Chaetomium Cellulolyticum Research Articles

In-Vitro Screening on the Interaction of Chaetomium Cellulolyticum Chachal & D. Hawksworth with Aspergillus flavus Link Ex Fr. and Curvularia lunata (Wakker) Boedijin

This study generally aimed to determine the interaction of Chaetomium cellulolyticum with Aspergillus flavus and Curvularia lunata and the antifungal properties of Chaetomium cellulolyticum extracts against of Aspergillus flavus and Curvularia lunata. Description of the fungal microscopic association was done in slide bi-culture while the zone of colonization was studied in the co-culture method and zone of inhibition was determined in the antimicrobial bioassay. Results revealed that in slide bi-culture test, the hyphae of A. flavus were damaged when grown together with C. cellulolyticum. Co-culture method revealed that C. cellulolyticum does not colonize the agar lawn of A. flavus. In bioassay, results revealed that at 24 th to 48 th hours of incubation, mycelial crude hexane and ethanol extracts do not produced zone of inhibition on A. flavus. Statistical analysis showed that the zone of inhibition of the two crude extracts were comparable to the positive and negative control. However, at 72 nd to 96 th hours, the extracts were significantly smaller to the positive control and comparable to the negative control (p<0.05). In slide bi-culture test revealed that the hyphae and conidia of C. lunata were broken when grown together with C. cellulolyticum. In Co-culture method results revealed that C. cellulolyticum colonized the agar lawn of C. lunata by 0.15%. In Bioassay, results revealed that mycelial crude hexane and ethanol extracts do not produced zones of inhibition on C. lunata at 24 th to 96 th hours of incubation. Analysis of variance and comparison among means showed, that inhibitions of two extracts were comparable to the positive and negative control at 24 th hours of incubation. However, at 48 th to 96th hours of incubation, the crude extracts were significantly smaller to the positive control but comparable to the negative control (p<0.05). Chaetomium cellulolyticum have antibiosis mechanism to deform or damage the morphological hyphae and either conidia of A. flavus and C. lunata. However, the affectivity of crude hexane and ethanol extracts from C. cellulolyticum were not observed to inhibit the growth of A. flavus and C. lunata.

Improvement of carboxymethyl cellulase production from Chaetomium cellulolyticum NRRL 18756 by mutation and optimization of solid state fermentation

The purpose of the present investigation was to enhance the production of the industrially important enzyme carboxymethyl cellulase (CMCase) by subjecting the wild cellulase producing fungal strain Chaetomium cellulolyticum NRRL 18756 to various doses of gamma irradiation (0.25, 0.5, 0.75, 1.0, 1.25, 1.5, 1.75 and 2.0 KGy). Among all the mutants tested, M-7 obtained at 0.5 KGy of C. cellulolyticum strain showed highest extracellular CMCase production in a yield 1.6-fold exceeding that of the wild type. Optimal conditions for the production of CMCase by the mutant fungal strain using solid-state fermentation were examined. The optimized medium consisted of sugarcane bagasse supplemented with 1% (w/w) peptone, 2.5 mM MgSO4, and 0.05% (v/w) Tween 80. Optimal moisture content and initial pH was 40% (v/w) and 5.0 to 6.5, respectively. The medium was fermented at 40°C for 4 days. The resulting CMCase yield was 4.0-fold more than that of the wild type strain grown on the basal wheat bran medium. Some characteristics of partially purified CMCase from the mutant and wild type of C. cellulolyticum were investigated. The partially purified mutant CMCase was more stable than the wild type CMCase. Thus, the higher thermostability of mutant CMCase makes it a potential candidate for commercial and industrial process. Key word: Chaetomium cellulolyticum, carboxymethyl cellulase, mutation, optimization, solid state fermentation, characterization.

