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91.
Ruminal bacteria from axenic cultures of Ruminococcus flavefaciens FD1, Butyrivibrio fibrisolvens 49, and bacterial types from the ruminal ecosystem that were fixed with 50 mM lysine (l-lysine hydrochloride) added to glutaraldehyde had better-preserved capsules and extracellular material than bacteria fixed without lysine. 相似文献
92.
Feruloyl and p-coumaroyl esterase from anaerobic fungi in relation to plant cell wall degradation 总被引:1,自引:0,他引:1
William S. Borneman Roy D. Hartley W. Herbert Morrison Danny E. Akin Lars G. Ljungdahl 《Applied microbiology and biotechnology》1990,33(3):345-351
Summary
Trans-feruloyl and trans-p-coumaroyl esterases were found in the culture filtrates of two monocentric (Piromyces MC-1, Neocallimastix MC-2) and three polycentric (Orpinomyces PC-2, Orpinomyces PC-3, and PC-1, an unnamed genus with uniflagellated zoospores) isolates of anaerobic rumen fungi. Treatment of cell walls of Coastal bermudagrass shoots with the filtrates released the trans isomers of ferulic and p-coumaric acids; results of microscopic observations indicated that fungal isolates degraded primarily unlignified cell walls in leaf blades and stems. A greater proportion of ferulic than p-coumaric acid was released by this treatment when compared with the amounts of the acids released by saponification of the walls with 1 M NaOH. The filtrates also showed esterase activities against the trans isomers of methyl ferulate and methyl p-coumarate, with ferulic acid being released at a faster rate than p-coumaric acid. Assays for other cell-wall-degrading enzymes (xylanase, -xylosidase, -l-arabinosidase, cellulase, -glucosidase) indicated that only -xylosidase correlated with ferulate and p-coumarate esterase activities. The monocentric isolate MC-2 had the highest esterase activity against both the plant cell wall and methyl ester substrates and the highest specific activities of acetyl esterase, -xylosidase, -l-arabinosidase, cellulase and -glucosidase. Isolate MC-2 produced substantially greater amounts of feruloyl and p-coumaroyl esterase when the growth substrate contained higher levels of saponifiable ferulic and p-coumaric acids.
Offprint requests to: W. S. Borneman 相似文献
93.
W F Hill W Jakubowski E W Akin N A Clarke 《Applied and environmental microbiology》1976,31(2):254-261
The sensitivity of several microporous virus-adsorbent media for reliably detecting low levels of poliovirus from 380 and 1,900 liters of drinking water by use of the tentative standard method was investigated. The virus-adsorbent media tested were (i) nitrocellulose membrane filters, (ii) epoxy-fiber glass-asbestos filters, (iii) yarn-wound fiber glass depth filters, and (iv) epoxy-fiber glass filter tubes. Virus was adsorbed to the filter media at pH 3.5 and eluted with glycine buffer, pH 11.5. The results from 44 samples demonstrated that poliovirus was detected with a 95% reliability at mean virus input levels of 3 to 7 plaque-forming units/380 liters when 1,900 liters of water was sampled. At mean virus input levels of less than 1 to 2 plaque-forming units/380 liters, the detection reliability was 66% in 76 samples when 1,900 liters of water was sampled. No significant difference in virus detection sensitivity was observed among the various virus adsorbent media tested. Overall virus recovery efficiency ranged from 28 to 42%, with a grand average of 35%. Members of the coxsackievirus groups A and B, echovirus, and adenovirus were also detected when 380 and 1,900 liters of water were sampled. These experimental observations attest to the sensitivity of the tentative standard method for detecting low levels of virus in large volumes of drinking water. 相似文献
94.
Detection of virus in water: sensitivity of the tentative standard method for drinking water. 总被引:11,自引:10,他引:1 下载免费PDF全文
The sensitivity of several microporous virus-adsorbent media for reliably detecting low levels of poliovirus from 380 and 1,900 liters of drinking water by use of the tentative standard method was investigated. The virus-adsorbent media tested were (i) nitrocellulose membrane filters, (ii) epoxy-fiber glass-asbestos filters, (iii) yarn-wound fiber glass depth filters, and (iv) epoxy-fiber glass filter tubes. Virus was adsorbed to the filter media at pH 3.5 and eluted with glycine buffer, pH 11.5. The results from 44 samples demonstrated that poliovirus was detected with a 95% reliability at mean virus input levels of 3 to 7 plaque-forming units/380 liters when 1,900 liters of water was sampled. At mean virus input levels of less than 1 to 2 plaque-forming units/380 liters, the detection reliability was 66% in 76 samples when 1,900 liters of water was sampled. No significant difference in virus detection sensitivity was observed among the various virus adsorbent media tested. Overall virus recovery efficiency ranged from 28 to 42%, with a grand average of 35%. Members of the coxsackievirus groups A and B, echovirus, and adenovirus were also detected when 380 and 1,900 liters of water were sampled. These experimental observations attest to the sensitivity of the tentative standard method for detecting low levels of virus in large volumes of drinking water. 相似文献
95.
