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PubMed1988

Rates of digestion of bacteria by marine phagotrophic protozoa: temperature dependence.

The effect of temperature on length of time for digestion of bacteria was evaluated, by using fluorescently labeled bacteria (FLB), for phagotrophic flagellates and ciliates isolated from coastal northwest Mediterranean waters. Accumulation of FLB in protozoan food vacuoles was followed until a plateau of FLB per cell occurred; then after a 1:10 dilution of FLB with unlabeled bacteria, disappearance of FLB in food vacuoles was monitored. For both 3- to 5-mum flagellates and 10- to 40-mum ciliates, the absolute linear slopes of FLB uptake and disappearance were nearly identical in individual experiments over a temperature range of 12 to 22 degrees C. We inferred from these results that the leveling off of the uptake curves resulted when equilibrium between ingestion and digestion of bacteria was attained. The time to leveling off then represented the average time needed for complete digestion of the bacteria ingested at the start of the experiment, and the inverse of this time represented a bacterial digestion rate. The digestion rate increased exponentially from 12 to 22 degrees C for both a mixed flagellate assemblage and the oligotrichous ciliate Strombidium sulcatum, with a Q(10) of 2.8 for the flagellates and 2.0 for the ciliate. Although bacterial ingestion rates varied greatly, depending on protozoan cell size, total bacterial abundance, and temperature, digestion times appeared to be significantly influenced only by protozoan cell size (or type of protozoan) and by temperature.

Journal Article↗
PubMed1988

Production and Characteristics of Raw-Potato-Starch-Digesting alpha-Amylase from Bacillus subtilis 65.

A newly isolated bacterium, identified as Bacillus subtilis 65, was found to produce raw-starch-digesting alpha-amylase. The electrophoretically homogeneous preparation of enzyme (molecular weight, 68,000) digested and solubilized raw corn starch to glucose and maltose with small amounts of maltooligosaccharides ranging from maltotriose to maltoheptaose. This enzyme was different from other amylases and could digest raw potato starch almost as fast as it could corn starch, but it showed no adsorbability onto any kind of raw starch at any pH. The mixed preparation with Endomycopsis glucoamylase synergistically digested raw potato starch to glucose at 30 degrees C. The raw-potato-starch-digesting alpha-amylase showed strong digestibility to small substrates, which hydrolyzed maltotriose to maltose and glucose, and hydrolyzed p-nitrophenyl maltoside to p-nitrophenol and maltose, which is different from the capability of bacterial liquefying alpha-amylase.

Journal Article↗
PubMed1990

Differential rates of digestion of bacteria by freshwater and marine phagotrophic protozoa.

Differential decreases over time of two bacterial species, Escherichia coli and Enterococcus faecalis, in a freshwater and a marine ecosystem were observed and explained by a differential rate of digestion of these bacteria by phagotrophic flagellates and ciliates. For this purpose, fluorescence-labeled bacteria (FLB) were used and prepared from the two species cited above. The number of FLB was observed for 5 days in fresh and marine waters in the presence or absence (0.2-mum-pore-size-filtered water) of natural microbiota. These experiments showed a longer persistence of Enterococcus faecalis FLB as opposed to Escherichia coli FLB in the presence of natural microbiota. Removal of FLB was due to protozoan grazing because no decrease of FLB number was observed in the absence of natural microbiota. In short-term (about 40 min) ingestion experiments, we found similar clearance rates of Escherichia coli and Enterococcus faecalis FLB by assemblages of flagellates from the freshwater and the marine ecosystem and by cultured assemblages of ciliates from the marine ecosystem. Clearance rates of Enterococcus faecalis FLB were greater than those of Escherichia coli FLB for assemblages of ciliates from the freshwater ecosystem. Comparison of rates of ingestion and digestion of FLB by protozoa showed that Escherichia coli FLB were digested and ingested at similar rates. However, Enterococcus faecalis FLB were digested slower than they were ingested. These results suggest that a longer persistence of Enterococcus faecalis as opposed to Escherichia coli can be explained by a differential digestion by flagellates and ciliates in aquatic ecosystems. Moreover, rates of ingestion and digestion were strongly correlated for both FLB types.

Journal Article↗
PubMed1983

Digestion of proteoglycan by Bacteroides thetaiotaomicron.

