Production of cellulolytic and xylanolytic enzymes during growth of the anaerobic fungus Piromyces sp. on different substrates

Abstract

Piromyces sp. strain E2, an anaerobic fungus isolated from an Indian elephant (hindgut fermenter) was tested for its ability to ferment a range of substrates. The fungus was able to use bagasse, cellobiose, cellulose, fructose, glucose, lactose, mannose, starch, wheat bran, wheat straw, xylan and xylose. Formate and acetate were the main fermentation products after growth on these substrates. The amount of carbon found in the fermentation products of cultures, in which substrate digestion was complete averaged 88.5 mM, or 59% of the carbon offered as substrate. No growth was observed on other substrates tested. Lactose, starch, cellobiose and filter paper cellulose were good inducers of cellulolytic and xylanolytic enzymes. Cellulolytic and xylanolytic enzymes were produced constitutively by Piromyces strain E2, although enzyme activities were generally lower after growth on glucose and other soluble sugars. Complex substrates (bagasse, wheat bran, and wheat straw) were good inducers for xylanolytic enzymes but not for cellulolytic enzymes. The extracellular protein banding pattern after SDS-PAGE was therefore only slightly affected by the growth substrate. Identical P-glucosidase and endoglucanase activity patterns were found after growth on different substrates. This indicated that differences in enzyme activities were not the result of secretion of different sets of isoenzymes although it remains possible that the relative amount of each isoenzymp produced is influenced by the growth substrate.

Fibrolytic potential of anaerobic fungi (Piromycessp.) isolated from wild cattle and blue bulls in pure culture and effect of their addition onin vitrofermentation of wheat straw and methane emission by rumen fluid of buffaloes

“…The ranges of enzyme levels of Piromyces sp. of anaerobic fungi reported previously by others,33–36 utilising similar methods of enzyme production, harvesting and assay as used in the present study and using straw as substrate for enzyme production, were 0–36 mIU mL −1 for CMCase, 0.6–15 mIU mL −1 for MCCase and 0–10 mIU mL −1 for β‐glucosidase. Our estimated values for MCCase, acetyl esterase and xylanase were comparable to values reported previously, while our values for CMCase for most of the isolates were considerably higher than values reported previously.…”

Community structure and fibrolytic activities of anaerobic rumen fungi in dromedary camels

“…Anaerobic rumen fungi have high cellulolytic and xylanolytic activities . Cellulase production in our study is similar to the production of anaerobic rumen fungi grown on a range of soluble and insoluble substrates . Cyllamyces and Piromyces are capable of fermenting fibrous substrates and have xylanolytic and cellulolytic activity .…”

Effect of the carbohydrate growth substrate on polysaccharolytic enzyme formation by anaerobic fungi isolated from the foregut and hindgut of nonruminant herbivores and the forestomach of ruminants

“…(Williams and Orpin 1987a,b;Morrison et al 1990) is catabolite regulated. The extracellular activities of xylanase, CMCase and fl-glucosidase in culture supernatants of a Piromyces strain isolated from an Asian elephant were also reduced after growth on glucose and other soluble substrates but only minor differences were found in the banding patterns of the extracellular proteins after cultivation on different substrates, indicating that enzyme formation was constitutive (Teunissen et al 1992). Conversely the banding patterns of the extracellular proteins were substrate-dependent and indicative of positive control in a ruminal N .…”

“…Extracellular enzyme formation by Piromyces sp. strain E2 was subsequently shown to be constitutive on a range of soluble and complex substrates (Teunissen et al 1992). This study was undertaken to examine the formation of polysaccharide-degrading enzymes by anaerobic fungi isolated from seven nonruminant and two ruminant hosts, and to evaluate the effects of the carbohydrate growth substrate on enzyme formation.…”