Breakdown Of Pectin Research Articles

A time course analysis of the extracellular proteome of Aspergillus nidulans growing on sorghum stover

BackgroundFungi are important players in the turnover of plant biomass because they produce a broad range of degradative enzymes. Aspergillus nidulans, a well-studied saprophyte and close homologue to industrially important species such as A. niger and A. oryzae, was selected for this study.ResultsA. nidulans was grown on sorghum stover under solid-state culture conditions for 1, 2, 3, 5, 7 and 14 days. Based on analysis of chitin content, A. nidulans grew to be 4-5% of the total biomass in the culture after 2 days and then maintained a steady state of 4% of the total biomass for the next 12 days. A hyphal mat developed on the surface of the sorghum by day one and as seen by scanning electron microscopy the hyphae enmeshed the sorghum particles by day 5. After 14 days hyphae had penetrated the entire sorghum slurry. Analysis (1-D PAGE LC-MS/MS) of the secretome of A. nidulans, and analysis of the breakdown products from the sorghum stover showed a wide range of enzymes secreted. A total of 294 extracellular proteins were identified with hemicellulases, cellulases, polygalacturonases, chitinases, esterases and lipases predominating the secretome. Time course analysis revealed a total of 196, 166, 172 and 182 proteins on day 1, 3, 7 and 14 respectively. The fungus used 20% of the xylan and cellulose by day 7 and 30% by day 14. Cellobiose dehydrogenase, feruloyl esterases, and CAZy family 61 endoglucanases, all of which are thought to reduce the recalcitrance of biomass to hydrolysis, were found in high abundance.ConclusionsOur results show that A. nidulans secretes a wide array of enzymes to degrade the major polysaccharides and lipids (but probably not lignin) by 1 day of growth on sorghum. The data suggests simultaneous breakdown of hemicellulose, cellulose and pectin. Despite secretion of most of the enzymes on day 1, changes in the relative abundances of enzymes over the time course indicates that the set of enzymes secreted is tailored to the specific substrates available. Our findings reveal that A. nidulans is capable of degrading the major polysaccharides in sorghum without any chemical pre-treatment.

Gluconacetobacter hansenii UAC09-mediated transformation of polyphenols and pectin of coffee cherry husk extract

Gluconacetobacter, a bacterial cellulose (BC)-producing organism, has ability to utilise pectin and phenolic compounds. The extract of coffee cherry husk (CCH), a high pectin- and polyphenol-containing agro waste was used in the study. Production of endo- and exo-polygalacturonase, polyphenol oxidase and tannase was observed during fermentation. Co-utilisation of glucose and galacturonic acid was observed. Accumulation of rhamnose, arabinose and galactose indicated the breakdown of pectin. Among the phenolic acids, benzoic acid derivatives were found to be degraded faster than cinnamic acid derivatives. Degradation of tannic acid was more pronounced among the bound forms than free forms in the culture broth. In BC, accumulation of free tannic, gentisic and coumaric acids was observed during the 2nd week of fermentation. The present work indicates the ability of the organism to produce BC by the utilisation of agro waste like CCH.

Gluconate Metabolism Is Required for Virulence of the Soft-Rot Pathogen Pectobacterium carotovorum

Pectobacterium carotovorum is a ubiquitous soft rot pathogen that uses global virulence regulators to coordinate pathogenesis in response to undefined environmental conditions. We characterize an operon in P. carotovorum required for gluconate metabolism and virulence. The operon contains four genes that are highly conserved among proteobacteria (initially annotated ygbJKLM), one of which was misassigned as a type III secreted effector, (ygbK, originally known as hopAN1). A mutant with a deletion-insertion within this operon is unable to metabolize gluconate, a precursor for the pentose phosphate pathway. The mutant exhibits attenuated growth on the leaves of its host of isolation, potato, and those of Arabidopsis thaliana. Notably, the mutant hypermacerates potato tubers and is deficient in motility. Global virulence regulators that are responsive to cell wall pectin breakdown products and other undefined environmental signals, KdgR and FlhD, respectively, are misregulated in the mutant. The alteration of virulence mediated via changes in transcription of known global virulence regulators in our ygbJ-M operon mutant suggests a role for host-derived catabolic intermediates in P. carotovorum pathogenesis. Thus, we rename this operon in P. carotovorum vguABCD for virulence and gluconate metabolism.

