Metabolic engineering of Saccharomyces cerevisiae for enhanced taxadiene production.

BACKGROUND: Metabolic engineering enables the sustainable and cost-efficient production of complex chemicals. Efficient production of terpenes in Saccharomyces cerevisiae can be achieved by recruiting an intermediate of the mevalonate pathway. The present study aimed to evaluate the engineering strategies of S. cerevisiae for the production of taxadiene, a precursor of taxol, an antineoplastic drug. RESULT: SCIGS22a, a previously engineered strain with modifications in the mevalonate pathway (MVA), was used as a background strain. This strain was engineered to enable a high flux towards farnesyl diphosphate (FPP) and the availability of NADPH. The strain MVA was generated from SCIGS22a by overexpressing all mevalonate pathway genes. Combining the background strains with 16 different episomal plasmids, which included the combination of 4 genes: tHMGR (3-hydroxy-3-methylglutaryl-CoA reductase), ERG20 (farnesyl pyrophosphate synthase), GGPPS (geranyl diphosphate synthase) and TS (taxadiene synthase) resulted in the highest taxadiene production in S. cerevisiae of 528 mg/L. CONCLUSION: Our study highlights the critical role of pathway balance in metabolic engineering, mainly when dealing with toxic molecules like taxadiene. We achieved significant improvements in taxadiene production by employing a combinatorial approach and focusing on balancing the downstream and upstream pathways. These findings emphasize the importance of minor gene expression modification levels to achieve a well-balanced pathway, ultimately leading to enhanced taxadiene accumulation.

Decolorization of reactive blue 13 by Sporotrichum sp. and cytotoxicity of biotreated dye solution.

Wastewater from the textile industry contaminated with azo dyes affects the environment negatively, causes pollution, and threatens environmental balance. Among various methods for wastewater treatment, bioremediation emerges as an environmentally friendly, economical, and sustainable solution. In this study, white-rot fungus Sporotrichum sp. was employed to decolorize reactive blue 13 (RB13). The long-term decolorization capacity of the fungus was investigated by a sequential batch experiment under optimized conditions. The fungus showed high decolorization efficiency upon repeating usage, and its decolorization efficiency decreased from 97.4% to 87.09% after transferring to a freshly prepared medium seven times. The MTT (3-(4, 5-dimethylthiazolyl-2)-2, 5-diphenyltetrazolium bromide) assay) method using Chinese Hamster Lung V79 379A was performed to assess the cytotoxicity of treated water samples. This study revealed that Sporotrichum sp. has short-term enzymatic and long-term biosorption capacity on reactive blue 13 and the decolorization potential of the alive and dead cells is impressively high. PRACTITIONER POINTS: White-rot fungus Sporotrichum sp. is able to decolorize sulfonated azo-dye reactive blue 13 upon sequential incubation in freshly prepared dye solution. The decolorization mechanism of the fungus is estimated to be bioadsorption. Sporotrichum sp. can be considered for long-term usage and immobilization applications.

Gut Microbiome Alteration after Reboxetine Administration in Type-1 Diabetic Rats.

Antidepressants are drugs commonly used in clinical settings. However, there are very limited studies on the effects of these drugs on the gut microbiota. Herein, we evaluated the effect of reboxetine (RBX), a selective norepinephrine (noradrenaline) reuptake inhibitor (NRI), on gut microbiota in both diabetic and non-diabetic rats. This is the first report of relation between reboxetine use and the gut microbiota to our knowledge. In this study, type-1 diabetes induced by using streptozotocin (STZ) and RBX was administered to diabetic rats and healthy controls for 14 days. At the end of the treatment, stool samples were collected. Following DNA extraction, amplicon libraries for the V3-V4 region were prepared and sequenced with the Illumina Miseq platform. QIIME was used for preprocessing and analysis of the data. As a result, RBX had a significant effect on gut microbiota structure and composition in diabetic and healthy rats. For example, RBX exposure had a pronounced microbial signature in both groups, with a low Firmicutes/Bacteroidetes ratio and low Lactobacillus levels. While another abundance phylum after exposure to RBX was Proteabacteria, other notable taxa in the diabetic group included Flavobacterium, Desulfovibrionaceae, Helicobacteriaceae, Campylobacterales, and Pasteurellacae when compared to the untreated group.

Synthesis and biological evaluation of pyrazoline derivatives bearing an indole moiety as new antimicrobial agents.

