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Chaetomidium arxii was recovered from dead, overwintering adults of Eurygaster integriceps in northern Iran. The species was identified based on morphological characteristics as well as sequence data from LSU and ITS-rDNA regions. This is first report on the occurrence of C. arxii on sunn pest and a new record of C. arxii for Iran. The fungus is fully illustrated and described.

Four novel compounds, chaephilone C (1), chaetoviridides A–C (2–4), were obtained from the culture of a deep sea derived fungus Chaetomium sp. NA-S01-R1, together with four known compounds—chaetoviridin A (5), chaetoviridine E (6), chaetomugilin D (7) and cochliodone A (8). Their structures, including absolute configurations, were assigned based on NMR, MS and time-dependent density functional theory (TD-DFT) ECD calculations. A plausible biogenetic pathway for compounds 1–3 was proposed. Compounds 2 and 3 exhibited antibacterial activities against Vibrio rotiferianus and Vibrio vulnificus. Compounds 1, 3 and 4 displayed similar anti-methicillin resistant Staphylococcus aureus (anti-MRSA) activities in comparison to chloramphenicol. Compound 2 showed the most potent cytotoxic activities towards the Hep G2 cell and compounds 1 and 3 demonstrated relatively stronger cytotoxic activities than the other compounds against the HeLa cell.

[Display omitted] • Twelve non-reported indole alkaloids possibly derived from indole-3-glycerophosphate were isolated from the solid-state fermented rice medium of the fungus Chaetomium nigricolor YT-2. • Chaetonigrisin A (1) represents an unprecedented carbon skeleton featuring a polycyclic 1H-pyrano[3,2:3,4-] furo[2, 3- b] indole. Chaetonigrisin B (2) displays a unique carbon skeleton with a 1,3‑dioxolane bridged-ring. Chaetonigrisin C (3) is a spirocyclic indole alkaloid. Chaetonigrisins D – H (4 – 8) are a group of asymmetric dimers, formed with two 3-indol-3yl-1,2-propanediol (4 – 6) or with a 3-indol-3yl-1,2-propanediol and a 3-indol-2yl-1,2-propanediol (7 – 8) by a pyran ring. Chaetonigrisins I – L (9 – 12) each contains a 3-indol-3yl-1,2-propanediol or 3-indol-2yl-1,2-propanediol substructure. • Chaetonigrisin G (7) showed significant neuroprotective activity via upregulation of upregulation of SOD1 mRNA and Bcl2 mRNA. Thirteen new alkaloids (1 – 13) as well as ten known compounds were isolated from the solid-state fermented rice medium of the fungus Chaetomium nigricolor YT-2. Their structures were elucidated on the basis of spectroscopic data, quantum calculations, and single crystal X-ray crystallographic analysis. Chaetonigrisin A (1) represents an unprecedented carbon skeleton featuring a polycyclic 1H-pyrano[3,2:3,4-]​furo[2,​3-​b]​indole. Chaetonigrisin B (2) displays a unique carbon skeleton with a 1,3‑dioxolane bridged-ring. Chaetonigrisin C (3) is a spirocyclic indole alkaloid. Chaetonigrisins D – H (4 – 8) are a group of asymmetric dimers, formed with two 3-indol-3yl-1,2-propanediol (4 – 6) or with a 3-indol-3yl-1,2-propanediol and a 3-indol-2yl-1,2-propanediol (7 – 8) by a pyran ring. Chaetonigrisins I – L (9 – 12) each contains a 3-indol-3yl-1,2-propanediol or 3-indol-2yl-1,2-propanediol substructure. Chaetonigrisin M (13) is a new quinoline alkaloid. The neuroprotective activity assay showed that at the concentration of 40 μ M, compounds (4 – 7 , 11 , and 12) improved the cell viability of PC12 cells were 49.26 %, 74.69 %, 74.76 %, 86.63 %, 66.89 %, and 69.92 %, respectively induced by 6-OHDA, compound 7 showed significant neuroprotective activity via upregulation of SOD1 mRNA and Bcl-2 mRNA. [ABSTRACT FROM AUTHOR]

