Days Of Solid State Fermentation Research Articles

Green biocatalyst for decolorization of azo dyes from industrial wastewater: Coriolopsis trogii 2SMKN laccase immobilized on recycled brewer's spent grain.

This study presents an innovative approach for the reuse and recycling of waste material, brewer's spent grain (BSG) for creating a novel green biocatalyst. The same BSG was utilized in several consecutive steps: initially, it served as a substrate for the cultivation and production of laccase by a novel isolated fungal strain, Coriolopsis trogii 2SMKN, then, it was reused as a carrier for laccase immobilization, aiding in the process of azo dye decolorization and finally, reused as recycled BSG for the second successful laccase immobilization for six guaiacol oxidation, contributing to a zero-waste strategy. The novel fungal strain produced laccase with a maximum activity of 171.4 U/g after 6 days of solid-state fermentation using BSG as a substrate. The obtained laccase exhibited excellent performance in the decolorization of azo dyes, both as a free and immobilized, at high temperatures, without addition of harmful mediators, achieving maximum decolorization efficiencies of 99.0%, 71.2%, and 61.0% for Orange G (OG), Congo Red, and Eriochrome Black T (EBT), respectively. The immobilized laccase on BSG was successfully reused across five cycles of azo dye decolorization process. Notably, new green biocatalyst outperformed commercial laccase from Aspergillus spp. in the decolorization of OG and EBT. GC-MS and LC-MS revealed azo-dye degradation products and decomposition pathway. This analysis was complemented by antimicrobial and phytotoxicity tests, which confirmed the non-toxic nature of the degradation products, indicating the potential for safe environmental disposal.

Solid-state fermentation with Zygomycetes fungi as a tool for biofortification of apple pomace with γ-linolenic acid, carotenoid pigments and phenolic antioxidants

In the last few years, there has been a growing interest in the more efficient utilization of agricultural and food by-products. Apples are among the most processed fruits in the world that generate huge quantities of processing waste biomasses. Therefore, the objective of this study was to improve the nutritional value of apple pomaces with γ-linolenic acid (GLA) and carotenoid pigments by solid-state fermentation (SSF) using two Zygomycetes fungi (Actinomucor elegans and Umbelopsis isabellina). The impact of fermentation periods on the polyphenol content and antioxidant capacity of the bioprocessed apple pomace was also investigated. The accumulated lipids were composed primarily of neutral fractions (mostly triacylglycerols). SSF with U. isabellina yielded a 12.72% higher GLA content than with A. elegans (3.85 g GLA/kg DW of pomace). Contrary to the lipogenic capacity, A. elegans showed higher carotenoids and phenolic antioxidants productivity than U. isabellina. The maximum concentrations for β-carotene (433.11 μg/g DW of pomace-SSF with A. elegans and 237.68 μg/g DW of pomace-SSF with U. isabellina), lutein (374.48 μg/g DW- A. elegans and 179.04 μg/g DW- U. isabellina) and zeaxanthin (247.35 μg/g DW- A. elegans and 120.41 μg/g DW- U. isabellina) were registered on the 12th day of SSFs. In the case of SSF with A. elegans, the amount of total phenolics increased significantly (27%) by day 4 from the initial value (2670.38 μg of gallic acid equivalents/g DW) before slowly decreasing for the remaining period of the fungal growth. The experimental findings showed that a prolonged fermentation (between 8 and 12 days) should be applied to obtain value-added apple pomaces (rich in GLA and carotenoids) with potential pharmaceutical and functional food applications. Moreover, the SSF processes of simultaneous bioaccumulation of valuable fatty acids, carotenoids and phenolic antioxidants proposed in the present study may open up new challenges for biotechnological production of industrially important biomolecules using abundant and unexploited apple pomaces.

Effects of Four Strains of Actinomycetes on the Content of Terpenoids in Baijiu.