The Glycobiome of the Rumen Bacterium Butyrivibrio proteoclasticus B316T Highlights Adaptation to a Polysaccharide-Rich Environment

Determining the role of rumen microbes and their enzymes in plant polysaccharide breakdown is fundamental to understanding digestion and maximising productivity in ruminant animals. Butyrivibrio proteoclasticus B316T is a Gram-positive, butyrate-forming rumen bacterium with a key role in plant polysaccharide degradation. The 4.4Mb genome consists of 4 replicons; a chromosome, a chromid and two megaplasmids. The chromid is the smallest reported for all bacteria, and the first identified from the phylum Firmicutes. B316 devotes a large proportion of its genome to the breakdown and reassembly of complex polysaccharides and has a highly developed glycobiome when compared to other sequenced bacteria. The secretion of a range of polysaccharide-degrading enzymes which initiate the breakdown of pectin, starch and xylan, a subtilisin family protease active against plant proteins, and diverse intracellular enzymes to break down oligosaccharides constitute the degradative capability of this organism. A prominent feature of the genome is the presence of multiple gene clusters predicted to be involved in polysaccharide biosynthesis. Metabolic reconstruction reveals the absence of an identifiable gene for enolase, a conserved enzyme of the glycolytic pathway. To our knowledge this is the first report of an organism lacking an enolase. Our analysis of the B316 genome shows how one organism can contribute to the multi-organism complex that rapidly breaks down plant material in the rumen. It can be concluded that B316, and similar organisms with broad polysaccharide-degrading capability, are well suited to being early colonizers and degraders of plant polysaccharides in the rumen environment.

Degradation of forage chicory by ruminal fibrolytic bacteria.

Determine the susceptibility of forage chicory (Cichorium intybus L.) to degradation by ruminal fibrolytic bacteria and measure the effects on cell-wall pectic polysaccharides. Large segments of fresh forage chicory were degraded in vitro by Lachnospira multiparus and Fibrobacter succinogenes, but not by Ruminococcus flavefaciens or Butyrivibrio hungatei. Cell-wall pectins were degraded extensively (95%) and rapidly by L. multiparus with a simultaneous release of uronic acids and the pectin-derived neutral monosaccharides arabinose, galactose and rhamnose. Fibrobacter succinogenes also degraded cell-wall pectins extensively, but at a slower rate than L. multiparus. Immunofluorescence microscopy using monoclonal antibodies revealed that, after incubation, homogalacturonans with both low and high degrees of methyl esterification were almost completely lost from walls of all cell types and from the middle lamella between cells. Only two of the four ruminal bacteria with pectinolytic activity degraded fresh chicory leaves, and each showed a different pattern of pectin breakdown. Degradation was greatest for F. succinogenes which also had cellulolytic activity. The finding of extensive removal of pectic polysaccharides from the middle lamella and the consequent decrease in particle size may explain the decreased rumination and the increased intake observed in ruminants grazing forage chicory.

An Effective Combination of Carbohydrases That Enables Reduction of Dietary Protein in Broilers: Importance of Hemicellulase

After observing the effects of purified cellulase (C), hemicellulase (H), pectinase (P), and their combinations on the in vitro digestibility of a corn-soybean meal broiler diet, we examined the associations between pectin breakdown and the digestibilities of CP and DM by using free galacturonic acid (GA) as an index of pectin breakdown. There was no significant effect of the single enzymes except for H. However, the enzyme combinations H + P, C + H, and C + H + P significantly increased CP and DM digestibilities, whereas the combination of C + P was not effective. Because H has activities of both H and P, these enzymes were considered to be important in stimulating digestion. Furthermore, when the enzymes increased CP and DM digestibilities, GA concentration was significantly higher, and clear correlations between CP and DM digestibilities and GA concentration were observed, whereas correlations between the digestibilities and concentration of glucose or xylose + mannose as indices of cellulose and hemicellulose breakdown, respectively, were not significant. From these observations, we hypothesized that a mixture of enzymes could increase the protein digestibility of broiler feed. Thus, in the in vivo experiment, low-protein (19% CP) diets made mainly of corn and soybean meal with or without mixed enzymes were prepared and given to broiler chicks. The birds given the diet containing mixed enzymes showed significantly higher BW gain, with higher CP and DM digestibilities than the birds given the diet without the mixed enzymes. Moreover, the growth rate was same as that of the birds given the normal (21% CP) diet. The results indicate that the mixed enzyme preparation can effectively degrade indigestible cell constituents and thus enable the protein of the broiler feed to become more digestible. Furthermore, the results indicate the importance of H as a rate-limiting factor of cell wall breakdown.

