From spores to fungal pellets: A new high-throughput image analysis highlights the structural development of Aspergillus niger. Biotechnology and bioengineering Many filamentous fungi are exploited as cell factories in biotechnology. Cultivated under industrially relevant submerged conditions, filamentous fungi can adopt different macromorphologies ranging from dispersed mycelia over loose clumps to pellets. Central to the development of a pellet morphology is the agglomeration of spores after inoculation followed by spore germination and outgrowth into a pellet population, which is usually very heterogeneous. As the dynamics underlying population heterogeneity is not yet fully understood, we present here a new high-throughput image analysis pipeline based on stereomicroscopy to comprehensively assess the developmental program starting from germination up to pellet formation. To demonstrate the potential of this pipeline, we used data from 44 sampling times harvested during a 48 h submerged batch cultivation of the fungal cell factory Aspergillus niger. The analysis of up to 1700 spore agglomerates and 1500 pellets per sampling time allowed the precise tracking of the morphological development of the overall culture. The data gained were used to calculate size distributions and area fractions of spores, spore agglomerates, spore agglomerates within pellets, pellets, and dispersed mycelia. This approach eventually enables the quantification of culture heterogeneities and pellet breakage. 10.1002/bit.28124

The transcription factor Cas5 suppresses hyphal morphogenesis during yeast-form growth in Candida albicans. Kim Jong-Myeong,Moon Hye Yun,Lee Dong Wook,Kang Hyun Ah,Kim Jeong-Yoon Journal of microbiology (Seoul, Korea) Candida albicans is an opportunistic human pathogen that exists as yeast, hyphal or pseudohyphal forms depending on pH, nutrients, and temperature. The morphological transition from yeast to hyphae, which is required for the complete virulence of C. albicans, is controlled by many transcription factors that activate or repress hypha-specific genes. The C. albicans transcriptional factor Cas5, a key regulator of genes involved in cell wall integrity, affects the susceptibility of C. albicans to fluconazole, an inhibitor of ergosterol synthesis. In this study, we found that deletion of CAS5 in C. albicans decreased the expression levels of a set of ergosterol biosynthesis genes, such as ERG2, ERG3, ERG5, ERG6, ERG11, and ERG24, resulting in the accumulation of lanosterol and zymosterol, which are intermediate metabolites in the ergosterol biosynthesis pathway. Interestingly, it was observed that the cas5Δ/Δ mutant could not maintain the yeast form under non-hypha-inducing conditions, while the CAS5-overexpressing cells could not form hyphae under hypha-inducing conditions. Consistent with these observations, the cas5Δ/Δ mutant highly expressed hypha-specific genes, ALS3, ECE1, and HWP1, under non-hypha-inducing conditions. In addition, CAS5 transcription was significantly downregulated immediately after hyphal initiation in the wild-type strain. Furthermore, the cas5Δ/Δ mutant reduced the transcription of NRG1, which encodes a major repressor of hyphal morphogenesis, while Cas5 overexpression increased the transcription of NRG1 under hypha-inducing conditions. Collectively, this study suggests the potential role of Cas5 as a repressor of hypha-specific genes during yeast-form growth of C. albicans. 10.1007/s12275-021-1326-y

Efficient Enzyme-Assisted Extraction and Conversion of Polydatin to Resveratrol From Using Thermostable Cellulase and Immobilized β-Glucosidase. Frontiers in microbiology Resveratrol, a bioactive compound in high quantities in , has well-known health benefits. However, it mainly exists in its glycosidic form, polydatin, in plants. To increase the production of resveratrol for various uses in medicine, foods, and cosmetics, an efficient deglycosylation technique is needed for converting polydatin into resveratrol. We screened a new cellulolytic strain of from herb compost, and we optimized parameters within the fermentation process using response surface methodology with a Box-Behnken design. The yield of cellulase reached 2701.08 U/L, corresponding to values that were 5.4 times as high as those under unoptimized conditions. The cellulase possessed good thermostablity and was stable under both acidic and neutral conditions. The cellulase was then used in the pretreatment of root. After incubation at 50°C for 4 h with shaking at 150 rpm, the contents of piceid and resveratrol were determined to be 7.60 ± 0.15 and 9.72 ± 0.29 mg/g, respectively. To obtain complete deglycosylation, immobilized β-glucosidase (bgl2238) was added to the cellulase-treated extracts of root to convert residual polydatin into resveratrol. After the first cycle, the contents of piceid and resveratrol were determined to be 0 and 13.69 ± 0.30 mg/g, respectively. Moreover, enzyme activity showed little loss during up to 4 consecutive cycles. These results demonstrated that the immobilized β-glucosidase possessed high deglycosylation activity and outstanding operational stability. The mixture of cellulase and immobilized bgl2238 appears promising as a means to increase the supply of resveratrol in the medicine market worldwide. 10.3389/fmicb.2019.00445

Modification of a cellulase system by engineering Penicillium oxalicum to produce cellulose nanocrystal. Yang Tiantian,Guo Yingjie,Gao Na,Li Xuezhi,Zhao Jian Carbohydrate polymers In this study, three endoglucanases (EGs; Cel7B, Cel5B, and Cel12A), one cellobiohydrolase (CBH), and two auxiliary proteins (swollenin: SWO1 and SWO4) were used to hydrolyze microcrystalline cellulose (MCC) for cellulose nanocrystal (CNC) preparation. The mixture experiment of the three EGs showed that high CNC yield was obtained when the ratio of Cel7B and Cel5B is 1:1.11 (protein weight). Moreover, the addition of CBH (1 mg/g) and SWO1 from Trichoderma reesei effectively increased the yield of CNC. On the basis of the results, the cellulase-producing strain of Penicillium oxalicum M12 was engineered to improve its cellulase system. An engineered strain of cEES performed well in CNC preparation. CNC with a yield of 11.79 % and a crystallinity of 83.85 % were produced using the crude enzyme from cEES as a means to hydrolyze MCC, and the size and shape of CNC were uniform and fusiform. 10.1016/j.carbpol.2020.115862