D E Akin 《Applied microbiology》1976,31(4):562-568
The degradation of forage cell walls by rumen bacteria was investigated with critical-point drying/scanning electron microscopy and ruthenium red staining/transmission electron microscopy. Differences were observed in the manner of attachment of different morphological types of rumen bacteria to plant cell walls during degradation. Cocci, constituting about 22% of the attached bacteria, appeared to be attached to degraded plant walls via capsule-like substances averaging 58 nm in width (range, 21 to 84 nm). Many bacilli appeared to adhere to forage substrates without distinct capsule-like material, although unattached bacteria with capsules were observed occasionally. Certain bacili appeared to be attached to degraded tissue via small amounts of extracellular material, but others apparently had no extracellular material. Bacilli with a distinct morphology due to an irregularly folded, electron-dense outer layer or layers (about 15 nm thick) and without fibrous extracellular material consituted about 37% of the attached bacteria and were observed to adhere so closely to degraded plant walls that the bacterial shape conformed to the shape of the degraded zone. In the rumen ecosystem, bacteria appeared to adhere to plant substrates during degradation by capsule-like material and by small amounts of extracellular material, as well as by the other means not observable by electron microscopy. 相似文献
96.
Ultraviolet Devitalization of Eight Selected Enteric Viruses in Estuarine Water 总被引:2,自引:2,他引:0 下载免费PDF全文
William F. Hill Jr. Frederick E. Hamblet William H. Benton Elmer W. Akin 《Applied microbiology》1970,19(5):805-812
The effect of ultraviolet (UV) radiation on the devitalization of eight selected enteric viruses suspended in estuarine water was determined. The surviving fractions of each virus were calculated and then plotted against the UV exposure time for purposes of comparison. Analytical assessment of the survival data for each virus consisted of least squares regression analysis for determination of intercepts and slope functions. All data were examined for statistical significance. When the slope function of each virus was compared against the slope function of poliovirus type 1, the analytical findings indicated that poliovirus types 2 and 3, echovirus types 1 and 11, and coxsackievirus A-9 exhibited similar devitalization characteristics in that no statistically significant difference was found (P > 0.05). Conversely, the devitalization characteristics of coxsackievirus B-1 and reovirus type 1 were dissimilar from those of poliovirus type 1 in that a statistically significant difference was found between the slope functions (P < 0.05). This observed difference in devitalization of coxsackievirus B-1 and reovirus type 1 was attributed primarily to the frequency distribution of single and aggregate virions, the geometric configuration, the size of the aggregates, and the severity of aggregation. The devitalization curve of coxsackievirus B-1 was characteristic of a retardant die-away curve. The devitalization curve of reovirus type 1 was characteristic of a multihittype curve. The calculated devitalization half-life values for poliovirus types 1, 2, and 3; echovirus types 1 and 11; coxsackievirus types A-9 and B-1; and reovirus type 1 were 2.8, 3.1, 2.7, 2.8, 3.2, 3.1, 4.0, 4.0 sec, respectively. These basic data should facilitate an operative extrapolation of the findings to the applied situation. It was concluded that UV can be highly effective and provide a reliable safety factor in treating estuarine water. 相似文献
97.
D E Akin 《Applied microbiology》1987,53(8):1955-1958
Treatment of fibrous residue from in vitro digestion trials with chitinase was evaluated gravimetrically and microscopically to determine the associated fungal biomass. The percent dry weight removed by chitinase with time paralleled changes in the number of sporangia associated with leaves. The fungal biomass contributed about 12% dry matter to the residue of leaves incubated with ruminal fluid plus streptomycin and penicillin. 相似文献
98.
Akin S 《Plastic and reconstructive surgery》2004,113(7):2221-2222
99.
Biodegradation of lignocellulose in Bermuda grass by white rot fungi analyzed by solid-state 13C nuclear magnetic resonance. 总被引:1,自引:1,他引:0 下载免费PDF全文
Following the solid-state fermentation of Bermuda grass by two lignin-degrading white rot fungi, compositional changes have been observed in situ by utilization of cross-polarization and magic angle spinning 13C nuclear magnetic resonance difference spectra and interrupted decoupling spectra. Intensity differences in the 13C resonances assigned to specific components of the cell wall were used to observe these changes. Bermuda grass treated with Phanerochaete chrysosporium K-3 exhibited losses primarily in the polysaccharide components, with a smaller proportion of phenolic components also being degraded. In contrast, Ceriporiopsis subvermispora FP 90031-sp removed a proportionate amount of phenolic components compared with polysaccharide components. The results also indicated that C. subvermispora preferentially removes guaiacyl phenolic components relative to syringyl phenolic components, while P. chrysosporium was nonspecific in its attack on phenolic components. 相似文献
100.
Fluid dynamics of anaerobic fermentation 总被引:2,自引:0,他引:2
In beer fermentation, yeast cells are kept in suspension, despite their higher density, by natural agitation created by ascending CO2 bubbles. Yeast cells are unable to nucleate bubbles but instead release CO2 in a soluble form in such a way that the medium tends to become supersaturated. A higher concentration of yeast cells and the presence of solid particles cause the formation of bubbles at the bottom of the fermenter and practically only there. The rising bubbles grow and accelerate by sweeping the CO2 formed throughout the fermenter by the suspended yeast cells, thereby creating a fluid regime. A mathematical expression relating the bubble agitation power to the fermentation parameters was obtained and used to design more efficient fermenter shapes. 相似文献