• Chaetomium species is widespread worldwide and rarely cause infection in human. • This is the first reported case of endocarditis caused by Chaetomium species. • Mortality is high for invasive Chaetomium infections. • Molecular tools are used to confirm the diagnosis in Chaetomium infections. • Appropriate treatment for Chaetomium infections is unknown. Chaetomium globosum is a dematiaceous, filamentous fungus belonging to the large genus saprobic ascomycetes and is rarely involved in human infection. We present the case of a 25-year-old man undergoing tricuspid valve replacement due to recurrent prosthetic ring endocarditis. Initially, it was considered culture-negative endocarditis; however, the diagnosis of Chaetomium globosum could only be provided by DNA isolation of the mold isolate grown in culture and the valve tissue samples taken from the patient. This report describes the first documented tricuspid endocarditis caused by Chaetomium species and discusses the importance of molecular tools to enhance the diagnostic process in culture-negative endocarditis, especially for fastidious and nonculturable microorganisms. [ABSTRACT FROM AUTHOR]

Plants will interact with beneficial endophytic fungi to increase resistance under environmental stress. Among these stresses, salt stress poses one of the major threats to plant growth worldwide. We have studied the response mechanism of Chaetomium globosum D5, a salt-tolerant fungus isolated from the roots of Paeonia lactiflora under salt stress, and its mechanism of action in helping P. lactiflora alleviate salt stress. In our study, high levels of salt inhibit growth, whereas low levels promote the growth of C. globosum D5, which resists salt stress by forming dense hyphae and producing more pigments, soluble proteins, and antioxidants. Under salt stress, growth and photosynthesis of P. lactiflora are inhibited, and they are subjected to osmotic stress, oxidative stress, and ionic stress. C. globosum D5 could help P. lactiflora promote growth and photosynthesis by increasing the uptake of nitrogen and phosphorus and increasing the accumulation of the carbon and photosynthetic pigments, help P. lactiflora alleviate osmotic stress by increasing the accumulation of proline, help P. lactiflora alleviate ion stress by reducing Na+ and increasing K+/Na+, Ca2+/Na+ and Mg2+/Na + ratios in P. lactiflora roots and leaves. In summary, joint action between P. lactiflora and C. globosum D5 is responsible for mitigating damage caused by P. lactiflora under salt stress. We first investigate the interaction between the fungus and P. lactiflora under salt stress, providing a theoretical basis for further investigations into the mechanisms of P. lactiflora 's response to salt stress and its promotion in coastal areas. [ABSTRACT FROM AUTHOR]

Microbial-driven straw-derived soil organic carbon (SOC) sequestration plays pivotal role in promoting soil productivity and achieving C neutrality, while nitrogen (N) and phosphorus (P) input levels are the impetus of this process. However, our understanding of the microbial mechanism underpinning the straw-derived SOC fractions accumulation within aggregates under contrasting N and P application rates is rudimentary. Here, a 90-day incubation experiment was conducted to observe the dynamics of straw-derived SOC fractions accumulation within aggregates by adding C 3 straw (natural 13C-labeled substrate) to a Mollisol (in which C 3 plants had never been grown). Treatments included straw combinations of half N and regular P (N 1/2 +P + SR), regular N and half P (N + P 1/2 +SR) and regular N and P (N + P + SR). Regular N input accelerated the succession of the microbial community from bacteria-dominated to fungi-dominated and increased the contents of straw-derived particulate OC (POC) at 10 days and mineral-associated OC (MOC) at 30 days within aggregates. Differential abundance analysis and slopes of linear regression models showed that the fungal community, especially the core enriched taxon of Chaetomiaceae, was strongly positively correlated with straw-derived MOC after N input. Random forest models strengthened the view that N input rate and Chaetomiaceae richness may directly mediate straw-derived POC and MOC accumulation process, respectively, during incubation. To verify our conjecture, another 60-day incubation experiment was carried out to elucidate the effects of Chaetomium globosum inoculation and N application on SOC turnover after straw addition. Chaetomium globosum inoculation with regular N input promoted straw decomposition and SOC sequestration than other treatments, but no difference was observed in soil respiratory quotient compared with control. The slopes of linear regression model show the more significant and positive correlations between SOC content and Chaetomiaceae richness in the present study than data from previous references, impling the important role of Chaetomiaceae in SOC sequestration in Mollisols. Our work provides new ecophysiological angles for understanding the effect of Chaetomiaceae richness on the accrual of SOC in response to varying N levels in agroecosystems on the Northeast China Plain. [Display omitted] • We reveal the pathway of straw to SOC fractions by determining δ13 C. • N input levels regulate straw-derived SOC accumulation process, rather than P. • Succession of guides from bacteria to fungi optimized straw-derived SOC accumulation. • Chaetomiaceae's function in SOC accumulation was validated via culture inoculation. • Chaetomium globosum inoculation promoted SOC sequestration under regular N input. [ABSTRACT FROM AUTHOR]