Enzyme activities and pectin breakdown of sapodilla submitted to 1-methylcyclopropene

The objective of this work was to investigate the influence of 1-methylcyclopropene (1-MCP) at 300 nL L-1 on activities of cell wall hidrolytic enzymes and pectin breakdown changes which Sapodilla (Manilkara zapota cv. Itapirema 31) cell wall undergoes during ripening. Sapodilla were treated with ethylene antagonist 1-MCP at 300 nL L-1 for 12 hours and then, stored under a modified atmosphere at 25º C for 23 days. Firmness, total and soluble pectin and cell wall enzymes were monitored during storage. 1-MCP at 300 nL L-1 for 12 hours delayed significantly softening of sapodilla for 11 days at 25º C. 1-MCP postharvest treatment affected the activities of cell wall degrading enzymes pectinmethylesterase and polygalacturonase and completely suppressed increases in beta-galactosidase for 8 days, resulting in less pectin solubilization. Beta-galactosidase seems relevant to softening of sapodilla and is probably responsible for modification of both pectin and xyloglucan-cellulose microfibril network.

THE EFFECT OF PROCESSING METHOD ON THE CHARACTERISTICS OF CARROT JUICE

ABSTRACT The production of carrot juice using different technologies is the main subject of this investigation. Although the production and preservation of the carrot juice technology have not been improved and are not prevalent, an intensive study has been carried out on this subject recently. In this study, the effects on the yield and quality of carrot juice produced with and without total enzymatic liquefaction (Pectinex Ultra SP‐L, Novo Nordisk Ferment, Dittingen, Switzerland) as well as lactofermentation or citric acid addition have been investigated. Generally, enzymatic liquefaction of mash increased the juice yield (89.32 ± 1.17 and 90.43 ± 0.47% for lactofermented and citric‐acid‐added samples, respectively), while the control sample juice yield was found to be 59.90 ± 0.81%. Lactofermented and acid‐added samples demonstrated lower pH value. In enzyme‐treated samples, the total acidity increments were also determined. Accordingly, galacturonic acid formed after enzymatic breakdown of pectin in the raw material increased the total acidity of the samples. Magnesium contents of lactofermented juices were found to be low because lactic acid bacteria require magnesium for their growth. β‐Carotene contents have been found to be higher in both lactofermented and in nonenzyme‐treated samples.PRACTICAL APPLICATIONSThis article describes the effects of different processing methods on the characteristics of carrot juice. It is difficult to preserve vegetable juices such as carrot juice because of their low acidity. The acidity of carrot juice (pH ∼6.2) can be adjusted by the addition of citric acid or the lactofermentation method to pH 4.5. With these processes carrot juice can be preserved by pasteurization as occurs for low pH fruit juices, increasing shelf life. According to the results of this study, increasing the acidity of mash with lactofermentation or citric acid addition also increases the juice yield.

Physiological and biochemical changes during banana ripening and finger drop

Fruit drop of banana is due to breaking at the junction of the pedicel and pulp, and we found no true abscission zone. The breakage seems therefore due to weakening of the peel. We investigated pectin hydrolysis and some properties at the rupture zone, using ‘Hom Thong’ ( Musa acuminata, AAA Group) and ‘Namwa’ ( Musa x paradisiaca, ABB Group) fruit, which show massive drop and no drop, respectively. During the period of finger drop, the water content of the peel in ‘Namwa’ was similar to that of ‘Hom Thong’ and thus water content does not account for the high breakage in ‘Hom Thong’. The peel thickness at the rupture area in the two cultivars was not significantly different. During the period of finger drop, the level of water-soluble pectin in the peel at the rupture area of ‘Hom Thong’ was higher than that of ‘Namwa’, indicating pectin degradation. CDTA soluble pectin and insoluble pectin was lower in ‘Hom Thong’, also indicating more pectin breakdown in this cultivar. Polygalacturonase activity in the peel at the rupture area of ‘Hom Thong’ bananas rapidly increased, but not clearly more than in ‘Namwa’ bananas. Pectinesterase activity in the peel at the rupture area of ‘Hom Thong’ was much lower than that of ‘Namwa’ bananas, and thus does not account for the breakage. Pectate lyase in the peel of ‘Hom Thong’ was considerably higher than in that of ‘Namwa’. The present data indicate that the much higher pectate lyase activity in ‘Hom Thong’ might be responsible, at least partially, for the finger drop.