Terpenoids not only are an important health factor in baijiu but also contribute to the elegance and finesse of baijiu, and actinomycetes act as an important source of terpenoids in baijiu. Four strains of actinomycetes-Streptomyces violascens (SPQ1), S. sampsonii (SPS1), S. thermophilus (SPG1), and S. griseus (SPH1)-obtained from the Daqu, pit mud, fermented grains and air, respectively, in the production of baijiu were used in solid-state and liquid fermentation with five brewing raw materials as the substrates. The terpenoids in the metabolites were analyzed and compared using gas chromatography-mass spectrometry (GC-MS). We found that the four strains of actinomycetes produced 31 terpenoids from the hydrolysates of five fermentation substrates during liquid fermentation, and the total terpenoid content was 989.94 μg/kg in the fermentation products. After 28 days of solid-state fermentation, the four actinomycete strains produced 64 terpenoids using the five fermentation substrates, and the total terpenoid content was 23,651.52 μg/kg in the fermentation products. The different fermentation substrates and fermentation methods have a great influence on the terpenoids produced by actinomycetes.

Antioxidant and antiproliferative potentials of phenolic-rich extracts from biotransformed grape pomace in colorectal Cancer

BackgroundColorectal carcinoma is one of the most commonly diagnosed malignancies worldwide. Consumption of dietary supplements and nutraceuticals such as phenolic compounds may help combat colorectal carcinoma. The effect of two phenolic-rich extracts prepared from biotransformed grape pomace on the antioxidant properties and antiproliferative activity against two colorectal cancer cell lines (Caco-2 and SW620) were investigated.MethodsA 15-day solid-state fermentation with the white-rot fungi Phanerochaete chrysosporium and Trametes gibbosa was used to biotransform grape pomace. Solid-liquid extraction was then performed to extract bioactive compounds. The extract was analyzed for the determination of phenolic compounds by ultra-high performance liquid chromatography and in vitro assays of biological activities (antioxidant activity, antiproliferative activity, cell cycle analysis).ResultsThe 4 days of solid-state fermentation proved to be the optimal period to obtain the maximum yield of phenolic compounds. The tested extracts showed significant antioxidant and antiproliferative activities. Grape pomace treated with P. chrysosporium and T. gibbosa reduced cancer cell growth by more than 60% at concentrations (solid/liquid ratio) of 1.75 mg/mL and of 2.5 mg/mL, respectively. The cell cycle perturbations induced by the grape pomace extracts resulted in a significant increase in the number of cells in the S (9.8%) and G2/M (6.8%) phases of SW620 exposed to T. gibbosa after 48 hours, while P. chrysosporium increased the percentage of cells in the G1 phase by 7.7%. The effect of grape pomace extracts on Caco-2 was less pronounced.ConclusionsThe obtained results suggest the presence of bioactive compounds in biotransformed grape pomace as a residue from winemaking, which could be used to prevent colon cancer.

Effect of Solid-State Fermentation on the Essential Oil Yield of Curcuma longa Residues.

The solid waste of Curcuma longa rhizomes generated after its cold juice process making is mostly unused and discarded even though they can contain essential oil. Conventional techniques such as hydrodistillation can be used to extract essential oil, but this generally results in low essential oil yield and inefficient extraction time. Solid-state fermentation as a pretreatment of distillation could improve the yield of essential oil. In this study, we evaluated the effect of solid state fermentation on the yield of extraction of Curcuma longa solid wastes essential oil. The solid-state fermentation was carried out naturally without any addition of inoculum and the extraction was performed by hydrodistillation. Under experimental conditions at room temperature (25^{circ }hbox {C}) with a moisture content of 44% and anaerobically in the dark, the treatment of 7 days of solid state fermentation followed by 2 h of hydrodistillation provided the highest yield of 1.21% as compared to non-fermented of 0.35% and of 0.96% relative to the raw plant material representing an increase of 71% and 21% respectively. A set of experiments was then carried out by a Doehlert matrix to optimize the yield of extraction. Two independent variables, namely the distillation time and the fermentation time, were studied. Under optimal experimental conditions of 10 days and 4 h, a yield of 1.96% was obtained validating the statistical model. The solid state fermentation applied before the hydrodistillation step has been successful and proves its potential to improve the efficiency of essential oil extraction.Graphical

