摘要:

AbstractThe increasing interest in alcohol fermentation over these last years because of the energy crisis has been demonstrated by an increase in scientific research. After a brief analysis of the main results of the literature in the field of alcohol fermentation reactors, the use of a new type of immobilized cell reactor [the rotating biological surface (RBS) reactor] was studied. As is well known, the RBS reactor is a form of fixed‐film reactor and can be described as a dynamic trickling filter. Our experimental apparatus employed a spongy material to trap the yeast cells on the disks. The results of fermentations carried out in the RBS reactor working in batch, in continuous with cell support, and in continuous without cell support have been presented in order to compare the different productivities and to assess the performance of the RBS immobilized cell reactor. An ethanol productivity of 7.1 g/L h was achieved in the RBS‐ICR at a dilution rate of 0.3 h−1, 2.5 times higher than the maximum productivity obtained in the RBS reactor without support at a lower dilution rate. The adoption of a spongy material as a cell immobilizer, combined with the use of the RBS reactor, enhances the particular advantages of both sy

ISSN:0006-3592    

DOI:10.1002/bit.260270602

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY

摘要:

AbstractAs part of the development of a comprehensive mathematical model for chitinase production bySerratia marcescensQMB 1466 growing on chitin, the different mass transport and kinetic steps involved during chitin hydrolysis were studied. The experimental results for the hydrolysis of chitin by a crude preparation of chitinase show a system kinetically limited by the overall rate of chitin hydrolysis. This rate is linearly related to the concentration of enzyme adsorbed on the chitin particle. Adsorbed and bulk enzyme concentration were found to be related through a Langmuir type of isotherm.

ISSN:0006-3592    

DOI:10.1002/bit.260270603

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY

摘要:

AbstractA comprehensive model for chitinase production during growth ofSerratia marcescensQMB 1466 on chitin was developed taking into account the rate of chitin hydrolysis in order to estimate the rate of bacterial growth. In relating growth with enzyme synthesis the total enzyme concentration was used as the sum of the enzyme present in the bulk of the fermentation broth and the enzyme adsorbed on the chitin particles. The equations constituting the proposed model were fitted to the experimental results from both continuous and batch fermentation to obtain parameters describing substrate yield, metabolic maintenance, and enzyme yields.

ISSN:0006-3592    

DOI:10.1002/bit.260270604

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY

摘要:

AbstractA strain ofPenicillium funiculosum, isolated in this laboratory, produced in high yield both endo‐ and exo‐glucanases and β‐glucosidases, which were suitable for the saccharification of cellulosic materials. The isolation of the β‐glucosidase of this organism, which differs from other β‐glucosidases of fungi in its substrate specificity, by preparative electrophoresis, is described in this article. The organism was grown on a lactose‐casein medium and the culture filtrate concentrated by ammonium sulfate precipitation and dialysis. Electrophoresis was carried out on large slabs of polyacrylamide gel in an anodicrun in the presence of borate at pH 7. After elution of active fractions, a cathodic run was made at pH 6.0. Two precipitations with ammonium sulfate resulted in a homogeneous enzyme (specific activity 174 IU/mg). A second isozyme was also produced byP. funiculosumon cellulose‐wheat bran medium. This isozyme was purified by electrophoresis at pH 7.0 in the absence of borate and was obtained free from other isozymes of β‐glucosi

ISSN:0006-3592    

DOI:10.1002/bit.260270605

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY

摘要:

AbstractThe properties of two isozymes of β‐glucosidase ofPenicillium funiculosum(part I of this series) are described. The molecular weights of isozyme 1 was 2.3 × 105by gel filtration and 1.2 × 105by SDS gel electrophoresis, indicating two subunits. The molecular weight of isozyme 2 was unusually low for a fungal β‐glucosidase: 1.6 × 104by gel filtration and 3.7 × 104in the presence of isopropanol. The two enzymes differed from other fungal β‐glucosidases in their substrate specificities. They showed high activity withpNPG, cellobiose, cellotriose, cellotetraose, cellopentaose, gentiobiose, and laminarin, but were inactive with filter paper, CM cellulose, or derivatives or stabilized by bovine serum albumin and several alcohols such as butanol and propanol. It was inhibited by glucono‐δ‐lactone (Ki= 0.67μM) and glucose (Ki= 0.92mM).The enzyme was quantitatively adsorbed byP. funiculosummycelium at pH 4 and the immobilized enzyme was as enzymically active as the free enzyme, but more heat stable. The binding efficiency was very high (5000 IU enzyme/g mycelium). It could be quantitatively eluted with buffers at pH 7 or by 0.02MCa, Mg, or Al chlorides. The binding was selective, since mycelium grown on lactose could produce and also bind only β‐glucosidase isozyme 1, whereas mycelium grown on cellulose could produce as well as bind both β‐glucosidase isozymes as well as cellulases. Mycelial binding was unaffected by washing with EDTA or trypsinization, but was totally lost by washing with dilute KOH,

ISSN:0006-3592    

DOI:10.1002/bit.260270606

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY

摘要:

