Plantaricins - biosynthesis, mode of action and potential in ensuring food safety

Scharakteryzowano właściwości, strukturę oraz spektrum aktywności plantarycyn wytwarzanych przez niektóre szczepy Lactobacillus. Przedstawiono ich klasyfikację, mechanizm biosyntezy, modele działania na inne bakterie oraz stabilność. Plantarycyny są dość różnorodne pod względem właściwości fizykochemicznych, struktury i spektrum aktywności przeciwdrobnoustrojowej. Szczepy Lactobacillus plantarum zdolne do syntezy plantarycyn należą do mikroorganizmów najczę- ściej obecnych w fermentowanych produktach spożywczych, a także w napojach i innych wyrobach z dodatkiem mleka. Budowa cząsteczek, ich stabilność oraz mechanizm działania sprawiają, że plantary- cyny charakteryzują się skutecznym działaniem bakteriobójczym. Ze względu na niewielką oporność organizmów patogennych na te substancje mogą być one alternatywą dla wielu stosowanych obecnie związków o działaniu przeciwdrobnoustrojowym. Plantarycyny wpływają na zahamowanie wzrostu drob- noustrojów chorobotwórczych, a w konsekwencji na poprawę zdrowia człowieka. Z uwagi na coraz więk- sze zainteresowanie produktami naturalnymi plantarycyny mogą w przyszłości znaleźć zastosowanie w różnych gałęziach przemysłu. Wyniki badań dotyczące ich wykorzystania mogą stać się podstawą do projektowania efektywnych preparatów probiotycznych, kultur starterowych do produkcji fermentowanej żywności czy nowych metod zabezpieczania żywności, co w konsekwencji wpłynie na poprawę zdrowia i jakości życia człowieka

Isozyme polymorphism and genetic variation of selected partial populations of Istebna spruce [Picea abies [L.] Karst]

The genetic structure of Norway spruce [Picea abies (L.) Karst] of the Istebna race was studied in two populations from the Carpathian seed stands in the Malinka and Czarne Forestries. The recent provenance test results have shown a high quality of both populations. The results were compared with the genetic variation parameters calculated for the selected seed stand from the Bukowiec Forestry (compartment 149h), whose genetic structure in the progeny test for this species is considered a national standard. Five enzyme systems were analysed. The results show that the mean number of alleles per locus and the heterozygosity observed in the analysed populations are greater than those reported in the literature for other natural Norway spruce populations from the Carpathians. The heterozygosity level of the studied seed stands was higher than of the selective population of the Istebna spruce plus trees and the level of genetic diversity was similar to that of the Bukowiec seed stands. Thus, it can be concluded that the analysed seed stands from Czarne and Malinka, compartment 91h can be used as a supplementary seed base. However, at the individual partial population level, the Bukowiec spruce population, compartment 149h is considered to be of the highest value

Isoenzyme polymorphism of Norway spruce of the Istebna and Tarnawa race and selected provenances tested in IPTNS-IUFRO 1964/68 trial in Krynica

In this study the genetic structure of Istebna and Tarnawa plus trees was studied and polymorphism of twenty four provenances of spruce tested in a IPTNS−IUFRO 1964/68 site in Krynica representing selected regions of the species occurrence was analyzed. The genetic diversity was estimated with seven isoenzyme systems encoded in eleven loci. The highest genetic polymorphism was shown by plus trees of the Istebna and Tarnawa race and the lowest by spruce from IUFRO experiment. There was a statistically significant effect of origin on the mean number of alleles per locus. The origin of the analyzed trees had no effect on other parameters of genetic variability: the effective number of alleles per locus, observed and expected heterozygosity and Wright index

Increased viability of probiotic Lactobacillus rhamnosus after osmotic stress

The objective of this work was to assess the impact of various NaCl concentrations on Lactobacillus rhamnosus OXY viability after freeze-drying. Osmotic stress was applied during the exponential growth phase of bacterial culture. At salt concentrations between 0.2–0.5 M, a high biomass concentration and a significant increase in cell viability after lyophilisation was observed. An analysis of two-dimensional protein gels indicated the presence of shock proteins, for example, GroEL, ClpB, DnaK, TF, which provide resistance during freeze-drying and subsequent storage. On the basis of these results, it is recommended that lactic acid bacteria cultures be sub-lethally treated with 0.5 M NaCl before freeze-drying