It has been shown previously that Bacteroides thetaiotaomicron, a human colonic anaerobe, can utilize the tissue mucopolysaccharide chondroitin sulfate as a source of carbon and energy and that the enzymes involved in this utilization are all cell associated (A. A. Salyers and M. B. O'Brien, J. Bacteriol. 143:772-780, 1980). Since chondroitin sulfate does not generally occur in isolated form in tissue, but rather is bound covalently in proteoglycan, we investigated the extent to which chondroitin sulfate which is bound in such a sterically hindered complex can be utilized by intact bacteria. Intact cells of B. thetaiotaomicron were able to digest chondroitin sulfate in proteoglycan, although at a slightly slower rate than free chondroitin sulfate. Prior digestion of proteoglycan with trypsin to produce small fragments of protein with several chondroitin sulfate chains attached did not increase the rate at which the bound chondroitin sulfate was digested. Accordingly, the slower rate of digestion was probably due to attachment of chondroitin sulfate chains to the protein backbone rather than to steric hindrance by other components of the proteoglycan. When proteoglycan which had been incubated with intact bacteria was treated with sodium borohydride to release the undigested fragments of chondroitin sulfate from the protein backbone, the size and composition of the fragments indicated that intact bacteria were able to digest all but three monosaccharides of the chondroitin sulfate chains. Thus, despite steric hindrance due to attachment of the chondroitin sulfate chains to the protein backbone, digestion of bound chondroitin sulfate by intact bacteria was nearly complete.

Bacteroides↗
PubMed1982

Intracellular forms of simian virus 40 nucleoprotein complexes. IV. Micrococcal nuclease digestion.

The structures of DNAs present in various intracellular forms of simian virus 40 (SV40) nucleoprotein complexes were analyzed by micrococcal nuclease digestion. The results showed that the 70S SV40 chromatin was completely sensitive to nuclease digestion, whereas CsCl gradient-purified mature virion was completely resistant. Virion assembly intermediates with different degrees of virion maturation showed intermediate resistance, and three products were found: nucleosomal DNA fragments, representing the fraction of intermediates that were sensitive to nuclease; linear SV40 genome-sized DNA, representing the more mature intermediates that contained one or limited defects in the capsid shell; and supercoiled SV40, which was derived from mature virions. These digestion products, however, remained associated with capsid shells after nuclease digestion. These results were consistent with the model in which maturation of the SV40 virion is achieved through the organization of capsid proteins that accumulate around SV40 chromatin. Mild digestion of SV40 nucleoprotein complexes with micrococcal nuclease revealed the difference in nucleosome repeat length between SV40 chromatin and virion assembly intermediates. A novel DNA fragment of about 75 nucleotides was observed early in nuclease digestion.

Animals↗
PubMed2000

Resistance of native, oligomeric envelope on simian immunodeficiency virus to digestion by glycosidases.

Stocks of simian immunodeficiency virus (SIV) from the supernatants of infected cell cultures were used to examine the sensitivity of envelope glycoprotein gp120 to enzymatic deglycosylation and the effects of enzyme treatment on infectivity. Sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis and Western blot analysis revealed little or no change in the mobility of virion-associated gp120 after digestion with high concentrations of N-glycosidase F, endoglycosidase F, endoglycosidase H, and endo-beta-galactosidase. Soluble gp120, which was not pelletable after the enzymatic reaction, was sensitive to digestion by the same enzymes within the same reaction mix and was only slightly less sensitive than gp120 that had been completely denatured by boiling in the presence of SDS and beta-mercaptoethanol. Digestion by three of the seven glycosidases tested significantly changed the infectivity titer compared to that of mock-treated virus. Digestion by endo-beta-galactosidase increased infectivity titers by about 2.5-fold, and neuraminidase from Newcastle disease virus typically increased infectivity titers by 8-fold. Most or all of the increase in infectivity titer resulting from treatment with neuraminidase could be accounted for by effects on the virus, not the cells; SIV produced in the presence of the sialic acid analog 2,3-dehydro-2-deoxy-N-acetylneuraminic acid also exhibited increased infectivity, and the effects could not be duplicated by neuraminidase treatment of cells. Digestion with mannosidase reduced infectivity by fivefold. Our results indicate that carbohydrates on native oligomeric gp120 as it exists on the surface of virus particles are largely occluded and are refractory to digestion by glycosidases. Furthermore, the sialic acid residues at the ends of carbohydrate side chains significantly reduce the inherent infectivity of SIV.