Tricrilactones A-H (1-8), a new family of oligomeric 10-membered macrolides featuring collectively five unique ring skeletons, were isolated from a hitherto unexplored fungus, Trichocladium crispatum. Compounds 1 and 7 contain two unconventional bridged (aza)tricyclic core skeletons, 2, 3, 5, and 6 share an undescribed tetracyclic 9/5/6/6 ring system, 4 bears an uncommon 9/5/6/10/3-fused pentacyclic architecture, and 8 is a dimer bridged by an unexpected C-C linkage. Their structures, including absolute configurations, were elucidated by spectroscopic analysis, quantum chemical calculations, and X-ray diffraction analysis. Importantly, the absolute configuration of the highly flexible side chain of 1 was resolved by the asymmetric synthesis of its four stereoisomers. The intermediate-trapping and isotope labeling experiments facilitated the proposal of the biosynthetic pathway for these macrolides. In addition, their antiosteoporosis effects were evaluated in vivo (zebrafish)., (© 2023 Wiley-VCH GmbH.)

The potato cyst nematode (Globodera rostochiensis) is one of the most economically important pests of potato (Solanum tuberosum L.), causing significant economic losses worldwide. The identification of biocontrol agents for the sustainable management of G. rostochiensis is crucial. In this study, a potential biocontrol agent, Chaetomium globosum KPC3, was identified based on sequence analysis of the DNA internal transcribed spacer (ITS) region, the translation elongation factor 1-alpha (TEF1-α) gene, and the second largest subunit of the RNA polymerase II (RPB2) gene. The pathogenicity test of C. globosum KPC3 against cysts and second-stage juveniles (J2s) revealed that fungus mycelium fully parasitized the cyst after 72 h of incubation. The fungus was also capable of parasitizing the eggs inside the cysts. The culture filtrate of C. globosum KPC3 caused 98.75% mortality in J2s of G. rostochiensis after 72 h of incubation. The pot experiments showed that the combined application of C. globosum KPC3 as a tuber treatment at a rate of 1 lit kg -1 of tubers and a soil application at a rate of 500 ml kg -1 of farm yard manure (FYM) resulted in significantly lesser reproduction of G. rostochiensis compared to the rest of the treatments. Altogether, C. globosum KPC3 has the potential to be used as a biocontrol agent against G. rostochiensis and can be successfully implemented in integrated pest management programs., (© 2023. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Indoor fungi are a worldwide problem causing negative health effects for infected building's occupants and even deterioration of building structures. Different fungal species affect buildings and their inhabitants differently. Therefore, rapid and accurate identification of fungi to the species level is essential for health risk assessment and building remediation. This study focuses on molecular identification of two common indoor fungal genera: Stachybotrys and Chaetomium . This study proposes two new DNA barcode candidates for Stachybotrys and Chaetomium : the gene encoding mitogen activated protein kinase ( hogA ) and the intergenic region between histone 3 and histone 4 ( h3-h4 ) as well as it introduces a rapid - 3.5 h - protocol for direct Stachybotrys and Chaetomium species identification, which bypasses culture cultivation, DNA extraction and DNA sequencing. [ABSTRACT FROM AUTHOR]