Distribution of sterigmatocystin in filamentous fungi

During the last 50 y, the carcinogenic mycotoxin sterigmatocystin (ST) has been reported in several phylogenetically and phenotypically different genera: Aschersonia, Aspergillus, Bipolaris, Botryotrichum, Chaetomium, Emericella, Eurotium, Farrowia, Fusarium, Humicola, Moelleriella, Monocillium and Podospora. We have reexamined all available strains of the original producers, in addition to ex type and further strains of each species reported to produce ST and the biosynthetically derived aflatoxins. We also screened strains of all available species in Penicillium and Aspergillus for ST and aflatoxin. Six new ST producing fungi were discovered: Aspergillus asperescens, Aspergillus aureolatus, Aspergillus eburneocremeus, Aspergillus protuberus, Aspergillus tardus, and Penicillium inflatum and one new aflatoxin producer: Aspergillus togoensis (= Stilbothamnium togoense). ST was confirmed in 23 Emericella, four Aspergillus, five Chaetomium, one Botryotrichum and one Humicola species grown on a selection of secondary metabolite inducing media, and using multiple detection methods: HPLC–UV/Vis DAD, – HRMS and – MS/MS. The immediate precursor for aflatoxin, O-methylsterigmatocystin was found in Chaetomium cellulolyticum, Chaetomium longicolleum, Chaetomium malaysiense and Chaetomium virescens, but aflatoxin was not detected from any Chaetomium species. In all 55 species, representing more than 11 clades throughout the Pezizomycotina, can be reliably claimed to be ST producers and 13 of these can also produce aflatoxins. It is not known yet whether the ST/aflatoxin pathway has been developed independently 11 times, or is the result of partial horizontal gene transfer.

Degradation of digestion residues by lignolytic fungi

In different European countries new legislative regulations and laws demand the reduction of the amount of wastes. In nature, the reduction steps of organic compounds in waste material are managed by symbiotic organisms, where a combination of aerobic and anaerobic degradation sequences leads to a near mineralization of organic material. Modeled on this principle, the process presented here combines a two-stage digestion with a following aerobic mineralization step. To gain a maximum amount of methane which is a regenerative energy carrier, the process reducing organic waste—in this case kitchen refuse— was begun by a run through a digestion cascade. The residues from the anaerobic step, containing mainly lignocellulosic substances that are recalcitrant to anaerobic degradation, were concentrated and then treated aerobically by white-rot and soft-rot fungi. In this article, it is demonstrated that many fungi species can use digestion residues as a substrate. The soft-rot fungus Chaetomium cellulolyticum could aerobically degrade the digestion residues, measured as volatile solid reduction of 39%. Within the process, lignin was reduced by almost 45%. Exposed again to the digestion, these residues of the aerobic treatment were degraded anaerobically with a rate of 42%. Therefore, a three-stage process combining anaerobic, aerobic and anaerobic degradation leads to organic matter reduction of more than 96% of the original amount. It can be concluded at least that organic waste material can almost completely be mineralized by biotechnological treatment.

Characterization of neutral xylanases from Chaetomium cellulolyticum and their biobleaching effect on eucalyptus pulp

Chaetomium cellulolyticum produced three xylanases with molecular weights of 25, 47, and 57 kDa and pIs of 8.9, 8.4, and 5.0, respectively. According to their biochemical characteristics and specificity, the 25- and 47-kDa xylanases were related to the family of G and the 57-kDa xylanase to the family of F. These xylanases had a neutral pH optimum within the range of 6–7 and the 25-kDa xylanase maintained high activity at alkaline pH up to 10. An important characteristic of the 25-kDa xylanase was its high stability at pH 9. Bleaching effects of xylanases from C. cellulolyticum on eucalyptus pulp were examined. The 25-kDa xylanase had higher than other xylanases isolated and commercial preparation Ecopulp TX 200 biobleaching activity at pH 9. All of the xylanases exhibited endo-action patterns, slight differences in the ratio of low-molecular weight sugars were detected. Changes in molecular weight distributions of xylan were observed to be the same for xylanases from C. cellulolyticum confirming the endo-mode of action of these enzymes.

