摘要:

AbstractTrypsin was immobilized on sand using five different methods. Attempts were made to attach amino‐functional groups onto sand using 3‐aminopropyltriethoxysilane, hexamethylenetetramine, hexamethylenediamine, and melamine. Glutaraldehyde was used as a bifunctional agent in all the methods. Methods for the estimation of the proteolytic 1activity and protein content of immobilized trypsin were standardized. The maximum retained activity was observed for trypsin immobilized on sand via 3‐aminopropytriethoxysilane and glutaraldehyde. Immobilized trypsin showed a shift in the pH optimum toward the acidic side over that of soluble trypsin in all five cases. The optimum temperature for both native and immobilized trypsin prepared by the silane‐glutaraldehyde method was found to be 45°C. However, the pH and thermal stabilities of immobilized trypsin were observed to be better than that of the nativ

ISSN:0006-3592    

DOI:10.1002/bit.260220502

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

年代:1980

数据来源: WILEY

摘要:

AbstractThe population dynamics of continuous mixed cultures with pure commensalism, commensalism plus competitive assimilation, pure mutualism, and mutualism plus competitive assimilation was disused. The population does not display oscillatory phenomena where there is a single interaction of commensalism or mutualism. Damped oscillations take place when two interactions (such commensalism and competitive assimilation or mutualism and competitive assimilation) coexist in the continuous mixed culture. The stability of these systems was discussed in detail.

ISSN:0006-3592    

DOI:10.1002/bit.260220503

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

年代:1980

数据来源: WILEY

摘要:

AbstractA correlation for estimating the diffusion coefficients of protein molecules is presented. The correlation is based upon literature values of the protein diffusion coefficients and molal volumes for 143 proteins. The correlation can be used for the estimation of diffusion coefficients using only molecular weight. Accuracy is such that a linear regression on 301 proteins showed 75% of the diffusion coefficients estimated fell within 20% of the experimental values. The relationship between this correlation, the Stokes–Einstein equation, and the Wilke–Chang correlation is discus

ISSN:0006-3592    

DOI:10.1002/bit.260220504

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

年代:1980

数据来源: WILEY

摘要:

AbstractThe penetration of bovine serum albumin and penicillin acylase into Amberlite XAD7 beads was determined by staining split beads. The rates of penetration were measured and correlated with a theoretically derived equation.

ISSN:0006-3592    

DOI:10.1002/bit.260220505

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

年代:1980

数据来源: WILEY

摘要:

AbstractResearch intobulkingin laboratory‐scale activated‐sludge plants are reported upon. A correlation between sludge volume index (SVI) andbiopolymercontent (exocellular polymer, ECP) has been determined or sludge obtained under various operating conditions and with different chemical and physical characteristics. This paper interprets that correlation. A method for ECP determination that is quicker and just as precise as the gravimetric one and which enables this parameter to be used not only to interpretbioflocculationmechanisms but also as a parameter for evaluating optimal plant operation is repor

ISSN:0006-3592    

DOI:10.1002/bit.260220506

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

年代:1980

数据来源: WILEY

摘要:

AbstractIn a recent publication, a technique was outlined for measuring surface aeration rates in an agitated vessels while sparging, and it was shown that surface aeration rates fall rapidly with increasing sparge rates. That work was conducted in a 0.61 m diam vessels. The work reported here was done in a small vessel (0.22 m diam) where surface aeration has been reported to be of particular significance. In general, the results obtained in the small vessel confirmed those in the large one and in addition were generally in good agreement with those recently published elsewhere for an almost identical geometry. For typical practical power inputs and sparge rates, the rate of surface aeration was never more than 20% of the sparge rate and generally less than 5%. These results indicate that surface aeration is of considerably less importance than has generally been believed following the findings of workers who estimated its effect by comparingKLavalues under unsparged conditions with those when sparging.