Co-culturing the fungal endophyte Chaetomium sp. with the bacterium Bacillus subtilis on solid rice medium resulted in an up to 8.3-fold increase in the accumulation of constitutively present metabolites that included a 1:1 mixture of 3- and 4-hydroxybenzoic acid methyl esters ( 1 and 2 , respectively), and the polyketides acremonisol A ( 3 ), SB236050 ( 4 ), and SB238569 ( 5 ). In addition, seven compounds including isosulochrin ( 6 ), protocatechuic acid methyl ester ( 7 ), as well as five new natural products ( 8 – 12 ) were detected in the co-cultures, but not in axenic fungal cultures. Treatment of Chaetomium sp. with the epigenetic modifier suberoylanilide hydroxamic acid or 5-azacytidine resulted in an enhanced accumulation of 6 , which was likewise detected during co-culture. Compound 5 showed strong cytotoxicity against the mouse lymphoma L5178Y cell line with an IC 50 value of 1 μM, as well as weak antibacterial activity against B. subtilis with an MIC value of 53 μM. [ABSTRACT FROM AUTHOR]

Endo-polygalacturonases (PGs) of glycosyl hydrolase (GH) family 28 share a right handed parallel β-helical structure with a cleft formed by T1 and T3 loops. To reveal the effect of non-active-site residues on endo -PG catalysis, Thr113 of Achaetomium sp. endo -PG (PG8fn) located on the T3 loop was substituted. The experimental results indicated that the catalytic efficiency of PG8fn depends on the side-chain structure of residue at position 113, following the order of Glu (negatively charged) < Gly, Ala and Ile (nonpolar) < Ser, Gln and Thr (polar) < Arg and Lys (positively charged). Void pathway analysis demonstrated that substitution with Arg caused the increased occupancy rates of void pathways T2 and T3 and resulted in the improvement of catalytic efficiency by increasing the kinetics of substrate access ( k on ) or product release ( k off ). Further molecular dynamics (MD) simulations illustrated that the substitution enhanced the flexibility of T3 loop and influenced the interaction between enzyme and substrate. The functional role of Arg113 was also verified in another GH28 endo -PG by increasing the catalytic efficiency of ∼2.4-fold. This study proposes a novel strategy, i.e. selective modification of the non-active site residues, to improve the catalytic performance of GH28 PGs. [ABSTRACT FROM AUTHOR]

Pseudoprotodioscin ( 1 ) is a steroidal saponin from plants with diverse biological activities. In order to obtain new and useful derivatives for further study, Chaetomium olivaceum was used to transform pseudoprotodioscin. Five new ( 4 , 5 , 6 , 8 , and 9 ) and three known ( 2 , 3 and 7 ) steroidal saponins were obtained in this study. These reactions were hard to be achieved through chemical modification. The structures of these metabolites were elucidated on the basis of spectroscopic data. The possible biotransformation pathway of 1 by Chaetomium olivaceum was also proposed. Protective effects against H 2 O 2 -induced H9c2 cardiomyocyte injury of compounds 1 – 9 were evaluated. Compounds 1 , 4 and 6 showed some cell-protection activity. [ABSTRACT FROM AUTHOR]

Summary The 90S pre-ribosome is an early biogenesis intermediate formed during co-transcriptional ribosome formation, composed of ∼70 assembly factors and several small nucleolar RNAs (snoRNAs) that associate with nascent pre-rRNA. We report the cryo-EM structure of the Chaetomium thermophilum 90S pre-ribosome, revealing how a network of biogenesis factors including 19 β-propellers and large α-solenoid proteins engulfs the pre-rRNA. Within the 90S pre-ribosome, we identify the UTP-A, UTP-B, Mpp10-Imp3-Imp4, Bms1-Rcl1, and U3 snoRNP modules, which are organized around 5′-ETS and partially folded 18S rRNA. The U3 snoRNP is strategically positioned at the center of the 90S particle to perform its multiple tasks during pre-rRNA folding and processing. The architecture of the elusive 90S pre-ribosome gives unprecedented structural insight into the early steps of pre-rRNA maturation. Nascent rRNA that is co-transcriptionally folded and given a particular shape by encapsulation within a dedicated mold-like structure is reminiscent of how polypeptides use chaperone chambers for their protein folding. [ABSTRACT FROM AUTHOR]