Investigation of the use of agricultural byproducts for fungal protein production

Cellulose and nutrient salts as well as potato pulp and potato protein liquor (PPL), were used as substrates for the cultivation of Chaetomium cellulolyticum in batch and repeated-batch operations. Using cellulose as the substrate a linear relationship existed between the rates of cell mass formation and acid production. The repeated-batch process was controlled by NaOH consumption using a simple computer model. When the production of cell mass and acid stopped because of a lack of substrate cellulose was fed into the reactor. This occurred within 10 min at which point no NaOH-feed was needed to maintain a constant pH. Repeated-batch operations yielded higher cell concentrations and productivities than batch operations. The relationship between the NaOH and H 2SO 4 consumed, and the fungal mass concentration was complex in cultivation media containing potato pulp and PPL, because various substrates were consumed by the fungus simultaneously and successively. Therefore, for repeated-batch cultivation a constant time interval was used. Repeated-batch cultivation of the fungus on potato pulp and PPL did not yield higher cell concentrations and productivities than did batch cultivation. With the optimal pulp-to-PPL ratio a maximum specific growth rate of 0.61 h 1 was obtained. These investigations indicate, that potato pulp and PPL are well suited to fungal protein production by Chaetomium cellulolyticum for fodder supplement.

Screening microbial strain for improving the nutritional value of wheat and corn straws as animal feed

From 18 strains of cellulolytic microorganisms including bacteria and filamentous fungi, one strain of soft rot fungus identified as Chaetomium cellulolyticum was screened with respect to stronger decomposition ability of cellulose and hemicellulose and its ability for protein synthesis. As it grew on raw corn straw in solid layer fermentation (SLF) for 5 days, the amino acid content in the fermentation product attained 19.29% (w/w) from 6.43% while the total cell wall was reduced by 54%. A toxicity test with mice showed that the fermentation product is not poisonous. The two filamentous fungi, Trichoderma pseudokoningii S-38 and Penicillium decumbens JU-A10 produced large amounts of extracellular cellulase and hemicellulase in the SLF process, but their growth was limited and they sporulated profusely with regard to their value as animal feed products.

Inhibition of cellulose saccharification and glycolignin-attacking enzymes of five lignocellulose-degrading fungi by ferulic acid

At 5 g/l, ferulic acid, a plant cell-wall phenolic, severely repressed growth of the lignocellulose-degrading fungi Trichoderma harzianum, Chaetomium cellulolyticum, Phanaerochaete chrysosporium, Trametes versicolor and Pleurotus sajor-caju. At 0.5 g/l, howerver, it slightly stimulated growth of the latter two organisms. Two classes of extracellular enzymes involved in cellulose and glycolignin breakdown were assayed: cellulases; and phenol oxidases as laccases. All of the strains depolymerized cellulose but two (T. versicolor and P. sajor-caju) also secreted laccases. Laccase-secreting fungal species had normal levels of cellulose saccharification except in the presence of 5 g ferulic acid/l, whereas saccharification by the other strains was suppressed at all concentrations of the phenolic tested.

Growth of Chaetomium cellulolyticum in solid-state fermentation of sugar cane bagasse treated with water and alkali at several liquid/solid ratios

Sugar cane bagasse was water- or alkali-treated at three liquid/solid (L/S) ratios and its digestibility was measured as microbial protein production of Chaetomium cellulolyticum grown on solid-state fermentation columns. The treatments significantly enhanced fungus growth compared to non-treated bagasse, which was used as a control, although the composition of bagasse did not change greatly. Alkali-treated bagasse reached an average protein content of about 7.6% and the lower the L/S ratio, the higher the protein content. L/S ratio did not have an effect in water-treated bagasse. Protein content of water-treated bagasse was also high, approximately 80% of that one of alkali-treated bagasse. Both treatments look promising to enhance sugar cane bagasse potential as an animal feed.

Analyses of fungal fermentation of lignocellulosic substrates using continuous culture rumen simulation.

