authors declare that they have no conflicts of interest with the contents of this article. This article contains Tables S1 and S2, Figs. S1-S14, and Text S1-S3. Raw whole-transcriptome shotgun sequencing data have been submitted to the NCBI SRA website with BioProject ID PRJNA526091.
BackgroundThe filamentous fungus Trichoderma reesei Rut-C30 is one of the most vital fungi for the production of cellulases, which can be used for biofuel production from lignocellulose. Nevertheless, the mechanism of transmission of external stimuli and signals in modulating cellulase production in T. reesei Rut-C30 remains unclear. Calcium is a known second messenger regulating cellulase gene expression in T. reesei.ResultsIn this study, we found that a biologically relevant extracellular Mn2+ concentration markedly stimulates cellulase production, total protein secretion, and the intracellular Mn2+ concentration of Rut-C30, a cellulase hyper-producing strain of T. reesei. Furthermore, we identified two Mn2+ transport proteins, designated as TPHO84-1 and TPHO84-2, indicating that they are upstream in the signaling pathway that leads to cellulase upregulation. We also found that Mn2+ induced a significant increase in cytosolic Ca2+ concentration, and that this increased cytosolic Ca2+ might be a key step in the Mn2+-mediated regulation of cellulase gene transcription and production. The utilization of LaCl3 to block plasma membrane Ca2+ channels, and deletion of crz1 (calcineurin-responsive zinc finger transcription factor 1) to interrupt calcium signaling, showed that Mn2+ exerts the induction of cellulase genes via calcium channels and calcium signaling. To substantiate this, we identified a Ca2+/Mn2+ P-type ATPase, TPMR1, which could play a pivotal role in Ca2+/Mn2+ homeostasis and Mn2+ induction of cellulase genes in T. reesei Rut-C30.ConclusionsTaken together, our results revealed for the first time that Mn2+ stimulates cellulase production, and demonstrates that Mn2+ upregulates cellulase genes via calcium channels and calcium signaling. Our research also provides a direction to facilitate enhanced cellulase production by T. reesei.Electronic supplementary materialThe online version of this article (10.1186/s13068-018-1055-6) contains supplementary material, which is available to authorized users.
Objectives: The World Health Organization (WHO) proposed the Integrated Care for Older People (ICOPE) screening tool to identify older people with priority conditions associated with declines in intrinsic capacity (IC). We aimed to determine the clinical utility of the WHO ICOPE screening tool in a Chinese population.Method: A total of 376 adults aged 68.65 ± 11.41 years participated in the study. IC was assessed with the WHO ICOPE screening tool, covering five domains: cognitive, locomotor, sensory, vision, and psychological capacity. We assessed the activities of daily living (ADL); instrumental activities of daily living (IADL); the Fried frailty phenotype; FRAIL scale; Strength, Assistance With Walking, Rising From chair, Climbing Stairs, and Falls (SARC-F) scale; Mini-mental State Examination (MMSE); Geriatric Depression Scale (GDS); social frailty; and quality of life.Results: There were 260 (69.1%) participants who showed declines in one or more IC dimensions. The percentages of decline in mobility, cognition, vitality, hearing, vision, and psychological capacity were 25.3, 46.8, 16.2, 15.4, 11.7, and 12.0%, respectively. IC decreased with increasing age. After adjusting for age, sex, and multimorbidity, participants with declines in IC were more likely to be older, frail, and disabled. They also had worse physical, mental, and overall health. There was a higher prevalence of declines in IC in participants with frailty. After adjusting for age, IC was positively correlated with walking speed, resilience score, and MMSE score and negatively correlated with frailty, SARC-F score, IADL score, GDS score, and physical and mental fatigue. The IC score was not associated with body composition variables such as fat-free mass, body fat percentage, or visceral fat area. Higher IC was associated with better quality of life. The area under the curve of the receiver operating characteristic (AUC-ROC) for the ICOPE screening tool vs. Fried phenotype, FRAIL, ADL disability, IADL disability, and SARC-F were 0.817, 0.843, 0.954, 0.912, and 0.909, respectively.Conclusion: Our research affirms that the ICOPE screening tool is useful to identify adults with poor physical and mental function in a Chinese sample. This tool may assist in identifying declines in IC in an integrative care model and help slow down function decline and onset of care dependence.
Background The filamentous fungus Trichoderma reesei produces cellulase enzymes that are widely studied for lignocellulose bioconversion to biofuel. N , N -dimethylformamide (DMF) is a versatile organic solvent used in large quantities in industries. Results In this study, we serendipitously found that biologically relevant concentrations of extracellular DMF-induced cellulase production in the T. reesei hyper-cellulolytic mutant Rut-C30 and wild-type strain QM6a. Next, by transcriptome analysis, we determined that plc - e encoding phospholipase C was activated by DMF and revealed that cytosolic Ca 2+ plays a vital role in the response of T. reesei to DMF. Using EGTA (a putative extracellular Ca 2+ chelator) and LaCl 3 (a plasma membrane Ca 2+ channel blocker), we demonstrated that DMF induced a cytosolic Ca 2+ burst via extracellular Ca 2+ and Ca 2+ channels in T. reesei , and that the cytosolic Ca 2+ burst induced by DMF-mediated overexpression of cellulase through calcium signaling. Deletion of crz1 confirmed that calcium signaling plays a dominant role in DMF-induced cellulase production. Additionally, 0.5–2% DMF increases the permeability of T. reesei mycelia for cellulase release. Simultaneous supplementation with 1% DMF and 10 mM Mn 2+ to T. reesei Rut-C30 increased cellulase activity approximately fourfold compared to that without treatment and was also more than that observed in response to either treatment alone. Conclusions Our results reveal that DMF-induced cellulase production via calcium signaling and permeabilization. Our results also provide insight into the role of calcium signaling in enzyme production for enhanced cellulase production and the development of novel inducers of cellulase. Electronic supplementary material The online version of this article (10.1186/s13068-019-1375-1) contains supplementary material, which is available to authorized users.
Background: The filamentous fungus Trichoderma reesei is a major workhorse employed to produce cellulase, which hydrolyzes lignocellulosic biomass for the production of cellulosic ethanol and bio-based products. However, the economic efficiency of biorefineries is still low. Results: In this study, the truncation of cellulase activator ACE3 was identified and characterized in T. reesei classical mutant NG14 and its direct descendants for the first time. We demonstrated that the truncated ACE3 is the crucial cause of cellulase hyper-production in T. reesei NG14 branch. Replacing the native ACE3 with truncated ACE3 in other T. reesei strains remarkably improves cellulase production. By truncating ACE3, we engineered a T. reesei mutant, PC-3-7-A723, capable of producing more cellulase than other strains. In a 30-L fermenter, fed-batch fermentation with PC-3-7-A723 drastically increased the maximum cellulase titer (FPase) to 102.63 IU/mL at 240 h, which constitutes a 20-30% improvement to that of the parental strain PC-3-7. Conclusions: This work characterized the function of truncated ACE3 and demonstrated that analysis of classical mutants allows rational engineering of mutant strains with improved cellulase production necessary to process lignocellulosic biomass. Our rational engineering strategy might be useful for enhancing the production of other bio-based products.
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