Fungal endophytes are group of fungi that grow within the plant tissues without causing immediate signs of disease and are abundant and diverse producers of bioactive secondary metabolites. The Chaetomium genus of kingdom fungi is considered to be a rich source of unique bioactive metabolites. These metabolites belong to chemically diverse classes, i.e., chaetoglobosins, xanthones, anthraquinones, chromones, depsidones, terpenoids and steroids. Cheatomium through production of diverse metabolites can be considered as a potential source of antitumor, cytotoxic, antimalarial, antibiotic and enzyme inhibitory lead molecules for drug discovery. This review covers isolation of Cheatomium endophytes, extraction and isolation of metabolites and their biological activities. [ABSTRACT FROM AUTHOR]

Prp28 (pre-mRNA-splicing ATP-dependent RNA helicase 28) is a spliceosomal DEAD-box helicase which is involved in two steps of spliceosome assembly. It is required for the formation of commitment complex 2 in an ATP-independent manner as well as for the formation of the pre-catalytic spliceosome, which in contrast is ATP-dependent. During the latter step, Prp28 is crucial for the integration of the U4/U6·U5 tri-snRNP since it displaces the U1 snRNP and allows the U6 snRNP to base-pair with the 5′-splice site. Here, the crystal structure of Prp28 from the thermophilic fungus Chaetomium thermophilum is reported at 3.2 Å resolution and is compared with the available structures of homologues. [ABSTRACT FROM AUTHOR]

Chaetoviridins constitute a large family of structurally related secondary metabolites isolated from Chaetomium fungi. To elucidate the biosynthesis pathway and understand how the chemical diversity of chaetoviridins is generated, gene deletion and in vitro characterization of the four post-PKS modifications enzymes were undertaken. CazL and CazP were identified to have substrate promiscuity that facilitates the formation of nonchlorinated analogues. In addition, enzymatic oxidation and reduction combined with spontaneous dehydration and lactonization of the intermediates further expand the chemical diversity. [ABSTRACT FROM AUTHOR]

In Chaetomium thermophilum (DSM 1495) within the mitochondrial DNA (mtDNA) small ribosomal subunit (rns) gene a group IIA1 intron interrupts an open reading frame (ORF) encoded within a group I intron (mS1247). This arrangement offers the opportunity to examine if the nested group II intron could be utilized as a regulatory element for the expression of the homing endonuclease (HEase). Constructs were generated where the codon-optimized ORF was interrupted with either the native group IIA1 intron or a group IIB type intron. This study showed that the expression of the HEase (in vivo) in Escherichia coli can be regulated by manipulating the splicing efficiency of the HEase ORF-embedded group II introns. Exogenous magnesium chloride (MgCl2) stimulated the expression of a functional HEase but the addition of cobalt chloride (CoCl2) to growth media antagonized the expression of HEase activity. Ultimately the ability to attenuate HEase activity might be useful in precision genome engineering, minimizing off target activities, or where pathways have to be altered during a specific growth phase. [ABSTRACT FROM AUTHOR]

Moldy building materials, such as chip wood and gypsum, should be a good source for fungal strains with high production of lignocellulolytic enzymes. Screening of 21 common indoor fungal strains showed, contrary to the expected, that the Chaetomium and Stachybotrys strains had little or no cellulolytic and xylanolytic activities using AZCL-assays. On the other hand, both Cladosporium sphaerospermum and Penicillium chrysogenum showed the highest cellulase, β-glucosidase, mannase, β-galactanase and arabinanase activities and would be good candidates for over-producers of enzymes needed to supplement industrial enzyme blends or boost the bioconversion of lignocellulose-rich biomass. [ABSTRACT FROM AUTHOR]

The effects of inoculants on the composting ofSophora flavescensresidues were evaluated based on several physical, chemical and biological parameters, as well as the infrared spectra. Compared to the control compost without inoculants, the treatment compost with inoculants (Bacillus subtilisstrain G-13 andChaetomium thermophilumstrain GF-1) had a significantly longer thermophilic duration, higher cellulase activity and a higher degradation rate of cellulose, hemicellulose and lignin (P< 0.05). Thus, a higher maturity degree of compost with apparently lower C:N ratio (15.88 vs. 17.77) and NH4-N:NO3-N ratio (0.16 vs. 0.20) was obtained with the inoculation comparing with the control (P< 0.05). Besides, the inoculants could markedly accelerate the composting process and increase the maturity degree of compost as indicated by the germination index (GI) in which the treatment reached the highest GI of 133.2% at day 15 while the control achieved the highest GI of 125.7% at day 30 of the composting. Inoculation withB. subtilisandC. thermophilumis a useful method to enhance theS. flavescensresidues composting according to this study. [ABSTRACT FROM PUBLISHER]