In vitro rumen digestibility of five lignocellulosic materials (rice bran, ryegrass-hay, barley straw, birch and spruce sawdusts) were assessed before and after solid substrate fermentations with Coriolus versicolor, Pleurotus sajo-caju, Phanerochaete chrysosporium, Chaetomium cellulolyticum, and Trichoderma harzianum. In studies with spruce sawdust, marked reductions in gas and volatile acid production were observed after 4 days of simulated rumen fermentation. With the fermented sawdusts, increases in digestibility and daily carbon dioxide production were observed as the fermentation proceeded. Chitin and D(+)-glucosamine, major components of fun gal cell walls enhanced digestibility, acetate output and total gas production except at concentrations > 30% w/w chitin or > 1 % w/v glucosamine which gave adverse results. The presence of high levels of mycelial biomass observed visually in fungal fermented rice bran, hay and barley straw did not appear to enhance digestibility

In sacco degradability of straw treated with cellulolytic enzymes containing fermented substrates

Four fungi varieties (Wild variety, Chaetomium cellulolyticum, Trichoderma harzianum and Penicillium colony 10) were cultivated in a solid‐state fermentation on a wheat straw‐wheat bran‐sugar beet pulp mixture (20 : 40: 40%). The fermented substrates contained xylanase (22.1 to 78.6 Units g‐1 DM) and cellulase (0.47 to 14.0 Units g‐1 DM). Fermented substrate was homogeneously mixed with ground wheat straw (1: 2; 1: 5 and 1 : 10), moistened to 30 or 50% DM, airtightly stored for 24 h at 50°C and deep frozen. All samples were given in nylon bags and incubated for 48 h in the rumen of 4 sheep. In sacco DMD decreased with higher straw proportions in the mixture (1: 2; 1 : 5 and 1: 10: 52.0; 46.8 and 44.2% resp.), the DM‐content did not significantly influence the in sacco DMD. The Wild variety and Chaetomium cellulolyticum did not significantly influence the in sacco DMD, Trichoderma harzianum and Penicillium colony 10 decreased DMD in some cases. In general added fungi did not improve the rumen degradability of fibre.

Fermentation of cellulosic materials to mycoprotein foods

A new bioprocess is described in which a cellulolytic, food-grade fungus Neurospora sitophila converts cellulosic materials to protein-rich products for food and fodder. The optimal conditions for the conversion are identified: 35–37 °C temperature, pH 5.5, 2.35 ms -1 agitator tip speed. Scale-up of the production process to 1,300 L is reported. The mycoprotein production data on several types of cellulosic materials (sugarcane bagasse, corn stover, wood cellulose) are presented. The performance of N. sitophila is found to compare favourably with that of Chaetomium cellulolyticum, another cellulolytic organism previously reported on by us.

Liquid‐Phase mass transfer coefficients in bioreactors

Liquid-phase mass transfer coefficient in bioreactors have been examined. A theoretical model based on the surface renewal concept has been developed. The predicted liquid-phase mass transfer coefficients are compared with the experimental data for a mycelial fermentation broth (Chaetomium cellulolyticum) and model media (carboxymethyl cellulose) in a bench-scale bubble column reactor. The liquid-phase mass transfer coefficient is evaluated by dividing the volumetric mass transfer coefficient obtained experimentally by the specific surface area estimated using the available correlations. The available literature data in bubble column and stirred tank bioreactors is also used to test the validity of the proposed model. A reasonable agreement between the model and the experimental data is found.

Hydrodynamics in bubble column bioreactors with fermentation broths having a yield stress

The hydrodynamics in a bubble column bioreactor with fermentation broths having a yield stress are studied. Specifically, the liquid velocity at the reactor axis, the axial dispersion coefficient, and the gas hold-up are examined. The liquid velocity at the reactor axis and the gas hold-up are measured in a 40-1 bench-scale bubble column fermentor using carboxypolymethylene (Carbopol) aqueous solutions as simulated broths. Theoretical correlations for the liquid velocity at the reactor axis, the axial dispersion coefficient, and the gas hold-up are derived on the basis of an energy balance and the mixing length theory. The correlations are compared with the present data and a reasonable agreement is found. The theoretical predictions are also in satisfactory agreement with the re-examined data for actual fermentation broths which are Chaetomium cellulolyticum and Neurospora sitophila cultured in a 1000-1 pilot-plant scale airlift fermentor.