Enzymatic Pretreatment Improved the In Vitro Ruminal Degradability of Oil Palm Fronds

This study aims to increase the in vitro ruminal degradability of oil palm fronds (OPFs) through enzymatic pretreatment. The isolated fungi were selected based on their lignocellulosic degrading enzyme activities. Eleven fungi were successfully isolated, and their enzyme activities were evaluated. Three fungi, F1, F2 and F4 were selected, and they were identified as Trichoderma harzianum MK027305, Trichoderma harzianum MK027306 and Fusarium solani MK027309, respectively. The highest total gas and methane production was produced when OPFs were pretreated with an enzyme extract from 15 and 30 days of solid-state fermentation of T. harzianum MK027305 and T. harzianum MK027306, respectively. Meanwhile, OPFs pretreated with an enzyme extract from F. solani MK027309 after 45 days of solid-state fermentation produced the highest amount of volatile fatty acids. The pretreatment using the enzymes extracted from 45 days of solid-state fermentation of F. solani MK027309 increases the apparent rumen degradable carbohydrate (ARDC) by 35.29% compared to unpretreated OPF. This study showed that pretreatment of the OPFs using selected fungi’s enzymes increases the volatile fatty acid production and in vitro ruminal degradability of OPF, hence improving livestock production via increased utilization of agricultural by-products with minimal impact on the production cost.

Degradation of pretreated agroforestry residues by selected micromycetes

Nowadays, there are huge amounts of lignocellulosic materials left in agroforestry practice, which can be transformed into useful products. Biomass exploitation could be aiming not only at replacing conventional energy sources but also at preserving biodiversity and natural ecosystems. Five micromycetes were studied with goal to determine their potential to produce active cellulases as well as the ability to decompose pretreated wheat straw and oak sawdust after seven days of solid-state fermentation. Wheat straw was better lignocellulosic substrate than oak sawdust for the production of cellulases in all five micromycetes. Thus, Penicillium solitum BEOFB 1190m has shown to be the best producer of highly active forms of xylanases (7532.36 ? 89.37 U/L). The most active endo- and exocellulases (2299.70 ? 72.17 U/L and 195.66 ? 4.64 U/L, respectively) were produced by Trichoderma harzianum BEOFB 1230m, while the maximal value of ?-glucosidase activity (215.69 ? 3.13 U/L) was detected after Fusarium graminearum BEOFB 820m cultivation. T. harzianum also showed high efficiency in wheat straw cellulose and hemicellulose depolymerization (23.90% and 33.00%, respectively), which resulted in the highest dry matter loss (36.25%). The results of the study showed great potential of tested micromycetes to synthesize cellulolytic enzymes and consequently transform abundant, low-cost plant residues such as wheat straw into useful products including biofuel.

Lignocellulosic residue valorization in a sequential process of solid‐state fermentation and solid substrate anaerobic digestion

AbstractBACKGROUNDLignocellulosic residue valorization is a relevant topic because the study of residue and waste recycling is essential for circular economy development. This area is focused on treatment development for value‐added compound production. This work presents a sequential process of solid‐state fermentation (SSF) by white‐rot fungi (WRF) followed by solid substrate anaerobic digestion (SSAD) with the objective of producing bioenergy and other ancillary product. The agricultural residue from common bean pod (Phaseolus vulgaris) has never been studied for the purpose of a biorefinery concept. In addition, the intermediate stage for enzyme recovery was evaluated, comparing two extractants on their enzyme stability and effectiveness effect and the subsequence SSAD process effect.RESULTSTrametes versicolor produced the highest enzymatic activity of laccase, reaching 1588 U L−1 at 12 days of SSF. Under this condition, both extractants showed excellent enzymatic stability at 17 °C, but only the enzymes recovered with phosphate buffer were capable of the micropollutant degradation. SSF caused an increase in biodegradability of the lignocellulosic residue, providing an increase in biogas yield between 0% and 75.5%; however, high volatile solids consumption during fungal growth decreased the amount of biogas per volatile solid mass before treatment.CONCLUSIONCommon bean pods were successfully valorized through the sequential process by SSF of the WRF T. versicolor and SSAD, producing enzymes as a value‐added product and biogas from the remaining solids. The enzymes produced were stable and effective for micropollutant degradation when they were recovered with phosphate buffer. © 2021 Society of Chemical Industry (SCI).