Animals↗
PubMed1995

Microbial ecology of simultaneous thermophilic microbial leaching and digestion of sewage sludge.

The microbial population encountered during a simultaneous thermophilic microbial leaching and digestion process at 50 degrees C, based on microbial sulfur oxidation, was investigated. The cell count of the sulfuric acid producer Thiobacillus thermosulfatus increased, followed by a decrease. In the absence of sulfur (control: conventional thermophilic digestion), Thiobacillus thermosulfatus population decreased under the detection limit. Acidophilic and neutrophilic heterotrophic populations increased during the leaching process, and the final acidophilic population count was higher than the neutrophilic population. During the thermophilic digestion (control), the final neutrophilic population count was higher than the acidophilic. Six heterotrophic bacterial strains were isolated and partially characterized. Bacillus was the most predominant genus. The type of bacterial populations in thermophilic microbial leaching and digestion, as well as the thermophilic digestion process (control), were the same, while only the relative concentrations changed. In both processes, the bacterial indicators decreased under the detection limit after 12 h. Mesophilic heterotrophic population was more affected by the thermophilic microbial leaching process than by thermophilic digestion. Sludge mineralization was probably more influenced by the final cell concentration rather than the presence of an individual species or mixed population.

Bacteria↗
PubMed2006

Impact of concentration, temperature, and pH on inactivation of Salmonella spp. by volatile fatty acids in anaerobic digestion.

It is known that the presence of volatile fatty acids may play a role in the inactivation of pathogens for systems that employ an acid phase reactor. This study was conducted to investigate the influence of volatile fatty acids on the inactivation of Salmonella spp. over a range of digestion temperatures. In this study, digesters that were treating municipal wastewater treatment plant sludges were operated at temperatures that ranged from 35 to 49 degrees C and had a solids residence time of 15 days. Samples collected from the effluent of the digesters were dosed with solutions containing acetic, propionic, and butyric acids alone and in mixtures, and the dosed effluents were analyzed for Salmonella spp. over time. In the first round of testing, the digester effluents were dosed with individual organic acids and also a mixture containing all three volatile fatty acids over a range of concentrations from 750 to 6000 mg/L, and the pH of the samples was fixed at a value of 5.5. In the second round of testing, the sample sludges were spiked with a fixed amount of organic acid mixture, and the pH was varied from 4.5 to 7.5. The reduction of Salmonella spp. in digester effluents, when dosed with volatile organic acids, was found to depend on pH, temperature, the chain length of the acids, and the concentration and composition of the acids present. Increases in temperature appeared to increase the inhibitory effects of the volatile organic acids. At mesophilic temperatures, acidic pHs resulted in a greater inhibition of Salmonella spp.; whereas at higher temperatures neutral pHs were found to be more inhibitory. The results suggest that acid phase digesters that operate at elevated temperatures and low pH can achieve substantial reduction of Salmonella spp.

Anaerobiosis↗
PubMed1998

A new microwave acid digestion bomb method for the determination of total fluorine.

A new microwave acid digestion method for total fluorine analysis was compared to the reliable reverse-extraction technique. The commercially available Parr bombs which are compatible with microwave heating were modified for this purpose. The Mann-Whitney statistical test did not show any significant differences (p > 0.05) in the determinations of total fluorine in various samples between the two above-mentioned methods. The microwave method also gave high fluorine recoveries (> 97%) when fluoride was added to different samples. The great advantage of the microwave acid digestion bomb method is that the digestion under pressure is so aggressive that only a few minutes is needed for complete digestion (also of covalently bonded fluorine), which reduces the time for fluorine analysis dramatically, while no loss of fluorine or contamination from extraneous sources could take place during the ashing procedure. The digestion solution was made up of 300 microliter of concentrated nitric acid plus 537 microliter of water. After digestion 675 microliter of approximately 8.5 M sodium hydroxide plus 643 microliter of citrate/TISAB buffer was added resulting in an alkaline solution (pH approximately 12) which was finally adjusted to a pH of approximately 5.3 for fluoride determination.

Acids↗
PubMed1969

Two distinct groups of immunoglobulin A(IgA) revealed by peptic digestion.