Microbial biomass protein from the fungus Chaetomium cellulolyticum. II. Effect of method of drying and response to amino acid supplementation

A Chaetomium cellulolyticum microbial biomass protein (MBP) culture produced on glucose substrate in a batch process was divided in half before drying. One half was dried in a forced-draft oven at 60°C (oven-dried, OD), the other half was frozen at −25°C and freeze-dried (FD) to a dry matter content of 90%. The crude protein contents of the OD and FD samples were 48.9 and 48.0%, respectively. Purified diets calculated to contain 10% crude protein were fed to weanling male Sprague-Dawley rats for two weeks. A control diet contained casein as the only protein source, another included isolated soyabean protein (ISP) as the sole source of protein. In two other diets, one half of the crude protein was provided by ISP and the other half by MBP-OD or MBP-FD. The diet containing the OD sample yielded poorer growth, feed consumption and feed utilization efficiency than the diets containing ISP plus the FD sample. All three of these diets showed significant responses to supplementation with 0.4% dl-methionine and a slight but non-significant improvement with the further addition of 0.15% l-lysine. The double-supplemented MBP diets, however, showed a weight gain that was significantly greater than that of the similarly supplemented ISP diet and similar to that of the casein control diet. The rats receiving the MBP basal diets showed the lowest feed consumption, whereas with amino acid supplementation they showed the highest consumption. The relatively poor feed gain ratio of the rats fed the MBP-OD diet alone or fully supplemented indicated a lower feed and dietary protein utilization efficiency than the control or the fully-supplemented MBP-FD group. Dry matter and crude protein digestibility values, however, were similar for the unsupplemented MBP diets. Therefore, observed differences in body weight gain and feed gain ratios must have been due to differences in nutrient utilization resulting from differences in the drying methods, freeze-drying being the preferred method. However, the tremendous improvement in response to amino acid supplementation of this fungal MBP product overcomes the difference between the two methods. It also provides good grounds for optimism for the future use of this non-conventional protein source in animal production.

Microbial biomass protein from the fungus Chaetomium cellulolyticum. III. Nutritive value for chicks and piglets

The nutritive value of Chaetomium microbial biomass protein (MBP) samples grown on glucose or molasses was evaluated in combination with soya-bean protein in diets of chicks and piglets. Performance records and digestibility values observed with chicks fed on these blended proteins compared well with similar blends of brewers' or Torula yeast with soya-bean protein. Body weight gains in relation to protein intakes were expressed in terms of net protein ratio and protein efficiency ratio values for these dietary protein sources for chicks and the results were similar. In a practical diet for weanling pigs, the fungal MBP grown on molasses replaced 50% of the dietary protein supplied by soya-bean meal with excellent results.

Microbial biomass protein from the fungus Chaetomium cellulolyticum. I. Composition and nutritive evaluation

Microbial biomass protein (MBP) products of the cellulolytic fungus Chaetomium cellulolyticum were produced in batch culture with glucose substrate (MBP-1W) or molasses substrate (MBP-2W) as the main carbon source. Their chemical composition and nutritive values were compared with other MBP feedstuffs, Torula yeast, brewers' yeast and dried mushrooms. C. cellulolyticum MBP products contained about 45% crude protein on a dry matter basis and their amino acid profiles after acid hydrolysis compared well with that of dried skim milk, but the total amino acids analyzed accounted for only 75.6 and 62.5% of the crude protein of the MBP-1W and MBP-2W, respectively, compared to 81.8% for dried skim milk. In a 4-week growth trial, weanling male rats were fed on purified diets with the test material providing the only source of protein at a level of 10%. Product MBP-1W gave a 4-week weight less than that on brewers' yeast but greater than that on the Torula yeast diet. The MBP-2W and dried mushrooms gave the lowest body weights and feed consumption apparently because of their poor acceptability to the test animals. Brewers' yeast protein showed the highest PER value of the MBP diets but was significantly lower than the casein control diet. Its value was significantly greater than that of the MBP-1W with similar protein intake. Torula yeast showed a significantly higher PER value than MBP-1W, although protein intake was lower. Product MBP-2W and dried mushrooms, under very low dietary intakes gave similar low PER values. The NPR values, being greatly influenced by intake levels, proved to be a much less useful measure of protein quality. Dry matter digestibility ranged from 86% for the mushroom diet to 96% for the control casein diet. The MBP-1W and MBP-2W diets were inferior to the Torula yeast and brewers' yeast diets. Digestibility of crude protein was also highest for the casein diet, averaging close to 93% for the second and fourth week measurements, followed by Torula yeast with an average of 82%. The MBP-1W average digestibility of 78.7% was similar to that of brewers' yeast (77.3%) and superior to that of the MBP-2W and the dried mushroom diets. However, the latter diets had low intakes which result in underestimation of digestibility. Overall, the fungal MBP products tested showed reasonable potential as a new source of protein. The fungal protein grown on glucose was superior in nutritive value to that grown on molasses mainly because of its greater acceptability.