Determination of pathogen-related enzyme action by mass spectrometry analysis of pectin breakdown products of plant cell walls

An analytical approach using matrix-assisted laser desorption/ionization mass spectrometry for the structural characterization and assessment of the degree of polymerization of cell wall pectin-derived oligosaccharides (PDOs) in three regions of Botrytis cinerea-infected tomato fruit tissue is described. The PDOs were isolated from lesion centers (extensively macerated tissue), the area just beyond visible lesion margins, and healthy and intact tissue of an inoculated fruit, sampled at a distance from developing lesions. PDO mixtures were directly analyzed by mass spectrometry without chromatographic separation, after minimum cleanup by membrane drop dialysis. The structures identified implied the action of three different pathogen pectin-modifying enzymes. Modifications such as methyl esterification were identified by determination of exact PDO molecular masses and tandem mass spectrometry via collision-induced dissociation. We have identified four PDO series that were generated through the breakdown of homogalacturonan pectins. The decayed and lesion edge areas had fewer and less diverse PDOs than healthy tissues, possibly due to metabolic by-products of the pathogen. This analytical technique provides a simple and rapid method to characterize the pectin-derived oligosaccharides produced by in vivo digestion during pathogen infection.

Effects of storage on quality of carrot juices produced with lactofermentation and acidification

In this study, effects on the yield and the quality of product properties of carrot juice produced with lactofermentation and added citric acid, and with and without total enzymatic liquefaction (Pectinex Ultra SP-L) were investigated. Samples were stored at room temperature for 6 months and analytical changes which might occur were determined at day 0 and after 2, 4 and 6 months by quality control tests. In enzyme-treated samples, the yield and the quality of mineral incrementation were determined. Accordingly, ash and water-soluble dry matter contents were increased in the samples. Galacturonic acid formed after enzymatic breakdown of pectin in the raw material increased the total acidity of the samples. Sensorial tests of the product were also carried out. According to the test results, the products produced with enzyme treatment at day 0, after 2 and 4 months storages were found to be the ones mostly preferred. However the samples without enzyme treatment were preferred by the panelists after long-term (6 months) storage.

HPAEC–PAD analysis of oligogalacturonic acids in strawberry juice

High performance anion-exchange chromatography (HPAEC), coupled with pulsed amperometric detection (PAD), was used to identify and quantify oligogalacturonic acids (OGAs) in strawberry juice. This method allowed good separation and detection of OGAs with degree of polymerization (DP) <20 units, and has proved to be a useful tool for the study of the chemical composition of pectin breakdown products. However, the lack of availability of OGA standards above 3 DP units limited the quantification for these compounds. Treatment of strawberry juice with seven commercial pectolytic enzymes was investigated. Glucuronic acid occurred in strawberry only in small amounts (12±0.5 mg/l) and its concentration was not affected by the enzymatic treatment. Polygalacturonic acid can be hydrolyzed in several ways, yielding different sets of oligomeric degradation products depending on the hydrolysis conditions. The use of Rohament ® MAX enzyme, for 2 h at 45°C, produced juice with by far the highest concentration of OGAs. Moreover, treatment with Grindamyl Pectinase ™ LM was also extended to 4 and 6 h to measure the time course of pectinase activity and verify the stability of OGA. This enzyme generated high levels of pectin breakdown products proportionately with time (monitored up to 6 h) and increased the total level of OGAs with DP ⩾4 units from 78 to 771 mg/l. ©

Polygalacturonase-mediated solubilization and depolymerization of pectic polymers in tomato fruit cell walls . Regulation By ph and ionic conditions

