Effect of operational conditions on the rate of citric acid production by rotating disk contactor using Aspergillus niger

Sakurai, Akihiko; Imai, Hiroshi

doi:10.1016/0922-338x(92)90175-t

Cited by 12 publications

(5 citation statements)

References 17 publications

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“…Attached growth of A. niger on glasscarrier in a fixed-bed agitated system did not produced higher levels of citric acid as compared to still-surface cultures and shaken flasks [166]. However, A. niger immobilized on porous cellulose beads or cubes in shaken flasks or on the vertical discs of a rotating disc contactor attained 2-fold higher productivities than conventional submerged cultures and repeated batch cultivation could be extended up to six repeated cycles of 6-day interval [167][168][169][170][171]. Interestingly, this group led by Akihiko Sakurai used the term biofilm to refer to the attached biomass of A. niger on a support though the concept was of immobilization.…”

Section: Metabolite and Enzyme Production Of Aspergillus Biofilmsmentioning

confidence: 83%

Recent Advances on Filamentous Fungal Biofilms for Industrial Uses

Gutiérrez-Correa

Ludeña

Ramage

et al. 2012

Appl Biochem Biotechnol

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Industrial enzymes are produced by submerged fermentation (SF) and by solid-state fermentation (SSF) to a lesser extent. Although SSF has several advantages, its scale-up is difficult. The role of physiological and genetic properties of microorganisms growing attached to surfaces could explain the advantages of SSF. Filamentous fungi are naturally adapted to growth on surfaces and in these conditions they show a particular physiological behavior which is different from that in SF; thus, they also form biofilms. Fermentation by filamentous fungal biofilms (FFB) is a homogeneous production system within a liquid environment based on the infrastructure of the SF process with the productive efficiency of the SSF. Enzyme production levels of FFB are much higher than those obtained in SF and they are also amenable of mixed fungal cultivation. Transcriptomic and proteomic tools are used to uncover the fundamental biological issues behind FFB. Several genes encoding cellulolytic enzymes are either differentially expressed or overexpressed in FFB. Moreover, our proteomic studies of Aspergillus niger biofilms compared to SF indicate that many intracellular proteins are either differentially expressed or overexpressed. Clinically important fungi like A. fumigatus also form biofilms when they infect lungs and recent studies demonstrate same gene expression features. These results support our hypothesis of cell adhesion and its role in the new schemes for improved fermentative production of industrial enzymes.

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Section: Metabolite and Enzyme Production Of Aspergillus Biofilmsmentioning

confidence: 83%

Recent Advances on Filamentous Fungal Biofilms for Industrial Uses

Gutiérrez-Correa

Ludeña

Ramage

et al. 2012

Appl Biochem Biotechnol

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“…The oxygenated culture produced twice as much glucose oxidase as the aerated one. Sakurai and Imai (1992) found that the specific citric acid production rate increased with the dissolved oxygen tension in a rotating disk contactor using A. niger. Giuseppin (1984) showed that lipase production of Rhizopus delemar decreased when the dissolved oxygen tension was lower than about 18% of air saturation.…”

Section: Introduction General Aspectsmentioning

confidence: 95%

Effects of dissolved oxygen tension and mechanical forces on fungal morphology in submerged fermentation

Cui

Lans

Luyben

1998

Biotechnol. Bioeng.

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The effects of dissolved oxygen tension and mechanical forces on fungal morphology were both studied in the submerged fermentation of Aspergillus awamori. Pellet size, the hairy length of pellets, and the free filamentous mycelial fraction in the total biomass were found to be a function of the mechanical force intensity and to be independent of the dissolved oxygen tension provided that the dissolved oxygen tension was neither too low (5%) nor too high (330%). When the dissolved oxygen concentration was close to the saturation concentration corresponding to pure oxygen gas, A. awamori formed denser pellets and the free filamentous mycelial fraction was almost zero for a power input of about 1 W/kg. In the case of very low dissolved oxygen tension, the pellets were rather weak and fluffy so that they showed a very different appearance. The amount of biomass per pellet surface area appeared to be affected only by the dissolved oxygen tension and was proportional to the average dissolved oxygen tension to the power of 0.33. From this it was concluded that molecular diffusion was the dominant mechanism for oxygen transfer in the pellets and that convection and turbulent flow in the pellets were negligible in submerged fermentations. The biomass per wet pellet volume increased with the dissolved oxygen tension and decreased with the size of the pellets. This means that the smaller pellets formed under a higher dissolved oxygen tension had a higher intrinsic strength. Correspondingly, the porosity of the pellets was a function of the dissolved oxygen tension and the size of pellets. Within the studied range, the void fraction in the pellets was high and always much more than 50%.

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“…The initial values of S and C were the averages as shown in Table I and were assumed to be constant regardless of the value of A/V. However, the initial value of M was thought to change with A/V, as correlated with A/V by M e ‫ס‬ 15.4 ⅐ (A/V) −1 (Sakurai et al, 1992). A similar linear relationship was assumed to hold true at the starting point of the simulation, and the initial value of M for the simulation was estimated from the equation M i ‫ס‬ 0.977 × 4.02(A/V) −1 in referring to the average initial value of M in Table I.…”

Section: Effect Of Specific Biofilm Area On Citric Acid Production Ratementioning

confidence: 99%