Aerobic biodegradation of organic matter of swine waste

Degradation of organic matter of swine waste is dependent on the metabolic activity of the indigenous microorganisms. Although the composition of the centrifuged wastes varied, a reduction of about 80% of the chemical oxygen demand (COD) was obtained in each case when incubated at 37°C and 250 rpm without pH control. However, the time required by the indigenous mesophilic microflora for such stabilization of the waste was a function of the initial COD concentration. The agitation speed influenced the rate of organic matter degradation, while pH control between 7 and 8 and lowering the temperature to 22°C had no effect. The inoculation of selected strains isolated from treated waste or activated sludge to swine waste did not accelerate the degradation of organic matter. An adapted strain of Chaetomium cellulolyticum when inoculated in stabilized waste, reduced by a factor of two the remaining COD after 4 days of incubation. Samples from different environments were inoculated in stabilized waste and after incubation of these cultures dominant bacterial strains were isolated. When inoculated in stabilized waste these strains reduced only slightly the remaining COD. Optimization of degradation of organic matter of swine waste supernatant is possible but appears to be limited by the presence of substances of low degradability.

Oxygen transfer to mycelial fermentation broths in an airlift fermentor

Oxygen transfer rates and gas holdups were measured in mycelial fermentation broths of Chaetomium cellulolyticum and Neurospora sitophila, each cultured in a 1300-L pilot-plant-scale airlift fermentor. These cultures exhibited highly non-Newtonian flow behavior coupled with a substantial decrease in oxygen transfer rates. The volumetric mass transfer coefficients in these cultures were found to be 65-70% lower than those in water. The data were compared with the available correlations obtained for simulated fermentation broths. In general, the data for C. cellulolyticum are in satisfactory agreement with the correlations for the model media but the data for N. sitophila are higher than that predicted by the correlations. Model media based correlations are found to be applicable to the fermentation processes if the culture medium does not possess a high yield stress.

Bioconversion of hemicelluloses into fungal protein

The utilization of cellulose from one ton of lignocellulose for ethanol production would yield 150–250 kg of hemicelluloses. The total soluble solids in the hemicellulose fraction (HF) obtained with the Universite de Sherbrooke (UdeS) process contained about 56% carbohydrates. These carbohydrates were present in the form of oligomers of various sugars, predominantly xylose. All the test fungi,Chaetomium cellulolyticum, C. cellulolyticum (asporogenous mutant) andPleurotus sajor-caju, were capable of utilizing all the carbohydrates present in HF.C. cellulolyticum gave the highest amount of protein (7 g/l) from 19 g carbohydrates/l. The yield of protein was higher than expected, indicating that carbon compounds other than reducing sugars present in HF might have been consumed for fungal growth. The inhibitory effect of toxic compounds on protein production increased with an increase in concentration of soluble solids in HF. The inhibitory effect was overcome by increasing the pH of the medium to 6.0 or 7.0. Fungal protein production from hemicelluloses will give extra revenue in our integrated approach for ethanol production from lignocelluloses.