Oxidative stress response of Blakeslea trispora induced by H2O2 during β-carotene biosynthesis

Genome-Wide Identification, Phylogeny and Expressional Profiles of Mitogen Activated Protein Kinase Gene Family in Blakeslea trispora

In eukaryotes, the mitogen-activated protein kinase (MAPK) cascade pathway is a highly conserved cell signaling mechanism that is essential for stress response, growth, and development. MAPK cascade genes have currently been identified and characterized in a wide range of fungi, although they have not been fully understood in early divergent fungal lineages like the Mucoromycota, which contains Mucoromycotina, Glomeromycotina, and Mortierellomycotina. In this study, a genome-wide investigation of Blakeslea trispora (Mucorales, Choanephoraceae) revealed a total of 19 MAPK cascade genes, including 9 BtMAPKKKs, 4 BtMAPKKs, and 6 BtMAPKs genes. Using phylogenetic analysis, it was found that the kinase domain sequences and motif composition of the three MAPK, MAPKK, and MAPKKK lineages are substantially conserved in fungi. Whole genome duplication analysis indicated that B. trispora has four and nine duplication pairs in the MAPK and MAPKKK genes, respectively, which are expanded by segmental replication events. BtHog2, the orthologous protein of Hog1, exhibits a substantial rise in transcription levels under blue light irradiation, indicating its function in light signal response and transduction. Several sets of interacting protein pairs were found using molecular docking analysis and yeast two-hybrid assay, providing a comprehensive MAPK cascade signaling network in B. trispore. Furthermore, MAPK cascade proteins show varying transcription levels in response to blue light and sex hormone stimulation, as well as variable treatment duration. BtMAPKKK9 and BtBck1 are strongly induced during sexual interaction, indicating their involvement in the response to trisporic acid and the subsequent alterations in hyphal cell wall structure. These findings shed light on the evolution of MAPK cascade genes and the functional mechanisms underlying MAPK cascade genes in response to light and sex hormone signaling pathways in B. trispore.

Molecular Regulation of Carotenoid Accumulation Enhanced by Oxidative Stress in the Food Industrial Strain Blakeslea trispora

Blakeslea trispora is a key industrial strain for carotenoid production due to its rapid growth, ease of cultivation, and high yield. This study examined the effects of oxidative stress induced by rose bengal (RB) and hydrogen peroxide (H2O2) on carotenoid accumulation, achieving maximum yields of 459.38 ± 77.15 μg/g dry cell weight (DCW) at 0.4 g/L RB and 294.38 ± 14.16 μg/g DCW at 0.6% H2O2. These results demonstrate that oxidative stress promotes carotenoid accumulation in B. trispora. To investigate the underlying molecular mechanisms, transcriptional levels of key genes were analyzed under optimal stress conditions. In the carotenogenic pathway, only HMGR showed upregulation, while ACC, linked to fatty acid biosynthesis, remained unchanged. Within the mitogen-activated protein kinase (MAPK) pathway, FUS3 transcription increased under both stress conditions, MPK1 transcription rose only under H2O2 stress, and HOG1 exhibited no significant changes. Among heat shock proteins (HSPs), only HSP70 showed elevated transcription under H2O2 stress, while other HSP genes remained unchanged. These findings suggest that oxidative stress induced by RB and H2O2 enhances carotenoid accumulation in B. trispora through distinct regulatory pathways. This study provides valuable insights into stress-adaptive mechanisms and offers strategies to optimize carotenoid production in fungi.

Arts, cultural heritage, sciences, and micro-/bio-/technology: Impact of biomaterials and biocolorants from antiquity till today!

Nature has inspired and provided humans with ideas, concepts, and thoughts on design, art, and performance for millennia. From early societies when humankind often took shelter in caves, until today, many materials and colorants to express feelings or communicate with one another were derived from plants, animals, or microbes. In this manuscript, an overview of these natural products used in the creation of art is given, from paintings on rocks to fashionable dresses made from bacterial cellulose. Besides offering many examples of art works, the origin and application of various biomaterials and colorants are discussed. While many facets of our daily lives have changed over millennia, one certainty has been that humans have an intrinsic need to conceptualize and create to express themselves. Driven by technological advances in the past decades and in the light of global warming, new and often more sustainable materials and colorants have been discovered and implemented. The impact of art on human societies remains relevant and powerful.

ONE-SENTENCE SUMMARY

This manuscript discusses the use of biomaterials and biocolorants in art from a historical perspective, spanning 37,000 bc until today.

The Biosynthesis of Penicillin and Cephalosporin C are Regulated by ROS at Transcriptional Level

In a recent work we showed that, besides lovastatin, ROS also accumulate during the production phase in Pencillium chrysogenum and in Acremonium chrysogenum, and that these ROS regulate the biosynthesis of penicillin and cephalosporin C. In the present study, we investigated the level at which this positive regulation is exerted. Internal ROS levels were manipulated, i.e., increased or decreased, in the production phase of the respective fermentations. Penicillin production decreased by 51.2% when internal ROS concentration was diminished by 50%, while a 62% production increase was observed when ROS were increased (62%). Similarly, Cephalosporin production decreased (35%) with antioxidants and increased (54.1%) with exogenous ROS. Expression analysis of the respective pcbAB genes, encoding the non-ribosomal peptide synthetase enzymes, was performed. Results showed down regulation of these genes in fermentations with lower ROS content, and upregulation in the cultures with higher ROS content, in both species. This showed that ROS regulation of penicillin in P. chrysogenum and of cephalosporin C in A. chrysogenum, is exerted at transcriptional level. In silico analysis of the pcbAB gene promoters in both species, suggested that this regulation could be mediated by stress-response transcription factors like Yap1, SrrA and/or MsnA, and/or by the Hap complex.

Multilevel Regulation of Carotenoid Synthesis by Light and Active Oxygen in Blakeslea trispora

Although Blakeslea trispora has been used for industrial production of β-carotene, the effects of light and oxidative stress on its synthesis have not been fully clarified. The present study focuses on the effects of light and reactive oxygen species (ROS) on carotenoid synthesis and their multilevel regulation in B. trispora. Blue light significantly influenced the intracellular ROS levels, carotenoid contents, and transcription of carotenoid structural genes, while ROS levels were positively correlated with intracellular carotenoid contents and transcriptional levels of carotenoid structural genes. Blue light and ROS were both significant factors affecting carotenoid synthesis with a significant interaction between them. Irradiation by pulsed blue light and (or) addition of generating agents for active oxygen could partially compensate for the inhibition derived from the transcription inhibitor (dactinomycin) and translation inhibitor (cycloheximide) on the multilevel phenotype. Therefore, blue light and ROS act on the transcription and translation of carotenoid structural genes to promote the accumulation of carotenoid in B. trispora.

Oxidative Stress Induction Is a Rational Strategy to Enhance the Productivity of Antrodia cinnamomea Fermentations for the Antioxidant Secondary Metabolite Antrodin C

Antioxidant metabolites contribute to alleviating oxidative stress caused by reactive oxygen species (ROS) in microorganisms. We utilized oxidative stressors such as hydrogen peroxide supplementation to increase the yield of the bioactive secondary metabolite antioxidant antrodin C in submerged fermentations of the medicinal mushroom Antrodia cinnamomea. Changes in the superoxide dismutase and catalase activities of the cells indicate that ROS are critical to promote antrodin C biosynthesis, while the ROS production inhibitor diphenyleneiodonium cancels the productivity-enhancing effects of H2O2. Transcriptomic analysis suggests that key enzymes in the mitochondrial electron transport chain are repressed during oxidative stress, leading to ROS accumulation and triggering the biosynthesis of antioxidants such as antrodin C. Accordingly, rotenone, an inhibitor of the electron transport chain complex I, mimics the antrodin C productivity-enhancing effects of H2O2. Delineating the steps connecting oxidative stress with increased antrodin C biosynthesis will facilitate the fine-tuning of strategies for rational fermentation process improvement.

Enhanced Astaxanthin Production in Escherichia coli via Morphology and Oxidative Stress Engineering

Astaxanthin is a carotenoid of high commercial value because of its excellent antioxidative, anti-inflammatory, and anticancer properties. Here, we developed a novel strategy for improving the production of astaxanthin via morphology and oxidative stress engineering. First, we identified the morphology-/membrane- and oxidative stress-related genes, which should be knocked down, using the CRISPRi system. Deleting the morphology-/membrane-related genes (lpp and bamB) and the oxidative stress-related genes (uspE and yggE) generated longer and larger cells with higher reactive oxygen species (ROS) levels, thus enhancing the production of astaxanthin and decreasing cell growth. To not only improve cell growth but also obtain longer and larger cells with higher ROS levels, a complementary expression system using a temperature-sensitive plasmid was established. Complementarily expressing the morphology-/membrane-related genes (lpp and bamB) and the oxidative stress-related genes (uspE and yggE) further improved the production of astaxanthin to 11.92 mg/g dry cell weight in shake flask cultures.

Carotene production from waste cooking oil by Blakeslea trispora in a bubble column reactor: The role of oxidative stress

The oxidative stress induced by hydroperoxides and reactive oxygen species (ROS) during carotene production from waste cooking oil (WCO) and corn steep liquor (CSL) by the fungus Blakeslea trispora in a bubble column reactor was investigated. The specific activities of the intracellular enzymes superoxide dismutase (SOD) and catalase (CAT) as well as the micromorphology of the fungus were measured in order to study the response of the fungus to oxidative stress. The changes of the morphology of microorganism leaded to pellets formation and documented using a computerized image analysis system. As a consequence of the mild oxidative stress induced by hydroperoxides of WCO and ROS a significant increase in carotene production was obtained. The highest carotene concentration (980.0 mg/l or 51.5 mg/g dry biomass) was achieved in a medium consisted of CSL (80.0 g/L) and WCO (50.0 g/L) at an aeration rate of 5 vvm after 6 days of fermentation. In this case the carotenes produced consisted of β-carotene (71%), γ-carotene (26%), and lycopene (3%). The strong oxidative stress in the fungus caused a significant increase of γ-carotene concentration. Bubble column reactor is a useful fermentation system for carotene production in industrial scale.

Adaptive Responses to Oxidative Stress in the Filamentous Fungal Shiraia bambusicola

Shiraia bambusicola can retain excellent physiological activity when challenged with maximal photo-activated hypocrellin, which causes cellular oxidative stress. The protective mechanism of this fungus against oxidative stress has not yet been reported. We evaluated the biomass and hypocrellin biosynthesis of Shiraia sp. SUPER-H168 when treated with high concentrations of H₂O₂. Hypocrellin production was improved by nearly 27% and 25% after 72 h incubation with 10 mM and 20 mM H₂O₂, respectively, while the inhibition ratios of exogenous 20 mM H₂O₂ on wild S. bambusicola and a hypocrellin-deficient strain were 20% and 33%, respectively. Under exogenous oxidative stress, the specific activities of catalase, glutathione reductase, and superoxide dismutase were significantly increased. These changes may allow Shiraia to maintain normal life activities under oxidative stress. Moreover, sufficient glutathione peroxidase was produced in the SUPER-H168 and hypocrellin-deficient strains, to further ensure that S. bambusicola has excellent protective abilities against oxidative stress. This study creates the possibility that the addition of high H₂O₂ concentrations can stimulate fungal secondary metabolism, and will lead to a comprehensive and coherent understanding of mechanisms against oxidative stresses from high hydrogen peroxide concentrations in the filamentous fungal Shiraia sp. SUPER-H168.

In situ high-valued utilization and transformation of sugars from Dioscorea zingiberensis C.H. Wright for clean production of diosgenin

The industrial production of diosgenin in China generates a large amount of high-sugar wastes with low bioavailability, which causes serious pollution to the environment. In this study, a new clean and efficient process for the production of diosgenin was developed using sugars through in situ high-valued transformation. The sugar mixture from Dioscorea zingiberensis C.H. Wright contained abundant beneficial components. Nine typical microorganisms that produced intracellular products were evaluated. Saccharopolyspora spinosa was selected for recursive protoplast fusion to increase the spinosad yield by 46.3% compared with that of the wildtype. Diosgenin and spinosad co-production was conducted in a 100L bioreactor, with pH controlled by adding glucose. The biological oxygen demand of the effluent water decreased from 15,000mg/L to 450mg/L; hence, the proposed process is environment friendly.