ISSN:0006-3592    

DOI:10.1002/bit.260220507

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

年代:1980

数据来源: WILEY

摘要:

AbstractThe possibilities of using liquefied petroleum gas (LPG) heavy ends, predominantly volatile liquidn‐alkanes (a location‐specific hydrocarbon feedstock) for single‐cell protein (SCP) production are examined against criteria established to define potentially attractive SCP production processes. The factors discussed include the use of the heat of vaporization for fermentor cooling, the efficiency of conversion ofnalkane vapors, problems of maintaining constant composition substrates when feeding volatile liquidn‐alkane vapors to laboratory fermentors, the possible solvent effect of liquidn‐alkanes, and the possibilities of competitive inhibition. The study confirms that mixed volatilen‐alkane feedstocks will introduce major physical and biological problems for both product and process research and development. Even when the technical problems are solved, the economic question of whether a direct production route using the feedstock as the fermentation substrate or an indirect route involving the conversion of the feedstock, by chemical means, into methanol, which can then be used as the fermentation substrate, needs careful

ISSN:0006-3592    

DOI:10.1002/bit.260220508

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

年代:1980

数据来源: WILEY

摘要:

AbstractA postulated model of a biologically active fluidized bed is given, subject to various constraints.

ISSN:0006-3592    

DOI:10.1002/bit.260220509

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

年代:1980

数据来源: WILEY

摘要:

AbstractWhole cells ofBacillussp., a bacitracin‐producing bacteria, were immobilized in polyacrylamide gel. The continuous production of bacitracin by an immobilized whole‐cell‐containing air‐bubbled reactor was examined with 0.5% peptone solution. The bacitracin productivity (28 units/ml/hr) obtained with this system was higher than that with a batch system. The effluent bacitracin concentration increased with increasing aeration rate and reached a steady‐state maximum above the aeration rate of 3.0 liter/min. A high bacitracin productivity was retained for at least eight days when the gel was washed with sterilized saline at a flow rate of 250 ml/hr for 2 hr once a day. The half‐life of the immobilized whole‐cell system was about 10 days. Bacitracin productivity by the immobilized whole‐cell reactor was higher than that by a conventional continuous fermentation process at high

ISSN:0006-3592    

DOI:10.1002/bit.260220510

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

年代:1980

数据来源: WILEY

摘要:

AbstractIt has been shown that the rate of enzymatic saccharification of cellulosic materials including “pure” cellulose (Whatman CF−11 cellulose), newsprint, lignocellulose (prehydrolyzed to remove hemicelluloses), and wood can be substantially increased by simultaneous wet milling. An enhanced hydrolysis rate was sustained above that observed for ball milling: providing a more extensive saccharification. The cellulosic substrates were wet milled with a variety of grinding elements, such as sand, glass beads, and stainless‐steel beads, agitated in a shaker bath. Simultaneous hydrolysis was achieved with a 2% substrate slurry in a 0.1Macetate buffer at 45°C and pH 5. The effectiveness of this process was dependent upon the lignified matrix of the cellulose microfibrils, the grinding elements, and the oscillation frequency of the shaker bath. Wet milling “pure” cellulose for 48 hr, with 3.5 mm glass beads and 200 oscillations/min (opm), yielded 1031 mg reducing sugar/g substrates (93% saccharification) as compared to 483 mg (44%) for the ball‐milled sample and 253 mg (23%) for the unmilled material. With the lignified substrates stainless‐steel beads (3.5 mm) were more effective than glass. For lignocellulose 529 mg sugar/g substrate (93% saccharification) could be obtained by wet milling with cellulase for 24 hr. This was about three times greater than that of the ball milled (169 mg, 30%) and 10 times greater than that of the unmilled (52 mg, 9%) substrates. The method was also effective for wood particles (60 mesh) giving 143 mg sugar/g wood (approximately 38% saccharification) in 48 hr, whereas the ball‐milled sample gave only 79 mg (21%) and the unmlilled substrate 38 mg (10%). These observations can be explained on the basis of the current crystalline theory for the morphology of the cellulosic microfibrils. The advantage of wet milling and simultaneous hydrolysis apparently depends on a continuous generation of accessible sites and sustained rapid hydrolysis rate as the saccharification proceeds, where in the pretreated substrates the hydrolysis rate slow down as the active

ISSN:0006-3592    

DOI:10.1002/bit.260220511

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

年代:1980

数据来源: WILEY