RNA helicases are indispensable for all organisms in each domain of life and have implications in numerous cellular processes. The DEAH-box RNA helicase Prp43 is involved in pre-mRNA splicing as well as rRNA maturation. Here, the crystal structure of Chaetomium thermophilum Prp43 at 2.9 Å resolution is revealed. Furthermore, it is demonstrated that Prp43 from C. thermophilum is capable of functionally replacing its orthologue from Saccharomyces cerevisiae in spliceosomal disassembly assays. [ABSTRACT FROM AUTHOR]

Target of rapamycin (TOR), a conserved protein kinase and central controller of cell growth, functions in two structurally and functionally distinct complexes: TORC1 and TORC2. Dysregulation of mammalian TOR (mTOR) signaling is implicated in pathologies that include diabetes, cancer, and neurodegeneration.We resolved the architecture of human mTORC1 (mTOR with subunits Raptor and mLST8) bound to FK506 binding protein (FKBP)-rapamycin, by combining cryo-electron microscopy at 5.9 angstrom resolution with crystallographic studies of Chaetomium thermophilum Raptor at 4.3 angstromresolution.The structure explains how FKBP-rapamycin and architectural elements of mTORC1 limit access to the recessed active site. Consistent with a role in substrate recognition and delivery, the conserved amino-terminal domain of Raptor is juxtaposed to the kinase active site. [ABSTRACT FROM AUTHOR]

An isolate of Fusarium denominated as NHP-Fusa-2 from tea wilt and root-rot diseased sample collected in Vietnam was identified as Fusarium oxysporum based on molecular analysis of translation elongation factor-1α sequence. Interestingly, it is the first time F. oxysporum is reported as a causal pathogen of wilt and root-rot disease of tea in Vietnam. Chaetomium spp. were investigated to control F. oxysporum NHP-Fusa-2 in in vitro test. Three antagonists (Ch. cupreum CC3003, Ch. globosum CG05, and Ch. lucknowense CL01) inhibited mycelial growth by 31.69-34.03% and reduced conidial production of the pathogen by 67.25-75.92% in the bi-culture antagonistic test after 30 days with non-significant difference in their effect. All the crude extracts of these antagonists significantly inhibited mycelial growth and conidial production of NHP-Fusa-2. MeOH extract of CC3003 was more effective in conidial inhibition of the pathogen than the others, the effective dose (ED50) was 85.30 μg/ml of which, it was hexane (49.32 μg/ml) and EtOAc extract (62.17 μg/ml) in the case of CG05 and CL01, respectively. [ABSTRACT FROM AUTHOR]

Members of the family Chaetomiaceae are ubiquitous ascosporulating fungi commonly, which reside in soil enriched with manure or cellulosic materials. Their role as human pathogens is largely ignored. However, the ability of some species to grow at high temperature enables them to play an important role as opportunistic pathogens. The family contains several genera and species that have never been reported to cause human infection. Hereby, three new species are described; two belong to the genus Subramaniula and one represents a Chaetomium species. Subramaniula asteroides was isolated from various sources including eye and skin infections as well as from the natural environment, and S. obscura was isolated from a toe infection. Chaetomium anamorphosum was isolated from a kidney transplant patient suffering from fungal peritonitis. All species described were previously misidentified as Papulaspora spp. due to the formation of cellular clumps or bulbil-like structures, which are characteristic of Papulaspora. The isolates failed to form sexual fruit bodies and ascospores remained absent, which is an unusual feature for the generally ascosporulating genera Chaetomium and Subramaniula; minute conidia from phialides were sometimes observed. [ABSTRACT FROM AUTHOR]