1-(p-Methylphenyl)-3,5-diaryl-2-pyrazoline derivatives (2a-f) were synthesized via the treatment of 1-(1H-indol-3-yl)-3-aryl-2-propen-1-ones (1a-f) with p-methylphenylhydrazine hydrochloride in hot acetic acid. The structures of these compounds were elucidated by IR, ¹H NMR, and mass spectral data and elemental analysis. These compounds were investigated for their antimicrobial activity. Brine-Shrimp lethality assay was carried out to determine the toxicity of the compounds. Compound 2e, which is the pyrazoline derivative bearing the 2,5-dichlorophenyl moiety, can be identified as the most promising agent against Klebsiella pneumoniae (ATCC 13883) and Candida glabrata (ATCC 36583) due to its inhibitory effects on K. pneumoniae and C. glabrata with a MIC value of 100 µg/mL as a non-toxic agent (LC50 > 1000 µg/mL).

Synthesis and antimicrobial activity of some new hydrazone-bridged thiazole-pyrrole derivatives.

In this work, we synthesized fourteen different compounds which contain hydrazone bridged thiazole and pyrrole rings. For this purpose, pyrrole-2-carboxaldehydes were reacted directly with thiosemicarbazide in ethanol and then obtained thiosemicarbazones were condensed with α-bromoacetophenone derivatives (Hantzsch reaction) to give 1-substituted pyrrole-2-carboxaldehyde [4-(4-substituted phenyl)-1,3-thiazol-2-yl] hydrazones. The structures of the obtained compounds were elucidated by using IR, (1)H-NMR and FAB(+)-MS spectral data and elemental analyses results. All of the compounds were screened for their antibacterial and antifungal activities against twelve different microorganisms by using microbroth dilution method. Ketoconazole and chloramphenicol were used as standard drugs. All of the compounds showed good activity against Staphylococcus aureus and Enterococcus faecalis.

Antimicrobial activity of a new series of benzimidazole derivatives.

Due to antimicrobial importance of benzimidazoles and hydrazones, some benzimidazole-hydrazone compounds were synthesized to screen their antimicrobial activity. Structures of the synthesized compounds were elucidated by (1)H-NMR, IR and ES-MS spectral data and elemental analysis. The synthesized benzimidazole-hydrazones exhibited very weak antibacterial activity. However, antifungal activity of some of the synthesized compounds was very notable against Candida species. The compounds displaying important antifungal activity were screened for their toxicity. Artemia salina 96-well assay was used to determine cytotoxicity of the compounds. Tested compounds exhibited toxicity to different extents (LD(50) = 126.33-368.72 µg/mL). Nevertheless, determination of 3-14 folds higher LD(50) than minimum inhibitory concentration is a significant finding, which demonstrates that the compounds display antifungal activity at non-toxic concentration.

Antimicrobial activity of a new combination system of benzimidazole and various azoles.

In the present study a new series of benzimidazole derivatives bearing various (benz)azolylthio moieties were synthesized so as to investigate their antimicrobial activity. Structures of the target compounds (5a-5i) were confirmed by their IR, (1) H-NMR, ES-MS spectral data, and elemental analyses. The synthesized compounds (5a-5i) exhibited poor activity against bacterial strains. On the other hand, antifungal activity of the compounds against Candida species was very significant. Brine-Shrimp lethality assay was performed for determination of toxicity of the compounds. Compounds 5a, 5c, and 5d were evaluated as non-toxic in addition to their attractive antifungal activity. However, the other compounds (5b, e-i) in the series showed toxicity to different extents.

Antimicrobial activity and a SAR study of some novel benzimidazole derivatives bearing hydrazone moiety.

In this study 12 novel benzimidazole compounds bearing hydrazone moiety were synthesized in order to investigate their possible antibacterial and antifungal activity. Structures of the synthesized compounds were elucidated by spectral data. Six different gram-negative and four different gram-positive bacterial strains were used in antibacterial activity tests. Antifungal activity tests were also performed against three different fungal strains. Most of the test compounds found to be significantly effective against Proteus vulgaris, Staphylococcus typhimurium, Klebsiella pneumoniae and Pseudomonas aeruginosa gram-negative bacterial strains. A structure-activity relationship (SAR) study including some electronic parameters was carried out and a connection between antibacterial activity and electronic properties of the target compounds was determined. Toxicity of the most effective compounds was established by performing Brine-Shrimp lethality assay.