• Microbiology and Biotechnology Letters
• /
• v.24 no.6
• /
• pp.717-725
• /
• 1996

We have developed an efficient immobilized cell separator for continuous operation of immobilized fungal cell cultures, and applied this separator to actual fermentation process for the production of cyclosporin A (CyA), a powerful immunosuppressant. In the experiments employing highly viscous polymer (carboxymethyl cellulose) solution, the decantor showed good separating performances at high solution viscosites and fast dilution rates. Air duct and cylindrical separator installed inside the decantor turned out to play key roles for the efficient separation of the immobilized cells. By installing the decantor in an immobilized perfusion reactor system (IPRS), continuous immobilized culture was stably carried out even at high dilution rate for a long period, leading to high productivities of free cells and CyA. Almost no immobilized biomass existed in effuluent stream of the IPRS, demonstrating the effectiveness of the decan- tor system for a long-term continuous fermentation. It was noteworthy that we could obtain these results despite of the unfavorable fermentation conditions, i.e., reduced density of the biosupports caused by overgrowth of cells inside the bead particles and existence of high density of suspended fungal cells (10g/l) in the fermentation broth.

• Asian-Australasian Journal of Animal Sciences
• /
• v.17 no.6
• /
• pp.820-824
• /
• 2004

The study was to see the effect of administration of ruminal fungi on feed intake, growth rate, rumen fermentation and nutrient digestion of calves (Tharparkar$\times$Holstein-Friesian, average age: 10 months, average body weight: 130 kg). The 6 calves in first group were fed a mixture consisted of 50% wheat straw and 50% concentrate (Maize 62%, Groundnut cake 35%, Mineral mix. 2% and Common salt 1%) along with 1 kg green oats $animal^{-1}$ $day^{-1}$ while second group calves were fed the above-mentioned diet in addition to a dose of 160 ml ($10^{6}$ CFU/ml) fungal culture $calf^{-1}$ $week^{-1}$. The average dry matter intake per day was slightly lowered in fungal fed calves yet feed conversion ratio was higher. The average daily weight gain was significantly higher (15.37%) in fungal administered group as compared to control. The nutrient digestibility was increased for crude fibre, NDF and ADF with fungal administration. Digestible energy value of straw-based diet in terms of percent TDN also increased. The pH and $NH_{3}$-N were lower whereas TVFA, total-N, TCA-N and number of zoospores were higher in rumen liquor in fungal administered group.

• 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.31 no.7
• /
• pp.1028-1034
• /
• 2021

The effect of medium composition on enzyme and β-glucan production by Aspergillus oryzae KCCM 12698 was investigated. Brown rice, rice bran, nitrogen, and ascorbic acid are key components of the synthetic medium used in liquid-state fermentation. To determine the optimal concentrations of these components for enzyme and β-glucan production, we conducted one factor at a time experiments, which showed that the optimal concentrations were 30 g/l brown rice, 30 g/l rice bran, 10 g/l soytone, and 3 g/l ascorbic acid. Pretreatment of brown rice for 60 min prior to inoculation enhanced fungal biomass, while increasing the production of enzymes and β-glucan using solid-state fermentation. Maximum fungal biomass of 0.76 mg/g, amylase (26,551.03 U/g), protease (1,340.50 U/g), and β-glucan at 9.34% (w/w) were obtained during fermentation. Therefore, solid-state fermentation of brown rice is a process that could enhance yield and overall production of enzymes and β-glucan for use in various applications.

• Journal of Microbiology and Biotechnology
• /
• v.21 no.12
• /
• pp.1270-1279
• /
• 2011

Bealmijang is a short-term aged paste made from meju, which is a brick of fermented soybeans and other ingredients. Different types of bealmijang are available depending on the geographic region or ingredients used. However, no study has clarified the microbial diversity of these types. We identified 17 and 14 fungal species from black soybean meju (BSM) and buckwheat meju (BWM), respectively, on the basis of morphology, culture characteristics, and internal transcribed spacer and ${\beta}$-tubulin gene sequencing. In both meju, Aspergillus oryzae, Rhizopus oryzae, Penicillium polonicum, P. steckii, Cladosporium tenuissimum, C. cladosporioides, C. uredinicola, and yeast species Pichia burtonii were commonly found. Moreover, A. flavus, A. niger, P. crustosum, P. citrinum, Eurotium niveoglaucum, Absidia corymbifera, Setomelanomma holmii, Cladosporium spp. and unclassified species were identified from BSM. A. clavatus, Mucor circinelloides, M. racemosus, P. brevicompactum, Davidiella tassiana, and Cladosporium spp. were isolated from BWM. Fast growing Zygomycetous fungi is considered important for the early stage of meju fermentation, and A. oryae and A. niger might play a pivotal role in meju fermentation owing to their excellent enzyme productive activities. It is supposed that Penicillium sp. and Pichia burtonii could contribute to the flavor of the final food products. Identification of this fungal diversity will be useful for understanding the microbiota that participate in meju fermentation, and these fungal isolates can be utilized in the fermented foods and biotechnology industries.