Optimization of mutanase production by Trichoderma harzianum

The present paper describes optimization of fermentation conditions in shaken flasks and scale-up of fermentor production up to 115 L. The response surface methodology (RSM) has been successfully applied in standardization of mutanase production by Trichoderma harzianum CCM F-340. The model was very well fitted to the experimental data and explained more than 96% of the whole variation of the response (adjusted R2 = 0.962). In order to confirm the adequacy of the regression model based on the experimental data, validation cultures were grown in conditions created through optimization. The highest enzyme activity (0.747 U/mL) was reached in shaken flask cultures on Mandels’ medium in a volume of 140 mL modified in terms of carbon (cell wall preparation from the polypore fungus Laetiporus sulphureus 8.08 g/L) and nitrogen (soybean peptone 1.38 g/L) sources, under culture conditions 30°C, pH 5.3, agitation 270 rpm. The scale-up of the culture in the bioreactors with a working volume of 5 and 115 L resulted in a slight decrease in the mutanase activity (0.734 and 0.682 U/mL, respectively). The validation experiment showed a 70.6% increase in the production of mutanase compared with the culture before optimization. The results proved that the cultures could be scaled-up successfully from shaken flasks to the bioreactor scale. Our results indicate that in optimal conditions, T. harzianum could be a highly effective extracellular mutanase source. This report is the first to deal with optimization of mutanase biosynthesis using a mathematical model and scale-up of enzyme production in controlled fermentors with a view to facilitate application thereof in industry.Keywords: Mutanase, Trichoderma harzianum, response surface methodology (RSM), bioreactors, submerged culture.African Journal of Biotechnology, Vol 13(25) 2538-254

Production of exopolysaccharides by a probiotic strain of Lactobacillus rhamnosus: Biosynthesis and purification methods

The ability to produce exocellular polysaccharides is widespread among lactic acid bacteria; however, only some strains produce both capsular polysaccharides (CPS) and exopolysaccharides (EPS). The increasing demand for novel synbiotic products requires a search for new probiotic EPS-producing strains. In this work, we provide evidence that Lactobacillus rhamnosus E/N is capable of producing both forms of polysaccharides when grown in MRS broth. CPS surrounding the bacterial surface was observed by optical microscopy and transmission electron microscopy. EPS present in the growth medium was produced mainly during the exponential growth phase. CPS and EPS were extracted from the culture of Lb. rhamnosus E/N with yields of 12.6 mg l−1 and 146 mg l−1, respectively. It was shown that the method used to isolate the EPS fraction exerted a strong influence on the final amount of EPS obtained. In this study, we propose the most effective method of extraction of EPS from Lb. rhamnosus cultures. Lb. rhamnosus E/N could be considered for potential technological application as a probiotic for use in improving the properties of new pharmaceutical products

The Plackett-Burman design in optimization of media components for biomass production of Lactobacillus rhamnosus OXY

The central composite design was developed to search for an optimal medium for the growth of Lactobacillus rhamnosus OXY. The effect of various media components, such as carbon sources, simple and complex nitrogen sources, mineral agents, and growth factors (vitamins B, amino acids) was examined. The first-order model based on Plackett-Burman design showed that glucose, sodium pyruvate, meat extract and mineral salts significantly influenced the growth of the examined bacteria. The second-order polynomial regression confirmed that maximum biomass production could be achieved by the combination of glucose (12.38 g/l), sodium pyruvate (3.15 g/l), meat extract (4.08 g/l), potassium phosphate (1.46 g/l), sodium acetate (3.65 g/l) and ammonium citrate (1.46 g/l).The validation of the predicted model carried out in bioreactor conditions confirmed the usefulness of the new medium for the culture of L. rhamnosus OXY in large scale. The optimal medium makes the culture of the probiotic bacterium L. rhamnosus OXY more cost effective