic and ethanologenic traits required for bioethanol production from lignocellulosic biomass. In this study, we cultured 79 yeasts from three different termites viz. Coptotermes heimi, Odontotermes javanicus and Odontotermes obesus. After suitable screening methods, we identified 53 yeasts, which belonged to 10 genera and 16 different species of both ascomycetous and basidiomycetous yeasts. Most yeasts in the present study represent their first-ever isolation from the termite gut. Representative strains of identified yeasts were evaluated for their cellulolytic, xylanolytic, and ethanologenic abilities. None of the isolates showed cellulase activity; 22 showed xylanolytic activity, while six produced substantial quantities of ethanol. Among xylanolytic cultures, Pseudozyma hubeiensis STAG 1.7 and Hannaella pagnoccae STAG 1.14 produced 1.31 and 1.17 IU of xylanase. Among ethanologenic yeasts, the strains belonging to genera Candida and Kodamaea produced high amount of ethanol. Overall, highest ethanol level of 4.42 g/L was produced by Candida tropicalis TS32 using 1% glucose, which increased up to 22.92 g/L at 35 ℃, pH 4.5 with 5% glucose. Fermentation of rice straw hydrolysate gave 8.95 g/l of ethanol with a yield of 0.42 g/g using the strain TS32. Our study highlights the gut of wood-feeding termites as a potential source of diverse yeasts that would be useful in the production of xylanase and bioethanol.

• Microbiology and Biotechnology Letters
• /
• v.43 no.1
• /
• pp.9-15
• /
• 2015

The seaweed, Gracilaria verrucosa, was fermented to produce bioethanol. Optimal pretreatment conditions were determined to be 12% (w/v) seaweed slurry and 270 mM sulfuric acid at 121℃ for 60 min. After thermal acid hydrolysis, enzymatic saccharification was carried out with 16 U/ml of mixed enzymes using Viscozyme L and Celluclast 1.5 L to G. verrucosa hydrolysates. A total monosaccharide concentration of 50.4 g/l, representing 84.2% conversion of 60 g/l total carbohydrate from 120 g dw/l G. verrucosa slurry was obtained by thermal acid hydrolysis and enzymatic saccharification. G. verrucosa hydrolysate was used as the substrate for ethanol production by separate hydrolysis and fermentation (SHF). Ethanol production by Candida lusitaniae ATCC 42720 acclimated to high-galactose concentrations was 22.0 g/l with ethanol yield (Y_EtOH) of 0.43. Acclimated yeast to high concentrations of specific sugar could utilize mixed sugars, resulting in higher ethanol yields in the seaweed hydrolysates medium.

• Journal of Animal Science and Technology
• /
• v.45 no.2
• /
• pp.319-326
• /
• 2003

Angiotensin-I converting enzyme(ACE)inhibitor was isolated from beef by-products. The beef by- product hydrolysates prepared with various proteases were tested for the inhibitory effects against ACE. The proteases used were proteinase A from bakers yeast, protease type ⅩIII fungal and thermolysin. The maximum inhibitory effect was observed after hydrolysis for 12hrs(beef heart) and 24hrs(beef spleen), respectively. After gel filtration, IC50 value was 0.37mg/ml in beef heart and 1.84mg/ml in beef spleen. After RP-HPLC, the IC50 value of peak 1, peak 2, peak 3 and peak-4 were 0.28mg/ml, 0.26mg/ml, 0.25mg/ml and 0.35mg/ml, respectively. In the results of amino acid composition of peak 1, peak 2, peak 3 and peak 4, it was observed that peak 1 was consisted mainly of glycine and methionine, peak 2 was proline, cystine and methionine, peak 3 was proline and peak 4 was alanine, methionine and leucine. In conclusion, beef heart hydrolysate treated with thermolysin+ proteinase A was shown to have the highest inhibitory effect for 12hrs incubation at 37$^{\circ}C$.