• 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.

• Journal of Microbiology and Biotechnology
• /
• v.27 no.1
• /
• pp.101-111
• /
• 2017

The task of improving a fungal strain is highly time-consuming due to the requirement of a large number of flasks in order to obtain a library with enough diversity. In addition, fermentations (particularly those for fungal cells) are typically performed in high-volume (100-250 ml) shake-flasks. In this study, for large and rapid screening of itaconic acid (IA) high-yielding mutants of Aspergillus terreus, a miniaturized culture method was developed using 12-well and 24-well microtiter plates (MTPs, working volume = 1-2 ml). These miniaturized MTP fermentations were successful, only when highly filamentous forms were induced in the growth cultures. Under these conditions, loose-pelleted morphologies of optimum sizes (less than 0.5 mm in diameter) were casually induced in the MTP production cultures, which turned out to be the prerequisite for the active IA biosynthesis by the mutated strains in the miniaturized fermentations. Another crucial factor for successful MTP fermentation was to supply an optimal amount of dissolved oxygen into the fermentation broth through increasing the agitation speed (240 rpm) and reducing the working volume (1 ml) of each 24-well microtiter plate. Notably, almost identical fermentation physiologies resulted in the 250 ml shake-flasks, as well as in the 12-well and 24-well MTP cultures conducted under the respective optimum conditions, as expressed in terms of the distribution of IA productivity of each mutant. These results reveal that MTP cultures could be considered as viable alternatives for the labor-intensive shake-flask fermentations even for filamentous fungal cells, leading to the rapid development of IA high-yield mutant strains.

• Mycobiology
• /
• v.43 no.3
• /
• pp.218-224
• /
• 2015

Aspergillus is an important fungal genus used for the fermentation of Asian foods; this genus is referred to as koji mold in Japan and China. A. oryzae, A. sojae, and A. tamari are used in the production of miso and shoyu in Japan, but a comprehensive taxonomic study of Aspergillus isolated from Meju, a fermented soybean starting material for traditional soy sauce and soybean paste in Korea, has not been conducted. In this study, various Aspergillus species were isolated during a study of the mycobiota of Meju, and the aspergilli were identified based on phenotypic characteristics and sequencing of the ${\beta}$-tubulin gene. Most strains of Aspergillus were found to belong to the following sections: Aspergillus (n = 220), Flavi (n = 213), and Nigri (n = 54). The most commonly identified species were A. oryzae (n = 183), A. pseudoglaucus (Eurotium repens) (n = 81), A. chevalieri (E. chevalieri) (n = 62), A. montevidensis (E. amstelodami) (n = 34), A. niger (n = 21), A. tamari (n = 15), A. ruber (E. rubrum) (n = 15), A. proliferans (n = 14), and A. luchuensis (n = 14); 25 species were identified from 533 Aspergillus strains. Aspergillus strains were mainly found during the high temperature fermentation period in the later steps of Meju fermentation.

• Journal of Microbiology and Biotechnology
• /
• v.24 no.11
• /
• pp.1455-1463
• /
• 2014

In the past, reactive oxygen species (ROS) have been considered a harmful byproduct of aerobic metabolism. However, accumulating evidence implicates redox homeostasis, which maintains appropriate ROS levels, in cell proliferation and differentiation in plants and animals. Similarly, ROS generation and signaling are instrumental in fungal development and host-fungus interaction. In fungi, NADPH oxidase, a homolog of human $gp91^{phox}$, generates superoxide and is the main source of ROS. The mechanism of activation and signaling by NADPH oxidases in fungi appears to be largely comparable to those in plants and animals. Recent studies have shown that the fungal NADPH oxidase homologs NoxA (Nox1), NoxB (Nox2), and NoxC (Nox3) have distinct functions. In particular, these studies have consistently demonstrated the impact of NoxA on the development of fungal multicellular structures. Both NoxA and NoxB (but not NoxC) are involved in host-fungus interactions, with the function of NoxA being more critical than that of NoxB.

• 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.