Scale-Up of Duddingtonia flagrans Chlamydospores Production from Laboratory to Pilot-Scale Using a Solid-State Fermentation System.

The fungus Duddingtonia flagrans is a biological control tool to reduce infective larvae of gastrointestinal nematode in pastures. To create a commercially available bioproduct based on a nematophagous fungus, an efficient mass production process should be developed that is able to guarantee a good predatory capacity and satisfactory production rates. In this work, solid-state fermentation (SSF) parameters were investigated to produce D. flagrans at pilot-scale. The results showed that the relative humidity was a critical factor to increase productivity and to reduce fermentation time. The best production conditions using a tray bioreactor were a relative humidity in the room at 90% for 2days, and inoculation by sprinkling. The fermentation process was composed of 7days under submerged fermentation to produce the inoculum and 7 more days of SSF in a tray bioreactor. The productivity reached was 4.96 × 106 chlamydospores g-1 of dry substrate day-1, which is the highest productivity reported to date. The predatory capacity of the chlamydospores produced using this process was 91%. Also, a statistical control process analysis was applied, finding that the process presents stability in the biological activity, yield, and final moisture content of the substrate between batches. Finally, the operational expenses (OPEX) based on the use of the heating and humidification system were estimated, given a final cost of 0.20 USD g-1 of the fermented substrate.

From stale bread and brewers spent grain to a new food source using edible filamentous fungi

ABSTRACT By-products from the food sector with a high load of organic matter present both a waste-handling problem related to expenses and to the environment, yet also an opportunity. This study aims to increase the value of stale bread and brewers spent grain (BSG) by re-introducing these residues to the food production chain by converting them to new protein-enriched products using the edible filamentous fungi Neurospora intermedia and Rhizopusoryzae. After 6 days of solid state fermentation (at 35°C, with a95% relative humidity and moisture content of 40% in the substrate) on stale bread, a nutrient-rich fungal-fermented product was produced. The total protein content, as analyzed by total amino acids, increased from 16.5% in stale sourdough bread to 21.1% (on dry weight basis) in the final product with an improved relative ratio of essential amino acids. An increase in dietary fiber, minerals (Cu, Fe, Zn) and vitamin E, as well as an addition of vitamin D2 (0.89 µg/g dry weight sample) was obtained compared with untreated stale bread. Furthermore, addition of BSG to the sourdough bread with the aim to improve textural changes after fermentation showed promising outcomes. Cultivation of N. intermedia or R. oryzae on stale sourdough bread mixed with 6.5% or 11.8% BSG, respectively, resulted in fungal-fermented products with similar textural properties to a commercial soybean burger. Bioconversion of stale bread and BSG by fungal solid state fermentation to produce a nutrient-enriched food product was confirmed to be a successful way to minimize food waste and protein shortage.

Simultaneous enrichment of grape pomace with γ-linolenic acid and carotenoids by solid-state fermentation with Zygomycetes fungi and antioxidant potential of the bioprocessed substrates

Two filamentous fungi (Actinomucor elegans and Umbelopsis isabellina), were tested for their ability to enrich white grape pomace simultaneously with both γ-linolenic acid (GLA) and carotenoids through solid-state fermentation (SSF) processes. U. isabellina presented higher ability to produce GLA-rich lipids (composed mainly of neutral fractions) than A. elegans (the 6-th day of SSF: 378.85 mg/100 g of pomace –U. isabellina and 193.36 mg/100 g of pomace– A. elegans). The amounts of β-carotene and lutein for both SSFs gradually increased until the end of the fermentation processes. The effect of fermentation time on the phenolic content and antioxidant activity of grape pomace was also studied. The SSF with A. elegans increased significantly total phenolic and flavonoid contents and DPPH scavenging activity of grape popmace.These bioprocessed grape pomaces with significant amounts of carotenoids and GLA-rich lipids (>94% nutritionally-valuable polyunsaturated fatty acids at the sn-2 position) could be very attractive for food industry.

