Conversion of byproduct from biodiesel production glycerol to high-value compounds is of great importance. Ethanol is considered a promising product of glycerol bioconversion. The methylotrophic thermotolerant yeast Ogataea (Hansenula) polymorpha is of great interest for this purpose as the glycerol byproduct contains methanol and heavy metals as contaminants, and this yeast utilizes methanol and is relatively resistant to heavy metals. Besides, O. polymorpha shows robust growth on glycerol and produces ethanol from various carbon sources. The thermotolerance of this yeast is an additional advantage, allowing increased fermentation temperature to 45-48°C, leading to increased rate of the fermentation process and a fall in the cost of distillation. The wild-type strain of O. polymorpha produces insignificant amounts of ethanol from glycerol (0.8 g/l). Overexpression of PDC1 coding for pyruvate decarboxylase enhanced ethanol production up to 3.1 g/l, whereas simultaneous overexpression of PDC1 and ADH1 (coding for alcohol dehydrogenase) led to further increase in ethanol production from glycerol. Moreover, the increased temperature of fermentation up to 45°C stimulated the production of ethanol from glycerol used as the only carbon source up to 5.0 g/l, which exceeds the data obtained by methylotrophic yeast strains reported so far.

Production of fuel ethanol is one of the possible ways to utilize crude glycerol, substantial amounts of which are produced by biodiesel industry. Earlier, we have described construction of the recombinant strains of methylotrophic thermotolerant yeast Ogataea polymorpha with simultaneous overexpression of the genes PDC1and ADH1, which produced increased amounts of ethanol from glycerol. In this work, we have further improved these strains by overexpression of genes involved either in oxidative (through dihydroxyacetone) or phosphorylative (through glycerol-3-phosphate) pathway of glycerol catabolism, as well as heterologous gene coding for glycerol transporter FPS1 from Komagataella phaffii (formerly, Pichia pastoris).Obtained recombinant strains produced up to 10.7 g/L of ethanol (with ethanol productivity 30 mg/g of biomass/hr and yield 132 mg/g of consumed glycerol) from pure glycerol and up to 3.55 g/L of ethanol (with ethanol productivity 11.6 mg/g of biomass/hr and yield 72.3 mg/g of consumed glycerol) from crude glycerol as a carbon source, which is approximately 15 times more relative to that of the O. polymorpha wild-type strain and 2.2 more relative to the earlier constructed strain.

The medicinal use of genus Drosera, as an important antitussive for different respiratory diseases, has been known for centuries. Many of extracts from carnivorous plants exhibit various antibacterial and antifungal activities. Naphthoquinones containing extracts from Drosera have antiviral, antibacterial, antifungal, aphrodisiac, antispasmodic, antileprosy, antisclerotic and anticancer properties. The aim of the present study was to detect antibacterial activity of Drosera rotundifolia against Gram-positive and Gram-negative bacteria by the testing of MIC. For the study six strains of microorganisms were selected and there were Gram-positive bacteria -Bacillus thuringiensis (CCM 19T), Clostridium perfringens (CCM 4991), and Listeria monocytogenes (CCM 4699), as well as and Gram-negative bacteria - Escherichia coli (CCM 3988), Salmonella enterica subsp. enterica (CCM 3807) and Yersinia enterocolitica (CCM 5671). Plant extracts were isolated from three plants of Drosera rotundifolia L. (S1, S2 and S3) in different time range. The most effective extract with MIC50 value of 17.07 μg.ml-1 was S3, while forMIC90 of 19.05 μg.ml-1 were extracts S2 and S3 exhibiting antimicrobial activity against Bacillus thuringiensis, Clostridium perfringens and Listeria monocytogenes. Extracts S1, S2 showed MIC50 value 25.53 μg.ml-1for all the microorganism tested, but S3 extract revealed the same antimicrobial activity against Yersinia enterocolitica, Salmonella enterica subsp. enterica and Escherichia coli. Extract S1 has MIC90 value of 27.14 μg.ml-1 against all the microorganism tested, but S2 and S3 shared the same MIC90 for Yersinia enterocolitica, Salmonella enterica subsp. enterica and Escherichia coli.

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