The hydrolysis of cell wall pectins by tomato (Lycopersicon esculentum) polygalacturonase (PG) in vitro is more extensive than the degradation affecting these polymers during ripening. We examined the hydrolysis of polygalacturonic acid and cell walls by PG isozyme 2 (PG2) under conditions widely adopted in the literature (pH 4.5 and containing Na+) and under conditions approximating the apoplastic environment of tomato fruit (pH 6.0 and K+ as the predominate cation). The pH optima for PG2 in the presence of K+ were 1.5 and 0.5 units higher for the hydrolysis of polygalacturonic acid and cell walls, respectively, compared with activity in the presence of Na+. Increasing K+ concentration stimulated pectin solubilization at pH 4.5 but had little influence at pH 6.0. Pectin depolymerization by PG2 was extensive at pH values from 4.0 to 5.0 and was further enhanced at high K+ levels. Oligomers were abundant products in in vitro reactions at pH 4.0 to 5.0, decreased sharply at pH 5.5, and were negligible at pH 6.0. EDTA stimulated PG-mediated pectin solubilization at pH 6.0 but did not promote oligomer production. Ca2+ suppressed PG-mediated pectin release at pH 4.5 yet had minimal influence on the proportional recovery of oligomers. Extensive pectin breakdown in processed tomato might be explained in part by cation- and low-pH-induced stimulation of PG and other wall-associated enzymes.

Ultrastructural and cytochemical studies of cucumber roots infected by two Pythiumspecies with different modes of pathogenicity

Two Pythiumspecies showing different patterns of pathogenicity, PythiumF and Pythium aphanidermatum, were inoculated into the roots of Cucumis sativusand their processes of infection investigated and compared. PythiumF, a ubiquitous minor pathogen of cucumber in soilless cultures, induces marked damage to the epidermal and cortical tissues but it never penetrated further than the endodermis. Host cell wall labelling with specific gold-complex probes (AGL-and exoglucanase-gold complexes) revealed pectin breakdown and cellulose alterations which were mainly restricted to sites of fungal penetration. Invasion was also associated with striking host cell reactions, including the formation of papillae, and wall appositions lining the host cell walls. These newly-formed materials were highly heterogeneous with respect to chemical composition as judged by the differential labelling obtained with an exoglucanase probe and with an RcA gold complex used to localize galactose molecules. Plugging of the intercellular spaces in the cortex with an electron opaque material, presumably enriched with phenolic compounds, was also frequently observed. Some cortical cells were also completely filled with opaque flecks of amorphous or osmiophilic material and PythiumF hyphae growing in such occluded cells were often moribund. Inoculation of cucumber roots with P. aphanidermatumresulted in a rapid and massive colonization of all root tissues, including those of the stele. Pathogen ingress was associated with extensive host cell alterations with cellulose and pectin breakdown occurring at a distance from the fungus. The main host reaction was the occlusion of parenchyma cells in the stele and cortex with an amorphous material but the deposition of this material appeared to occur too late to be effective in blocking P. aphanidermatumattack. Other host reactions were seldom observed in P. aphanidermatuminfected roots.

Inhibition of Polygalacturonase in Tomato Pericarp Tissue by Lysophosphatidylethanolamine: Implications in Fruit Shelf-life

The pericarp tissue of red mature tomato (Lycopersicon esculentum cv. Gagliano) was used to exctract polygalacturonase (PG) enzyme. The technique for assaying PG activity involves measurement of released reducing groups that were linked together in pectin. Since the crude extract of PG from pericarp will contain considerable reducing groups, we found that repeated washings of the cell wall pulp removed much of the sugars and thus minimized the background absorbance without loss of PG activity. There is an inherent perplexity concerning the selection of blank for PG assay. This is because (i) the enzyme extract contains both the substrate (pectin) and product (free reducing groups) involved in the reaction; (ii) the color development with cyanoacetamide requires heating for 10 min. Thus, even though the reaction is terminated with borate buffer (pH 9.0) the breakdown of pectin continues chemically by heat; (iii) the absorbance from both pectin and enzyme together at zero time termination was always lower than the sum of absorbances from pectin alone and enzyme alone. This suggests that when together in the same tube, the enzyme appears to protect the pectin from physical breakdown during the period of 10 min. boil needed to develop color using the cyanoacetamide. Thus, the most appropriate blank is processing separately the solutions of enzyme alone and substrate pectin alone for color development and then adding the two absorbances. Using this improved assay we found that lysophosphatidylethanolamine (LPE) inhibited tomato PG activity. This inhibition appears to depend on the ripening stage of the fruit. Our results suggest that LPE is able to impart firmness to tomato fruit by reducing the PG activity, which in turn could protect the pectin/middle lamellae from enzymic breakdown. The effects of LPE on PG activity are distinct from those of Triton X-100 and lysophosphatidylcholine.