Serum IgA M-components, secretory IgA separated from colostrum, and IgA from serum of patients with cirrhosis of the liver were digested with pepsin at pH 4.1. The IgA M-components segregated into two groups on the basis of their relative rates of peptic digestion. Serum and colostral IgA were digested at a total rate intermediate to that of the two groups of IgA myeloma proteins. It appeared, however, that colostral IgA may have been initially more resistant to peptic digestion than serum IgA. The variability in the rate of peptic digestion was not related to electrophoretic mobility, light-chain type, or IgA subclass. Experimental conditions related to enzyme to substrate ratio or to the pH of the reaction mixture did not appear to explain the differences found.These findings indicate that (a) two groups of IgA proteins can be distinguished on the basis of susceptibility to proteolysis with pepsin, and (b) secretory piece confers, at most, only a minor increase in stability to the IgA molecule against the digestive action of pepsin.

Chemical Phenomena↗
PubMedDate not supplied

Hypoosmotic exposure of canine pancreatic digest as a means to purify islet tissue.

The development of more effective means to separate pancreatic islets from the unwanted exocrine tissue would greatly advance the field of clinical islet allotransplantation in the treatment of insulin-dependent diabetes mellitus. Recent experiments with hamster islets have demonstrated a selective destruction of dissociated single exocrine cells when exposed to hypotonic conditions. It was the aim of this study to extend these observations to the canine model with collagenase dissociated pancreatic tissue and to evaluate the treatment's effect on islet function. Pancreases from five mongrel dogs were digested using an automated protocol of intraductal delivery of collagenase, and gentle dissociation. Duplicate samples of pancreatic digest were removed for insulin and amylase determination prior to and immediately following exposure to 50 mOsm/kg salt solution for a period of 30, 60, or 300 s before returning the digest to isoosmotic conditions. The remaining digest was cultured for a period of 48 h at 37 degrees C before the tissue was recombined, washed, and a third sample removed for insulin and amylase. In vitro viability was then assessed using a static incubation assay with insulin content measured using a double-antibody radioimmunoassay, and amylase was determined using a colorimetric assay system. No difference in the insulin or amylase levels between the experimental groups was observed immediately following the hypotonic exposure; however, a significant decrease in the amylase content was observed following the 48-h culture period in digest that had been hypoosmotically exposed for 60 or 300 s compared with the pretreatment group (2.83 +/- 0.41 IU amylase/mg pancreas vs. 1.29 +/- 0.21 and 0.83 +/- 0.12, mean +/- SEM, p < 0.05). Insulin content was also significantly reduced in the 300-s exposure group compared with nontreated controls (3.2 +/- 0.6 mU insulin/mg pancreas vs. 2.0 +/- 0.2). The insulin/ amylase ratio (I/A), a measure of islet and exocrine content, was 1.1 +/- 0.13 following pancreas dissociation and 1.34 +/- 0.21 for control tissue cultured for 48 h. The I/A ratio increased following hypoosmotic exposure to 1.50 +/- 0.31 for tissue exposed for 30 s, 1.77 +/- 0.19 for 60-s exposure, and 2.54 +/- 0.13 for tissue exposed for 300 s (p < 0.05, vs. pretreatment group). In vitro insulin secretion was equivalent with the exception of the tissue exposed for 300 s, which had an increased basal level of insulin resulting in a significantly decreased stimulation index (3.8 +/- 0.5 vs. 8.1 +/- 1.2 for the purified islet control group, p < 0.05). These results suggest that a brief hypotonic exposure to pancreatic digest can alter the insulin/amylase ratio; however, there is a functional impairment on subsequent islet function after a period of in vitro tissue culture.

Animals↗
PubMed1990

Histochemical localization and analysis of blood group-related antigens in human pancreas using immunostaining with monoclonal antibodies and exoglycosidase digestion.

We examined the distribution of blood group-related antigens using an indirect immunoperoxidase method with monoclonal antibodies (MAb) directed to A, B, H, Lewis a (Lea), Lewis b (Leb), Lewis x (Lex), and Lewis y (Ley) antigens and Type 1 precursor chain in human pancreas. Effects of prior digestion with exoglycosidases on MAb stainings were simultaneously investigated. A, B, H, Leb, and Ley antigens were detected in acinar cells and interlobular duct cells but not in centroacinar cells, intercalated duct cells, and islet of Langerhans cells. The expression of these antigens in acinar cells was not dependent on Lewis type and secretor status of the tissue donors, whereas that in interlobular duct cells was strictly dependent on secretor status. The distribution pattern of these antigens in acinar cells was not homogeneous, i.e., cells producing H antigens expressed both Leb and Ley antigens but not A or B antigens, whereas those producing A or B antigens did not secrete Leb and Ley as well as H antigens. Digestion with alpha-N-acetylgalactosaminidase or alpha-galactosidase resulted in the appearance of Leb and Ley antigens as well as H antigen in acinar cells producing A and/or B antigens. Type 1 precursor chain was not detected in pancreatic tissues from secretors but appeared in acinar cells producing H antigen after alpha-L-fucosidase digestion, which also disclosed Lex but not Lea antigen in acinar cells expressing both Leb and Ley. In some non-secretors, MAb against Type 1 precursor chain reacted with acinar cells without enzyme digestion. Although Lea antigen was not detected in acinar cells, it was found in centroacinar cells, intercalated duct cells, and interlobular duct cells from all individuals examined except two Le(a-b-) secretors. After sialidase digestion, Lex antigen appeared in centroacinar and intercalated duct cells from some individuals. Sialidase digestion also elicited reactivity with MAb against Type 1 precursor chain in islet of Langerhans cells from some individuals. These results demonstrate the complexity in the pattern of expression and regulation of blood group-related antigens in different cell types of human pancreas. Such complexity may largely be ascribed to differences in individual genotypes and in gene expression patterns of different cell types.

ABO Blood-Group System↗
PubMed1981

Effect of carboxypeptidase digestion of the human choriogonadotropin molecule on its thyrotropic activity.

Digestion of hCG by a mixture of carboxypeptidases B and Y results in an enzyme dose- and incubation time-dependent increase in its ability to stimulate the adenylate cyclase (AC) of human thyroid membranes. Treated under the same conditions [3 h at 37 C; enzyme to hCG ratio, 0.04 (wt/wt)], partially and highly purified hCG preparations display an increase of about 300% in thyroid AC-stimulating activity, while TSH displays a 30% decrease. In contrast, carboxypeptidase digestion of hCG under these conditions has no significant effect on its activity in the rat testis AC assay. The carboxypeptidase digestion results in cleavage of carboxyl-terminal amino acid residues 142--145 from the hCG beta-subunit; digestion of the hCG alpha-subunit is much less effective, as the carboxy-terminal amino acid residue 92 is removed from only about 13% of the hCG molecules. In accord with the results of amino acid analysis, a slight, if any, decrease in apparent molecular weight is found by gel filtration and polyacrylamide gel electrophoresis. In addition, carboxypeptidase digestion results in antigenic alterations of the molecule, as shown by a flatter slope of the dose-response curve in a hCG RIA and a 70% decrease in potency in a RIA that uses an antiserum to the hCG beta carboxy-terminal peptide. These data demonstrate that partial digestion of the hCG molecule with carboxypeptidase results in an increase in human thyroid AC-stimulating activity, with retention of the rat testis AC-stimulating activity.

Adenylyl Cyclases↗
PubMed1975

Relationship of thyrotropin to exophthalmos-producing substance: formation of an exophthalmos-producing factor by pepsin digestion of mouse pituitary tumor and human thyrotropin preparations.

The present report demonstrates that mouse tumor thyrotropin preprarations have exophthalmogenic activity. In addition it shows that the exophthalmogenic activity of mouse tumor thyrotropin can be increased by partial pepsin digestion, whereas the thyroid stimulating activity of mouse tumor thyrotropin is rapidly destroyed by such treatment. Thus, after 30 min of pepsin digestion, mouse tumor thyrotropin has 130% of its initial exophthalmogenic action but only 10% of its thyroid stimulating activity. Preparations of human thyrotropin are similarly sensitive to partial pepsin digestion, i.e., there is a rapid destruction of thyroid stimulating activity but a very much slower destruction of exophthalmogenic activity. Thus, after 30 min of pepsin digestion, preparations of human thyrotropin retain 80% of their exophthalmogenic activity but only 20-30% of their thyroid stimulating action. Since these results are analogous to those obtained in studies of the partial pepsin digestion of bovine thyrotropin (1), partial pepsin digestion of both purified human and purified mouse tumor thyrotropin preparations should yield an exophthalmogenic fragment of the TSH molecule devoid of thyroid stimulating action.

Animals↗
PubMed1993

Influence of liposomes on tryptic digestion of insulin.