Effect of proteolytic bacteria on texture and colour quality of khanom-jeen, traditional Thai fermented rice noodles.

Khanom-jeen are traditional Thai fermented rice noodles with a characteristic flavour and texture. Based on their ability to hydrolyse rice proteins, five strains of proteolytic bacteria were isolated from fermented rice flour used to produce noodles in Thailand. Enterobacter ludwigii strain SK01 showed the highest degree of rice protein hydrolysis among the five strains and was selected as a starter culture for khanom-jeen production. The viable count of micro-organisms, acidity, pH, and protein and starch contents were compared throughout the fermented rice production with and without the SK01 strain. The pH of fermented rice increased on the first day of solid-state fermentation and subsequently decreased to 3·7-3·8 under both conditions. The protein content of rice significantly decreased from 80 to 18·2±0·5mgg-1 and 26±0·6mgg-1 during fermentation with and without the SK01 strain, respectively. The tensile strength, breaking length, brightness, and whiteness, which are important factors for the texture and appearance of khanom-jeen, were improved using the SK01 strain to ferment rice. The results of this laboratory-scale study indicated that the use of the proteolytic SK01 strain in fermented rice production can improve the quality of khanom-jeen noodles. SIGNIFICANCE AND IMPACT OF THE STUDY: The use of Enterobacter ludwigii strain SK01 as a proteolytic bacterial starter culture improved the quality of khanom-jeen noodles. Compared with khanom-jeen noodles produced without E. ludwigii strain SK01, those produced using this strain showed increased tensile strength, breaking length, brightness and whiteness. These findings will be useful for the development of specific and controllable methods for producing khanom-jeen noodles with desirable texture and colour.

Optimization of solid-state fermentation conditions of Bacillus licheniformis and its effects on Clostridium perfringens-induced necrotic enteritis in broilers

ABSTRACT In the present study, we examined the growth parameters of Bacillus licheniformis in solid-state fermentation (SSF) and evaluated the effects of Bacillus licheniformis-fermented products on Clostridium perfringens-challenged broilers. During four and six days of SSF, the highest viable biomass was observed at 5% glucose, 10% soybean meal, 3% yeast, and 50% initial moisture content. The Bacillus licheniformis SSF products were heat- and acid-resistant. Furthermore, the fermented products were able to inhibit the growth of Clostridium perfringens and Staphylococcus aureus [...]

Microbial oil production from solid-state fermentation by a newly isolated oleaginous fungus, Mucor circinelloides Q531 from mulberry branches.

In this study, a newly isolated oleaginous fungus, Mucor circinelloides (M. circinelloides) Q531, was able to convert mulberry branches into lipids. The highest yield and the maximum lipid content produced by the fungal cells were 42.43 ± 4.01 mg per gram dry substrate (gds) and 28.8 ± 2.85%, respectively. The main components of lignocellulosic biomass were gradually reduced during solid-state fermentation (SSF). Cellulose, hemicellulose and lignin were decreased from 45.11, 31.39 and 17.36% to 41.48, 28.71, and 15.1%, respectively. Gas chromatography analysis showed that the major compositions of the fermented products were palmitic acid (C16:0, 18.42%), palmitoleic acid (C16:1, 5.56%), stearic acid (C18:0, 5.87%), oleic acid (C18:1, 33.89%), linoleic acid (C18:2, 14.45%) and γ-linolenic acid (C18:3 n6, 22.53%) after 2 days of SSF. The fatty acid methyl esters contained unsaturated fatty acids with a ratio of 75.95%. The composition and content obtained in this study are more advantageous than those of many other biomass lipids. Meanwhile, the oleaginous fungus had a high cellulase activity of 1.39 ± 0.09 FPU gds−1. The results indicate that the enzyme activity of the isolated fungus was capable of converting the cellulose and hemicelluloses to available sugar monomers which are beneficial for the production of lipids.