AbstractThe balances of reductivity and high‐energy bonds (HEB) during microbial growth on glucose (a standard substrate), methanol, and ethanol are reported. Also, numerical values for the quantities of HEB formation in the respiratory metabolism, HEB consumption in the constructive metabolism, as well as in a number of the other intracellular processes are evaluated. Estimations of maximum cell yields by mass and energy are made during growth on methanol and ethanol with regard to peculiar features of different microbe metabolis

ISSN:0006-3592    

DOI:10.1002/bit.260270607

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY

摘要:

AbstractA new hybrid reactor, the upflow blanket filter (UBF), which combined on open volume in the bottom two‐thirds of the reactor for a sludge blanket and submerged plastic rings (Flexiring, Koch Inc., 235 m2/m3) in the upper one‐third of the reactor volume, was studied. This UBF reactor was operated at 27°C at loading rates varying from 5 to 51 g chemical oxygen demand (COD)/L d with soluble sugar wastewater (2500 mg COD/L). Maximum removal rates of 34 g COD/L d and CH4production rates of 7 vol/vol d [standard temperature and pressure (STP)] were obtained. The biomass activity was about 1.2 g COD/g volatile suspended solids per day. Conversion (based on effluent soluble COD) was over 93% with loading rates up to 26 g COD/L d. At higher loading rates conversion decreased rapidly. The packing was very efficient in retaining bio

ISSN:0006-3592    

DOI:10.1002/bit.260270608

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY

摘要:

AbstractIn addition to the role of maintaining the pH, buffers can also facilitate the transport of H+ions in acid‐generating systems. The role of this facilitation in proton transport in porous pellets on acid‐generating immobilized enzymic reactions is examined. The activity in these systems can be maximized by a proper control of facilitation, which involves the determination of the appropriate variables out of (1) the concentration of the weak acid, (2) the pH of the medium, (3) the bulk substrate concentration, and (4) the type of weak acid. Since the intrinsic activity (IA) of the immobilized enzyme is such that it exhibits an optimum with respect to the pH, a partial (optimal) removal of diffusional limitation by facilitation maximizes the activity when the bulk pH is larger than this optimum pH. A complete removal of diffusional limitations, however, maximizes the activity when the bulk pH is less than or equal to the above optimum pH. The control of the diffusional resistance can be achieved by controlling the extent of facilitation, hence by adjusting the parameters mentioned above. Computations have been carried out to examine the effect of each of these parameters on the activity of the immobilized enzyme. It is found that when the bulk pH is less than or equal to the optimum pH of the intrinsic activity of the immobilized enzyme, there exists a lower limit on the amount of weak acid required to maximize the activity. However, an optimum amount of weak acid is required to maximize the activity when the bulk pH is higher than that optimum pH. For a given activity the amount of weak acid is minimal if the pKof the weak acid is close to the bulk pH. The effect of coupling between the proton and substrate transport on activity control is also examined and the effect of geometry on activity is evaluated for spherical, cylindrical, and flat‐plate configura

ISSN:0006-3592    

DOI:10.1002/bit.260270609

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY

摘要:

AbstractA control system has been devised for the maintenance of stable ammonium concentrations throughout a fedbatch fermentation. The control system is based on an ammonia gas‐sensing electrode that monitors a pH‐adjusted effluent stream from the fermentor. To overcome the time lag between the fermentor and the electrode, feedback control included metered flows of ammonium to both the fermentor and the electrode vessel. The system was used to study the growth ofEscherichia coliB (ATCC 11303) at controlled ammonium concentrations of 5 to 200mM. Apparent specific growth rates, biomass and protein production, and glucose yields were essentially constant from 5 to 170mM. Above 170mMammonium growth was inhibited. As ammonium concentration decreased from 170 to 5mM, ammonium yields increased from 1 to 24 g cell dry wt/g ammonium utilized. The results demonstrate that control of ammonium concentrations at levels so low that ammonium would be exhausted in batch fermentations can significantly increase overall ammonium yie

ISSN:0006-3592    

DOI:10.1002/bit.260270610

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY

摘要:

AbstractParticles of the hydrophobic resin polydimethylsiloxane were found to preferentially accumulate steriods on the basis of their hydrophobicity. Thus, the resin selectively sorped the steroid products resulting from the transformation of diosgenin byNocardia rhodochrous, with the result that higher yields of the later biotransformation product, 1‐dehydrodiosgenone, and lower yields of the first product, diosgenone, were obtained than in the absence of resin. Furthermore, steroids accumulated by the resin were available for further biotransformation, so that a two‐step reaction forming androstenes from a crude extract of furostanol glycosides (obtained from fenugreek seed) could be carried out. The first step involves deglycosylation and is catalyzed byFusarium solani. In the presence of resin the water‐insoluble diosgenin product becomes sorped to the resin and can be easily transferred to a second fermentation in which diosgenone, 1‐dehydrodiosgenone, and androstenes were formed byMycobacterium phlei. These compounds were completely accumulated by the resin at the end of the fermentation. This procedure is logistically more convenient than the conventional chemical process and illustrates the potential of biotechnological processes in which simultaneous reaction, product isolation, and product purificatio

ISSN:0006-3592    

DOI:10.1002/bit.260270611

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY