Analysis of inducers of xylanase and cellulase activities production by Ganoderma applanatum LPB MR-56

Effect of Different Inducer Sources on Cellulase Enzyme Production by White-Rot Basidiomycetes Pleurotus ostreatus and Phanerochaete chrysosporium under Submerged Fermentation

Cellulase enzymes attract a lot of research due to their industrial application. Diverse cellulase-producing organisms and substances that induce cellulase are highly sought after. This study aimed to evaluate the effect of different inducer sources on cellulase production by white rot fungi P. ostreatus CGMCC 3.7292 and P. chrysosporium CGMCC 3.7212 under submerged fermentation employing a completely randomized experimental design. The different inducer sources tested were nitrogen (yeast, potassium nitrate, sodium nitrate, ammonium sulphate, aqueous ammonia and urea), carbon (malt extract, glucose, fructose, carboxymethylcellulose, starch and xylose) and agro-biomass (stevia straw, wheat straw, oat straw, alfalfa straw, corn cobs and corn stover). These inducer sources strongly impacted enzyme activities by P. ostreatus CGMCC 3.7292 and P. chrysosporium CGMCC 3.7212. The suitable nitrogen and carbon inducer sources for cellulase activity by P. ostreatus and P. chrysosporium were yeast (1.354 U/mL and 1.154 U/mL) and carboxymethylcellulose (0.976 U/mL and 0.776 U/mL) while the suitable agro-biomass were wheat straw (6.880 U/mL) and corn stover (6.525 U/mL), respectively. The least inducer sources in terms of nitrogen, carbon and agro-biomass for cellulase activity by P. ostreatus and P. chrysosporium were urea (0.213 U/mL and 0.081 U/mL), glucose (0.042 U/mL and 0.035), xylose (0.042 U/mL and 0.035 U/mL) and stevia straw (1.555 U/mL and 0.960 U/mL). In submerged fermentation, the cellulase enzyme activity of P. ostreatus in response to various inducer sources was relatively higher than P. chrysosporium.

Development of Sustainable Biorefinery Processes Applying Deep Eutectic Solvents to Agrofood Wastes

The growing demand for renewable energies and the application of sustainable and economically viable biorefinery processes have increased the study and application of lignocellulosic biomass. However, due to lignocellulosic biomass recalcitrance hindering its efficient utilization, the pretreatment in the biorefinery is an essential stage for success in the process. Therefore, Deep Eutectic Solvent (DES) has emerged as a promising green pretreatment. During this study, the effect of choline chloride [ChCl]:glycerol and [ChCl]:urea on sugarcane bagasse and brewery bagasse is evaluated. Results have demonstrated that using [ChCl]:glycerol in SCB reduced about 80% and 15% for acid-soluble lignin and Klason lignin, respectively, and improved efficiency on saccharification yields, achieving conversions of 60, 80, and 100% for glucan, xylan, and arabinan, correspondingly. In the case of BSG saccharification yields, about 65% and 98% are attained for glucan and xylan, respectively, when [ChCl]:glycerol was employed. These results confirm the effectiveness and facility of DES pretreatment as a suitable method that can improve the biorefinery processes.

Effect of barley straw and Egyptian clover hay on the rumen fermentation and structure and fibrolytic activities of rumen bacteria in dromedary camel

Background and Aim: Understanding the regulations of rumen microbiota and their fibrolytic capabilities under different forages are essential to improve rumen fermentation and animal feed efficiency. This study aimed to evaluate the changes in the rumen fermentation and the structure and fibrolytic activities of rumen bacteria in camels fed barley straw and Egyptian clover hay. Materials and Methods: Three fistulated camels were fed a diet containing barley straw for 30 days; then transitioned to a diet containing Egyptian clover hay for 30 days. In addition, bacterial media enriched with xylan and different cellulose sources, namely, filter paper, wheat straw, and alfalfa hay, were used to evaluate the ability of camel rumen bacteria to produce xylanase and cellulase enzymes. Results: The camel group fed Egyptian clover hay showed higher crude protein intake, rumen ammonia, total volatile fatty acids, and acetic acid. Moreover, the camel group fed barley straw showed higher neutral detergent fiber intake, rumen pH, and propionic and butyric acids. Principal component analysis showed that bacterial communities were separated based on the forage type. Forage type affected the composition of rumen bacteria and most of the bacterial community was assigned to phylum Bacteroidetes and Firmicutes. Egyptian clover hay diet increased the proportions of genus Prevotella and Ruminococcus; while fed barley straw diet increased the Butyrivibrio, RC9_gut_group, and Fibrobacteres. The bacterial culture of the Egyptian clover hay fed group produced the greatest xylanase and the bacterial culture of the barley straw fed group produced the maximum cellulase. Conclusion: Egyptian clover hay is recommended to feed camels in intensive production. Moreover, the bacterial community in the camel rumen is a promising source of lignocellulolytic enzymes.

Fungal interactions induce changes in hyphal morphology and enzyme production

In nature, species interacts/competes with one other within their surrounding for food and space and the type of interactions are unique to each species. The interacting partners secrete different metabolites, which may have high importance in human welfare. Fungal-fungal interactions are complex mechanisms that need better understanding. Here, 14 fungal isolates were facilitated in 105 possible combinations to interact on potato dextrose agar. Morphologically, no changes were observed when the same fungal isolates were allowed to interact within them. However, 10 interactions between different fungal isolates showed mutual replacement with each fungus; capturing territory from the other. Contrastingly, 35 interactions resulted into complete replacement as one of the fungi was inhibited by rapid growth of the other fungus. In 46 interactions, formation of barrage was observed leading to deadlock type of interaction wherein both fungi have restricted growth. To study in details about the barrage formation, two fungal interactions were taken (i) T. coccinea vs. L. lactinea and (ii) T. coccinea vs. T. versicolor. Microscopic changes in the hyphal growth during interaction were observed. There was significant increase in the enzymatic activities including cellulase, xylanase and chitinase during in-vitro fungal-fungal interaction, suggesting the importance of such interactions for commercial enzyme production.

Lignocelluloytic activities and composition of bacterial community in the camel rumen

The camel is well-adapted to utilize the poor-quality forages in the harsh desert conditions as the camel rumen sustains fibrolytic microorganisms, mainly bacteria that are capable of breaking down the lignocellulosic biomass efficiently. Exploring the composition of the bacterial community in the rumen of the camel and quantifying their cellulolytic and xylanolytic activities could lead to understanding and improving fiber fermentation and discovering novel sources of cellulases and xylanases. In this study, Illumina MiSeq sequencing of the V4 region on 16S rRNA was applied to identify the bacterial and archaeal communities in the rumen of three camels fed wheat straw and broom corn. Furthermore, rumen samples were inoculated into bacterial media enriched with xylan and different cellulose sources, including filter paper (FP), wheat straw (WS), and alfalfa hay (AH) to assess the ability of rumen bacteria to produce endo-cellulase and endo-xylanase at different fermentation intervals. The results revealed that the phylum Bacteroidetes dominated the bacterial community and Candidatus Methanomethylophilus dominated the archaeal community. Also, most of the bacterial community has fibrolytic potential and the dominant bacterial genera were Prevotella, RC9_gut_group, Butyrivibrio, Ruminococcus, Fibrobacteres, and Treponema. The highest xylanase production (884.8 mU/mL) was observed at 7 days. The highest cellulase production (1049.5 mU/mL) was observed when rumen samples were incubated with Alfalfa hay for 7 days.

The Carbon Source Controls the Secretion and Yield of Polysaccharide-Hydrolyzing Enzymes of Basidiomycetes

In the present study, the polysaccharide-hydrolyzing secretomes of Irpex lacteus (Fr.) Fr. (1828) BCC104, Pycnoporus coccineus (Fr.) Bondartsev and Singer (1941) BCC310, and Schizophyllum commune Fr. (1815) BCC632 were analyzed in submerged fermentation conditions to elucidate the effect of chemically and structurally different carbon sources on the expression of cellulases and xylanase. Among polymeric substrates, crystalline cellulose appeared to be the best carbon source providing the highest endoglucanase, total cellulase, and xylanase activities. Mandarin pomace as a growth substrate for S. commune allowed to achieve comparatively high volumetric activities of all target enzymes while wheat straw induced a significant secretion of cellulase and xylanase activities of I. lacteus and P. coccineus. An additive effect on the secretion of cellulases and xylanases by the tested fungi was observed when crystalline cellulose was combined with mandarin pomace. In I. lacteus the cellulase and xylanase production is inducible in the presence of cellulose-rich substrates but is suppressed in the presence of an excess of easily metabolizable carbon source. These enzymes are expressed in a coordinated manner under all conditions studied. It was shown that the substitution of glucose in the inoculum medium with Avicel provides accelerated enzyme production by I. lacteus and higher cellulase and xylanase activities of the fungus. These results add new knowledge to the physiology of basidiomycetes to improve cellulase production.

α-Amylase and cellulase production by novel halotolerant Bacillus sp.PM06 isolated from sugarcane pressmud

A novel Bacillus sp.PM06 isolated from sugarcane waste pressmud was tested for extracellular α-amylase and cellulase enzyme production. The effect of different substrates, nitrogen sources, pH, and temperature on growth and extracellular enzyme production was examined. Bacillus sp.PM06 was able to grow with starch and carboxymethyl cellulose (CMC) as a sole source of carbon and ammonium chloride was found to be the best nitrogen source. Maximum enzyme production was obtained at 48 H for both α-amylase and cellulase. The optimal condition for measuring enzyme activity was found to be pH 5.5 at 50 °C for α-amylase and pH 6.4 at 60 °C for cellulase respectively. It was found that Bacillus sp.PM06 exhibited halotolerance up to 2 M Sodium chloride (NaCl) and Potassium chloride (KCl). The isolate could produce α-amylase in the presence of 2 M NaCl and 1 M KCl. However, the strain produced cellulase even in the presence of 2 M NaCl and KCl. Concomitant production of both enzymes was observed when the medium was supplemented with starch and CMC. A maximum of 31 ± 1.15 U/mL of amylase and 15 ± 1.5 U/mL of cellulase was produced in 48 H. The enzyme was partially purified by Ammonium sulphate (NH₄ )₂ SO₄ precipitation with 2.2 and 2.3-fold purification.

Screening and characterization of amylase and cellulase activities in psychrotolerant yeasts

Background

Amylases and cellulases have great potential for application in industries such as food, detergent, laundry, textile, baking and biofuels. A common requirement in these fields is to reduce the temperatures of the processes, leading to a continuous search for microorganisms that secrete cold-active amylases and cellulases. Psychrotolerant yeasts are good candidates because they inhabit cold-environments. In this work, we analyzed the ability of yeasts isolated from the Antarctic region to grow on starch or carboxymethylcellulose, and their potential extracellular amylases and cellulases.

Result

All tested yeasts were able to grow with soluble starch or carboxymethylcellulose as the sole carbon source; however, not all of them produced ethanol by fermentation of these carbon sources. For the majority of the yeast species, the extracellular amylase or cellulase activity was higher when cultured in medium supplemented with glucose rather than with soluble starch or carboxymethylcellulose. Additionally, higher amylase activities were observed when tested at pH 5.4 and 6.2, and at 30–37 °C, except for Rhodotorula glacialis that showed elevated activity at 10–22 °C. In general, cellulase activity was high until pH 6.2 and between 22–37 °C, while the sample from Mrakia blollopis showed high activity at 4–22 °C. Peptide mass fingerprinting analysis of a potential amylase from Tetracladium sp. of about 70 kDa, showed several peptides with positive matches with glucoamylases from other fungi.

Conclusions

Almost all yeast species showed extracellular amylase or cellulase activity, and an inducing effect by the respective substrate was observed in a minor number of yeasts. These enzymatic activities were higher at 30 °C in most yeast, with highest amylase and cellulase activity in Tetracladium sp. and M. gelida, respectively. However, Rh. glacialis and M. blollopis displayed high amylase or cellulase activity, respectively, under 22 °C. In this sense, these yeasts are interesting candidates for industrial processes that require lower temperatures.

Electronic supplementary material

The online version of this article (doi:10.1186/s12866-016-0640-8) contains supplementary material, which is available to authorized users.

Bioreactors for lignocellulose conversion into fermentable sugars for production of high added value products

Lignocellulosic biomasses derived from dedicated crops and agro-industrial residual materials are promising renewable resources for the production of fuels and other added value bioproducts. Due to the tolerance to a wide range of environments, the dedicated crops can be cultivated on marginal lands, avoiding conflict with food production and having beneficial effects on the environment. Besides, the agro-industrial residual materials represent an abundant, available, and cheap source of bioproducts that completely cut out the economical and environmental issues related to the cultivation of energy crops. Different processing steps like pretreatment, hydrolysis and microbial fermentation are needed to convert biomass into added value bioproducts. The reactor configuration, the operative conditions, and the operation mode of the conversion processes are crucial parameters for a high yield and productivity of the biomass bioconversion process. This review summarizes the last progresses in the bioreactor field, with main attention on the new configurations and the agitation systems, for conversion of dedicated energy crops (Arundo donax) and residual materials (corn stover, wheat straw, mesquite wood, agave bagasse, fruit and citrus peel wastes, sunflower seed hull, switchgrass, poplar sawdust, cogon grass, sugarcane bagasse, sunflower seed hull, and poplar wood) into sugars and ethanol. The main novelty of this review is its focus on reactor components and properties.