Comparison of the cooking behaviour of the potato cultivars Nicola and Irene with respect to pectin breakdown and the transfer of ions

The potato cultivars Nicola and Irene were investigated with respect to cell sloughing, specific cell surface area, release of pectic material and transfer of ions using a model cooking study. Both cell sloughing and the release of pectic material were higher for the mealy-cooking cultivar Irene. As the respective cell size distributions measured were the same for both cultivars, the difference in release of pectic material could not be explained by a difference in the specific cell surface areas between the cultivars. Additionally, it was recorded that during cooking only 20% of the calcium present in non-cooked tissue was transferred into the cooking medium, whereas more than 70% of potassium and citrate were transferred. The ratios Da.citr2−/Da.K+ and Da.Ca2+/Da.K+ for water and cooked potato tissue revealed that in water, potassium ions diffused faster than citrate and calcium ions. However, in cooked potato tissue both citrate and calcium ions diffused faster than potassium ions.

A Polygalacturonase Gene from Kiwifruit (Actinidia deliciosa)

has been the subject of considerable study in tomato (reviewed by Fischer and Bennett, 1991). The enzyme is expressed to a high leve1 late in fruit ripening, when it is involved in the breakdown of pectin, a major component of the middle lamella. Wegrzyn and MacRae (1992) recently reported

Pectin degradation during root decay of rubber trees by Rigidoporus lignosus

Aplysia gonad lectin, which binds polygalacturonic acid, was complexed to colloidal gold and used for localizing molecules that contain polygalacturonic acid in rubber tree roots infected with the white-rot root fungus Rigidoporus lignosus. Colonization of root tissues was associated with strong wall alteration of phloem cells and with degradation of the compound middle lamella in both the phloem (10 weeks after inoculation) and the xylem (15 weeks after inoculation). Our data suggest that pectin breakdown during root decay likely occurs after cellulose and lignin breakdown and may result from the fungal pectinase activities that were detected in vitro. Released pectin oligomers may act as inducers of both fungal laccase and of the tree defense system during root invasion. Key words: root rotting fungi, rubber, pectin, cellulose, cytochemistry.

Isolation and spectral characterization of plant-cuticle polyesters

An efficient protocol combining enzymatic and chemical methods has been developed for the isolation of lime fruit cutin and potato suberin in pure form and with excellent yields. Starting with the procedures specified by commercial assay kits for model substrates, the breakdown of cellulose, pectin, and hemicellulose cell-wall constituents was optimized with respect to enzyme concentration, substrate concentration, reaction time, and temperature. The optimized procedures were then applied to the plant polyesters cutin and suberin, with the isolation process monitored in parallel by gravimetric methods and with cross-polarization magic-angle spinning 13 C NMR

The flows of deoxyribonucleic acid and diaminopimelic acid and the digestibility of dietary fibre components at the terminal ileum, as indicators of microbial activity in the upper digestive tract of ileostomised pigs

The microbial markers deoxyribonucleic acid (DNA) and diaminopimelic acid (DAP) were used to compare the microbial biomass in the ileal digesta of ileostomised pigs with that in the faeces of intact pigs. Ileal and faecal (whole tract) digestibility of dietary fibre was also determined, to indicate the extent of microbial activity in the upper and lower digestive tracts. Six ileostomised pigs of 25 kg live weight and six intact pigs were given a human-type diet of bread, raw and cooked vegetable, cooked meat and dairy products for 12 days, total ileal digesta or faeces being collected over the final 4 days. The mean excretion of DNA in the ileal digesta (100.4 mg day −1) was significantly ( P < 0.01) greater than that in the faeces (48.2 mg day −1), while the mean ileal and faecal excretions of DAP (56.7 mg day −1 and 62.8 mg day −1, respectively) were not significantly different. On the basis of the mean DAP concentrations, the estimated concentrations of bacterial dry matter in ileal or faecal dry matter were 208 mg g −1 and 694 mg g −1, respectively. The digestibility of the dietary fibre components was significantly ( P < 0.001) greater when measured over the entire digestive tract than at the terminal ileum, though there was a considerable breakdown of pectin, hemicellulose and cellulose anterior to the end of the small intestine. It was concluded that there is a substantial and active microflora in the upper digestive tract of ileostomised pigs, and this may have implications for the determination of nutrient digestibility with surgically modified animals.