Enzymatic treatment of primary municipal sludge with Trichoderma viride cellulase

Enzymatic hydrolysis of the cellulose in raw primary settled municipal sludge by Trichoderma viride cellulase achieved conversions of up to 75% of the cellulose, primarily to cellobiose, in 24 hr. Simultaneously the gel-like characteristic of raw primary sludge was changed to that of a slurry of fine particles in less than 2 hr, causing a radical change in the ability to ultrafilter the sludge. The use of raw primary sludge as a growth medium for T. viride cellulase production was also investigated. It was possible, with nitrogen supplements, to obtain an enzyme with a filter paper activity (FPA) of two compared to over four which is attainable on defined medium of similar strength. The potential use of cellulase treatment as a pretreatment or integral part of waste treatment processes is discussed and the alternatives evaluated.     

High-performance liquid chromatographic measurement of exogenous thiosulfate in urine and plasma

A simple technique using reverse-phase ion-pair liquid chromatography for measurement of exogenous thiosulfate is described. Accurate measurement of thiosulfate in plasma and urine was permitted by precolumn derivatization with monobromobimane, a substance that readily yields fluorescent compounds upon reaction with a variety of biologically important nucleophiles including glutathione, cysteine, and sulfite. Using an injection volume of 50 microliters, as little as 0.16 nmol of thiosulfate was reliably measured. The interassay precision of the method was reflected by a coefficient of variation of 7.7% while the coefficient of variation for interassay analysis was 2.6%. Recovery of thiosulfate from plasma was 96.9 +/- 3.2% and greater than 98% from urine. The simplicity, sensitivity, and precision of the method make it ideal for the study of thiosulfate and other important nucleophiles in body fluids.     

Mixed culture biooxidation of phenol. III. Existence of multiple steady states in continuous culture with wall growth

It is shown that two steady states exist in certain regions of operation of a 2-liter continuous stirred tank biological reactor. Transition was made from one steady state to another by applying shock loads of either phenol substrate which is inhibitory to the culture at high concentrations or by adding large additional amounts of concentrated organisms. The existence of the multiple steady states is ascribed to the existence of wall growth, and their position is determined by the amount of wall growth. Transient behavior of the system did not follow the predictions of the simple wall growth model but the culture appeared to undergo a lag period immediately after applying the shock load to the system. It is concluded that the stability of a continuous culture utilizing an inhibitory substrate is improved by increasing the degree of wall growth and decreasing the substrate feed concentration. It is also concluded that small scale experiments can usually not be interpreted correctly unless the effect of wall growth is taken into account.     

Heat of Combustion of Cells of Pseudomonas fluorescens

Based upon 161 determinations, the heat of combustion of cells of Pseudomonas fluorescens averaged 5.32 kcal/g on an ash-free dry-weight basis. The standard deviation was 0.39 kcal.     

Glycine-231 residue of the mouse mitochondrial protonmotive cytochrome b: mutation to aspartic acid deranges electron transport

The mouse LA9 HQN-R11 cytochrome b mutant, in which the glycine residue at position 231 is replaced by aspartic acid, has increased resistance to all inhibitors of the Qn redox center. It is shown here that this single amino acid alteration has multiple and unexpectedly diverse effects upon the mitochondrial protonmotive bc1 complex. (1) The specific activities of both succinate- and ubiquinol-cytochrome c oxidoreductases in isolated mitochondria are reduced by approximately 65% in the mutant. The parallel reductions in both oxidoreductase activities are not compatible with simple Q pool kinetics for mitochondrial electron transport. (2) There is also a reduction in the relative concentration of cytochrome b in the mutant when calculated on the basis of mitochondrial protein; this decrease does not account for more than a small portion of the reduced catalytic fluxes. (3) The increased antimycin resistance of the mutant is lost upon solubilization by the detergent dodecyl maltoside of the bc1 complex from mitochondria. (4) In pre-steady-state assays of cytochrome b reduction by quinol, the mutant shows a reduced extent of reduction. It was observed in other experiments that there was less oxidant-induced extrareduction of cytochrome b in the mutant. These results could arise from a lowering of the midpoint potentials of both the cytochrome b-562 and cytochrome b-566 heme groups. Alternatively, these effects may reflect changes at the Qp and Qn quinone/quinol binding sites. (5) An unexplained observation for the mutant is the increased rate of cytochrome c1 reduction in the presence of myxothiazol. (6) These functional alterations in the LA9 HQN-R11 mutant are not accompanied by detectable changes in the spectral properties of the cytochrome b or c1 heme groups.