Tomasz Czernecki

Enterobacter sp. LU1 as a novel succinic acid producer - co-utilization of glycerol and lactose.

Succinic acid is an important C4‐building chemical platform for many applications. A novel succinic acid‐producing bacterial strain was isolated from goat rumen. Phylogenetic analysis based on the 16S rRNA sequence and physiological analysis indicated that the strain belongs to the genus Enterobacter. This is the first report of a wild bacterial strain from the genus Enterobacter that is capable of efficient succinic acid production. Co‐fermentation of glycerol and lactose significantly improved glycerol utilization under anaerobic conditions, debottlenecking the utilization pathway of this valuable biodiesel waste product. Succinic acid production reached 35 g l−1 when Enterobacter sp. LU1 was cultured in medium containing 50 g l−1 of glycerol and 25 g l−1 of lactose as carbon sources.

The Ability of a Novel Strain Scheffersomyces (Syn. Candida) shehatae Isolated from Rotten Wood to Produce Arabitol

Arabitol is a polyalcohol which has about 70% of the sweetness of sucrose and an energy density of 0.2 kcal/g. Similarly to xylitol, it can be used in the food and pharmaceutical industries as a natural sweetener, a texturing agent, a dental caries reducer, and a humectant. Biotechnological production of arabitol from sugars represents an interesting alternative to chemical production. The yeast Scheffersomyces shehatae strain 20BM-3 isolated from rotten wood was screened for its ability to produce arabitol from L-arabinose, glucose, and xylose. This isolate, cultured at 28°C and 150 rpm, secreted 4.03 ± 0.00 to 7.97 ± 0.67 g/l of arabitol from 17-30 g/l of L-arabinose assimilated from a medium containing 20-80 g/l of this pentose with yields of 0.24 ± 0.00 to 0.36 ± 0.02 g/g. An optimization study demonstrated that pH 4.0, 32°C, and a shaking frequency of 150 rpm were the optimum conditions for arabitol production by the investigated strain. Under these conditions, strain 20BM-3 produced 6.2 ± 0.17 g/l of arabitol from 17.5 g/l of arabinose after 4 days with a yield of 0.35 ± 0.01 g/g. This strain also produced arabitol from glucose, giving much lower yields, but did not produce it from xylose. The new strain can be successfully used for arabitol production from abundantly available sugars found in plant biomass.

Comparative characterization of volatile profiles of French, Italian, Spanish, and Polish red wines using headspace solid-phase microextraction/gas chromatography-mass spectrometry

ABSTRACT The aim of the study was to investigate whether the wines produced in France, Italy, Spain, and Poland differ in composition of volatile compounds, and whether red wines from Poland can be distinguished from those of other European countries. Thirty-five aroma compounds belonging to several groups – 13 alcohols, 9 acids, 3 aldehydes, 7 esters, 2 ketones, and 1 volatile phenol – were identified in the examined wines. The proportions of volatile compounds in wines from the four selected countries were similar. Statistical analysis revealed significant differences between French, Italian, Spanish, and Polish wines for 3-methylbutan-1-ol, butane-2,3-diol, phenylmethanol, 2-phenylethanol, dodecan-1-ol, propane-1,2,3-triol, diethyl butanedioate, 3-hydroxybutan-2-one, and 4-ethylphenol. In addition, diethyl butanedioate distinguished Polish wines from the other wines. Hierarchical cluster analysis (HCA) showed that the Polish wines were well separated from the other wines.

The production of arabitol by a novel plant yeast isolate Candida parapsilosis 27RL-4

Abstract Polyalcohol arabitol can be used in the food and pharmaceutical industries as a natural sweetener, a dental caries reducer, and texturing agent. Environmental samples were screened to isolate effective yeast producers of arabitol. The most promising isolate 27RL-4, obtained from raspberry leaves, was identified genetically and biochemically as Candida parapsilosis. It secreted 10.42– 10.72 g l-1 of product from 20 g l-1 of L-arabinose with a yield of 0.51 - 0.53 g g-1 at 28°C and a rotational speed of 150 rpm. Batch cultures showed that optimal pH value for arabitol production was 5.5. High yields and productivities of arabitol were obtained during incubation of the yeast at 200 rpm, or at 32°C, but the concentrations of the polyol did not exceed 10 g l-1. In modified medium, with reduced amounts of nitrogen compounds and pH 5.5-6.5, lower yeast biomass produced a similar concentration of arabitol, suggesting higher efficiency of yeast cells. This strain also produced arabitol from glucose, with much lower yields. The search for new strains able to successfully produce arabitol is important for allowing the utilization of sugars abundant in plant biomass.