Assessment of protease activity in hydrolysed extracts from SSF of hair waste by and indigenous consortium of microorganisms

Hair wastes from the tannery industry were assessed for its suitability as substrates for protease production by solid-state fermentation (SSF) using a pilot-batch mode operation and anaerobically digested sludge as co-substrate. Maximum protease activity (52,230±1601Ug−1DM) was observed at the 14th day of SSF. Single step purification resulted in 2 fold purification with 74% of recovery by ultrafiltration with 10kDa cut-off. The recovered enzyme was stable at a temperature of 30°C and pH 11; optimal conditions that were determined by a central composite full factorial experimental design. The enzyme activity was inhibited by phenylmethylsulfonyl fluoride, which indicates that it belongs to serine protease group. The remaining solid material after protease extraction could be easily stabilized to obtain a final good quality compost-like material as the final dynamic respiration index was lower than 1gO2kg−1OMh−1. The lyophilized recovered enzymes were a good alternative in the process of cowhides dehairing with respect to the current chemical treatment, avoiding the production of solid wastes and highly polluted wastewaters. In conclusion, the entire process can be considered a low-cost sustainable technology for the dehairing process, closing the organic matter cycle in the form of value added product and a compost-like material from a waste.

Valorization of soy waste through SSF for the production of compost enriched with Bacillus thuringiensis with biopesticide properties

There is a growing generation of biodegradable wastes from different human activities from industrial to agricultural including home and recreational activities. On the other hand, agricultural and horticultural activities require significant amounts of organic amendments and pesticides. In this framework, the present study evaluates the viability of soy fiber residue valorization as organic soil amendment with biopesticide properties through aerobic solid-state fermentation (SSF) in the presence of Bacillus thuringiensis (Bt). The experiments were performed first under sterile and non-sterile conditions at lab scale using 115 g of sample and controlled temperature (30 °C). Bt growth was successful in sterile conditions, obtaining 6.2 × 1011 CFU g−1 DM and 8.6 × 1010 spores g−1 DM after 6 days. Bt survived on solid culture under non-sterile conditions (3.8 × 109 CFU g−1 DM and 1.3 × 108 spores g−1 DM). Further, the valorization process was scaled-up to 10 L reactors (2300 g) under non-sterile conditions obtaining a final stabilized material with viable Bt cells and spores (9.5 × 107 CFU g−1 DM and 1.1 × 108 spores g−1 DM in average) after 9 days of SSF. These results confirm the possibility of managing biodegradable wastes by their transformation to a waste derived soil amendment with enhanced biopesticide effect, in comparison to traditional compost using a valuable and low-cost technique (SSF).

Enhanced degradation of lignin in corn stalk by combined method of Aspergillus oryzae solid state fermentation and H2O2 treatment

To shorten the time of corn stalk pretreatment and increase the degradation of lignin, solid state fermentation (SSF) with Aspegillus oryzae CGMCC5992 in the presence of H2O2 was carried out to degrade lignin in stalk. In this study, the conditions for lignin hydrolysis catalyzed by enzymes produced in SSF for 10 days were optimized by mono-factor-at-a-time design and response surface method (RSM). The removal rate of lignin increased from 30% (before hydrolysis) to 80.3% (after hydrolysis) under the temperature of 55 °C, pH 6.0, water/stalk ratio of 40, and the concentration of H2O2 at 4% (w/w). In comparison, the removal rate of lignin after 50 days of SSF only reached 57.8%. Proteomic analysis provided support for the increased lignin hydrolysis. Fermentation with A. oryzae CGMCC5992 in the presence of H2O2 increased the amount of peroxidase and intracellular catalase and decreased the amount of extracellular catalase. Therefore, the method introduced in this study can significantly shorten the time of SSF and increase the removal rate of lignin.