The influence of phosphatidylcholine liposomes on the tryptic digestion of insulin was studied to obtain basic information on the interaction between liposomes and peptides or proteins. Protection of insulin from tryptic digestion by liposomes depended on the encapsulation efficiency and the method of preparation of liposomes. REV (reverse phase evaporation vesicles) were most effective for the protection of insulin from tryptic digestion. Tryptic digestion of insulin was accelerated by negatively-charged liposomes (containing 10% phosphatidylserine, phosphatidylinositol, or phosphatidic acid) or by neutral empty liposomes, this digestion being enhanced by progressively smaller liposome size (from 2 to 0.1 microns) in the case of neutral empty liposomes. These results suggest that this enhancement had occurred on the surface of the empty neutral or negatively-charged liposomes. Positively-charged empty liposomes (containing 10% of stearylamine) weakly suppressed the tryptic digestion of insulin. The size of the positively-charged liposomes increased after the addition of insulin, this size increase suggesting that these liposomes were fused by insulin. Presumably, insulin was protected by the lipids around the insulin molecule after the insulin-induced fusion or aggregation of positively-charged liposomes.

Animals↗
PubMedDate not supplied

The reaction front hypothesis in solid-state digestion: estimation of minimum size of viable seed body.

An alternative mechanism for the anaerobic digestion of a bed of solids was recently proposed. A multizoned reaction front might form around a suitable body of seed material, then advance through the bed, within the solid phase. Such a solid-phase mechanism might coexist with liquid-phase digestion but one or the other of these two parallel mechanisms might generally be dominant. It is envisaged that solid-phase digestion would be favored by the presence of viable seed bodies: single particles of a suitable seed material above a minimum size or equivalent aggregates. A key determinant of the feasibility of this mechanism is expected to be the minimum viable size for a seed body (dmin). This would depend on the thickness of the reaction zones, some of which must initially be accommodated within the seed body. In this article, we present some theoretical estimates of dmin, which indicate a magnitude of 7-700 mm. Such values suggest that solid-phase digestion might be the norm in semi-dry waste digesters. Such digestion might be rare in unseeded landfills but it would appear likely that it could easily be initiated by suitable seeding.

Bacteria, Anaerobic↗
PubMed2006

Will anaerobic digestion of solid waste survive in the future?

Anaerobic digestion has captured a significant share of the European market for the biological treatment of the organic fraction in municipal solid waste. Almost 4 million ton per year in digestion capacity has been installed through the construction of more than 120 full-scale plants. Not all plants have been equally successful, due to poor planning, design or bad operation. This, besides higher than expected investment and operating costs, may have slowed down the growth of anaerobic digestion of solid waste. However, an evaluation of the development of anaerobic digestion over the last 15 years shows that there is now a greater diversity in application, a wider range in types of systems and suppliers, and a continued increasing rate of implementation throughout most parts of Europe. New alternative treatment techniques have not seen the same level of success as anaerobic digestion. Anaerobic digestion has been established as a viable treatment technology for the organic fraction of municipal solid waste and will most likely play an even more important role in the future.

Anaerobiosis↗
PubMed2006

Mesophilic-thermophilic-mesophilic anaerobic digestion of liquid dairy cattle manure.

The potential of a mesophilic-thermophilic-mesophilic anaerobic digestion system was investigated with respect to improvement of both digestion and sanitation efficiencies during treatment of liquid cattle manure. The pilot plant produced a high methane yield from liquid dairy cattle manure of 0.24 m3 (kg VSfed)(-1) Considering the low system loading rate of 1.4-1.5 kg VS (m3 d)(-1), digestion efficiency compared to conventional processes did not appear improved. The minimum guaranteed retention time in the tubular thermophilic reactor was increased compared to a continuously stirred tank reactor. Levels of intestinal enterococci in raw liquid manure as determined with cultivation methods were reduced by 2.5 -3 log units to a level of around 10(2) cfu/mL. This sanitizing effect was achieved both during mesophilic-thermophilic-mesophilic and thermophilic-mesophilic treatment, provided the thermophilic digester was operated at 53-55 degrees C. A change in feeding interval from 1 h to 4 h did not significantly alter methane yield and sanitation efficiency. It was proposed that a two-stage, thermophilic-mesophilic anaerobic digestion system would be able to achieve the same sanitizing effect and equal or better digestion efficiency at lower costs.

Animals↗