Background: Cellulase is an important industrial enzyme used to degrade cellulosic biomass. The demand for cellulase enzyme is continuously increasing because of its applications in various industries. Hence, screening of cellulase producing microorganisms from different sources has gained significant importance. Material and Methods: In this study, fungi isolated from books and archives were screened for their cellulase producing abilities. Four different fungi were isolated from books and archives using potato dextrose agar. Screening of these isolates for cellulase production was carried out using carboxymethyl cellulose broth. The most efficient fungus was subjected to cellulase fermentation and enzymes produced were purified and partially characterized. Results: Four different fungi, Chaetomium sp., Aspergillus niger, Aspergillus nidulans and Penicillium sp., were isolated from books and archives. All the isolates were tested for their ability to produce cellulase enzyme. During the primary screening Chaetomium sp. showed good growth and higher cellulase activity (155.3±25.6 U/mL) in carboxymethyl cellulose medium than the other fungi. The cellulase fermentation study was conducted with Chaetomium sp. using carboxymethyl cellulose as a substrate. During the stationary phase (144 h) of the growth, the cellulase activity of Chaetomium sp. was significantly high. The maximum mycelial weight of this fungi was obtained at 168 h. Viscosity of the Chaetomium sp. inoculated fermentation medium continuously decreased until 144 h because of the degradation of carboxymethyl cellulose. During cellulase fermentation, pH increased from the initial neutral pH to 8.5. Purified cellulase showed a specific activity of 7.3 U/mg. It exhibited maximum activity at 20°C and was stable between pH 5 and 9. Conclusions: Books and archives could be a good source for the isolation of cellulase producing fungi. [ABSTRACT FROM AUTHOR]

Dextranase (DN) has generated interest due to its ability to hydrolyze dextran for the synthesis of isomalto-oligosaccharides (prebiotic). Here, DN from Chaetomium erraticum was purified by a combination of tangential ultrafiltration and ion-exchange chromatography, and then the enzyme was characterized. This enzyme has a molecular weight (Mw) of around 59 kDa, calculated by SDS-PAGE, and an Mw of 120 kDa estimated on zymogram, suggesting that the native form is a dimer. The purified DN exhibited a pH and temperature optimum of 5.2 and 60 °C, respectively. The DN-catalyzed hydrolysis of dextran followed Michaelis–Menten kinetics with K m and V max values estimated as 2.6 ± 0.1% (260 μM) and 2280 ± 9 μmol min −1 mg −1 protein, respectively. The activation energy was determined as 52.7 ± 0.4 kJ mol −1 , and the thermodynamic parameters (ΔG ‡ , ΔH ‡ and ΔS ‡ ) for the hydrolysis of dextran were also determined. Dextranase activity was enhanced by Ca 2+ , and especially Co 2+ at 1 mM, which improved its activity to 124.5 ± 3.0%, whereas Ni 2+ and Fe 3+ negatively affected activity. The main end-products of 100 kDa dextran hydrolysis by DN were isomaltose, isomaltotriose, and maltopentaose. Finally, it was found that the thermal inactivation mechanism for dextranase can be described by the first-order irreversible mechanism. [ABSTRACT FROM AUTHOR]

NAD + -dependent formate dehydrogenase (FDH) enzyme catalyses the NAD(P) + -dependent interconversion of formate anion to carbon dioxide coupled with the conversion of NAD(P) + to NAD(P)H. NADH is widely used as cofactor by enzymes utilized in the biocatalytic synthesis of chiral pharmaceutical intermediates and chemical compounds. For this reason, FDH is used in the enzymatic synthesis of optically active prochiral carbonyl compounds in order to regenerate the NADH. For wider applicability in industrial usage of FDH, there is a demand for higher stability of the enzyme. We report here the overexpression in Escherichia coli and subsequent characterization of FDH from thermophilic fungus Chaetomium thermophilum (C t FDH ) . Ct FDH was found to be more acidic than the typical FDHs from various sources, having its optimum at pH 5, and it also showed moderate thermostability at pH 5. The modelling of the enzyme and formate in the active site indicated that the enzyme functions with metal-independent hydride shift in the same way as the other NAD + -dependent FDHs of this enzyme group. Dimer interface properties were also analyzed. Ct FDH shows potential being a template for engineering higher thermostability for applications in acidic conditions. [ABSTRACT FROM AUTHOR]