Cold active holocellulase cocktail from Aspergillus niger SH3: process optimization for production and biomass hydrolysis

The conversion of cellulosic biomass into monomeric sugars is the most costly and energy intensive process in bioethanol production. Cold active cellulases produced by psychrophilic microorganisms can counter this limitation by hydrolyzing the biomass at low temperature. Enrichment of soil samples collected from the Himalayan region of India, at 5 °C and molecular identification revealed the prominence of phylum ascomycota. The hydrolytic potential of all isolates in terms of cellulases and xylanases were tested at different temperatures and isolate A. niger SH3 which exhibited significantly higher enzyme production at low temperature. Thereafter, experimental mixture design was employed to study the influence of different carbon sources (e.g. wheat bran, wheat straw and paddy straw). A. niger SH3 gave highest titer of endoglucanase (655.94 IU/g), β-glucosidase (540.57 IU/g), FPase (31.48 IU/g) and xylanase (1951.63 IU/g) under the optimized conditions after 7 days of solid state fermentation. Hydrolysis of pretreated paddy straw using the crude hydrolytic enzymes (15 FPU/gds) of A. niger SH3 at 40 °C resulted in maximum sugar yield (375.84 ± 0.23 mg/gds). This study proves the potential of A. niger SH3 secretome for efficient biomass hydrolysis at low temperature and its suitability for developing an energy efficient biofuel production process.

Chemical composition and protein enrichment of orange peels and sugar beet pulp after fermentation by two Trichoderma species.

The present experiment aimed at increasing orange peel and sugar beet pulp protein content through solid-state fermentation by Trichoderma reesei and Trichoderma viride. In vitro digestibility and changes in the chemical composition of the fermented products were determined after seven days of fungal cultivation using gas production tests. The cultivation of T. reesei and T. viride on orange peels decreased neutral detergent soluble content (P<0.01) and increased cellulose, hemicellulose and lignin contents (P<0.01). Changes in fiber fractions were found to be more pronounced with T. viride. The cultivation of T. reesei and T. viride on sugar beet pulp increased neutral detergent soluble content (P<0.01) and decreased cellulose and hemicellulose contents (P<0.01). These changes were more pronounced with T. reesei. The cultivation of T. reesei or T. viride on orange peels or sugar beet pulp increased crude protein content (P<0.01) compared with the unfermented materials; however, the increase was more pronounced for orange peels fermented with T. viride when corrected for weight loss (P<0.05). After 24 and 48 h of incubation, significant decreases in cumulative gas production (P<0.01) were observed in fermented sugar beet pulp and orange peels compared with the unfermented materials. Fungal treatment of orange peels and sugar beet pulp reduced the digestibility of in vitro organic matter, metabolizable energy and average fermentation and gas production rates (P<0.01). The data showed that seven days of solid-state fermentation of orange peels and sugar beet pulp by T. reesei or T. viride can increase their crude protein content.

Mycota of distillery yeast sludge as source of single cell protein

This study focused on the isolation, identification, and utilization of the mycota present in distillery yeast sludge as source of single cell protein. Seven fungal isolates were described and identified. These include three species of yeasts (Saccharomyces cerevisiae Meyen ex E.C. Hansen, Candida parapsilosis (Ashford) Langeron and Talice, and Candida guilliermondii (Castellani) Langeron et Guerra) and four species of molds (Aspergillus flavus Link, Aspergillus niger van Teigh, Aspergillus japonicus Saito var japonicus, and Rhizopus sp.). The ability of the fungal isolates to produce single cell protein was evaluated by determining the crude protein content (CPC) of the distillery yeast sludge after 14 days of solid state fermentation. Results revealed that inoculation of the seven taxa produced significantly higher percentage CPC of the distillery yeast sludge. Apparently, S. cerevisiae-treated distillery yeast sludge had the highest percentage CPC of 33.7% and the highest percentage increase in CPC of 34.3%, while Rhizopus sp.-treated distillery yeast sludge had the lowest of 21.8%. Thus, the present study indicates the great potential of the seven taxa as source of single cell protein using the distillery sludge as substrate.