Introduction: Application of lactic acid bacteria for synthesis of silver (AG) nanoparticles (NPs) could be a good ecological friendly alternative to chemical and physical methods. The objective of this study was to investigate the biosynthesis of silver NPs using Lactobacillus strains and to compare their monosaccharide composition of capsular exopolysaccharides and the antibacterial activity of synthesized nanoparticles. Methods: The washed cells of 22 Lactobacillus strains were used for in vitro silver nanoparticle biosynthesis from silver nitrate solution. The NPs formation was confirmed by UV-visible spectroscopy and transmission electron microscopy (TEM) analysis. TEM micrographs were used for the evaluation of NPs size. The monosaccharide composition of capsular exopolysaccharides was determined using GC/MS analysis. The antimicrobial activity was determined by agar well diffusion assay. Results: The capsular layers of Lactobacillus strains contained heteropolysaccharides that were composed mostly of glucose, mannose, galactose and rhamnose in a different molar ratio. It was found that Ag NPs with large size (30.65 ± 5.81 nm) obtained from L. acidophilus 58p were more active against S. epidermidis, E. coli, K. pneumonia,S. flexneri and S. sonnei compared with Ag NPs from L. plantarum 92T (19.92 ± 3.4 nm). Conclusion: The size and antibacterial activities of Ag NPs were strain-dependent and such characteristics may be due to the capsular biopolymer composition of Lactobacillus strains used for Ag NPs synthesis.

This study was carried out to select the bacteriocinogenic strains among Enterococcus strains isolated from Ukrainian traditional dairy products using a low-cost media for screening, that containing molasses and steep corn liquor. A total of 475 Enterococcus spp. strains were screened for antagonistic activity against Pseudomonas aeruginosa, Escherichia coli, Staphylococcus aureus, and Listeria monocytogenes indicator strains. The initial screening revealed that 34 Enterococcus strains during growth in low-cost medium containing corn steep liquor, peptone, yeast extract, and sucrose produced metabolites with inhibition activity against at least of the indicator strains used. Enterocin genes entA, entP, and entB were detected in 5 Enterococcus strains by PCR assay. Genes of enterocins A and P were found in E. faecalis 58 and Enterococcus sp. 226 strains, enterocins B and P – in Enterococcus sp. 423, enterocin A – in E. faecalis 888 and E. durans 248 strains. Bacteriocin-like inhibitory substances (BLIS) produced by these Enterococcus strains were thermostable and sensitive to proteolytic enzymes. To our knowledge, this is the first report on the isolation of enterocin-producing wild Enterococcus strains from traditional Ukrainian dairy products using a low-cost media for screening bacteriocinogenic strains. Strains E. faecalis 58, Enterococcus sp. 423, and Enterococcus sp. 226 are promising candidates for practical use as producers of bacteriocins with inhibitory activity against L. monocytogenes using molasses and steep corn liquor as cheap sources of carbon and nitrogen, that can significantly reduce the cost of industrial bacteriocin production. Further studies will be required to determine the dynamic of bacteriocin production, its structure, and mechanisms of antibacterial action.

Mannan sulphates (MS), obtained by sulphatation of extracellular linear mannan (LM) from Rhodotorula rubra, induced resistance to tobacco mosaic virus (TMV) in hypersensitive plants, retained in isolated protoplasts. MS‐induced resistance in tobacco is accompanied by a marked increase of lytic processes in cells and a decrease of total (acidic and alkaline) protein content. In addition to this, new protein components, including PR‐proteins and antiviral substances, of the inhibitor of virus replication (IVR) type, appeared in treated plant tissues. MS‐induced resistance resembles localized resistance induced by TMV in hypersensitive tobacco plants and could serve as an experimental model for study of the latter.

Мета. Охарактеризувати взаємодію клітин штаму Lactobacillus plantarum 337Д УКМ В-2627, що володіє пробіотичними властивостями, з каолінітом й монтморилонітом. Методи. Використано методи інфрачервоної спектроскопії, трансмісійної електронної мікроскопії, адсорбційно-структурний статичний об'ємний метод, мікробіологічні та статистичні методи. Результати. При взаємодії клітин штаму L. plantarum 337Д з частинками глинистих мінералів характеристики пористого простору останніх практично не змінювались у порівнянні з вихідними зразками, розподіл пор за розмірами ставав ширшим за рахунок появи пор великого діаметру, зменшувалась питома поверхня, але сорбційна ємність та шарова будова глинистих мінералів зберігалась. Вперше встановлено вплив каолініту і монтморилоніту на ріст штаму L. plantarum 337Д in vitro. Найбільший стимулювальний вплив глинистих мінералів спостерігали на другій годині культивування. Питома швидкість росту штаму L. plantarum 337Д була у 5,2 рази більшою при культивуванні в середовищі MRS з 4 % каолініту та у 6 разів більшою-в середовищі MRS з 1 % монтморилоніту в порівнянні з контролем. Наявність у середовищі каолініту чи монтморилоніту уповільнювала процес зниження рН при культивуванні штаму L. plantarum 337Д порівняно з контролем. За наявності монтморилоніту рН середовища знижувався повільніше, ніж у присутності каолініту. Різниця між значенням рН середовища з 4 % каолініту на початку культивування і через дві години (∆рН) була в 10 разів меншою в порівнянні з контролем. У той же час рН середовищ з 1 % і 4 % монтморилоніту починав знижуватись через 4 години культивування. Висновки. Різний вплив на ріст штаму L. plantarum 337Д обумовлений відмінностями фізико-хімічних характеристик каолініту і монтморилоніту, використаних у роботі. К л ю ч о в і с л о в а: молочнокислі бактерії, алюмосилікати, каолініт, монтморилоніт.

Cellular fatty acids composition is an important chemotaxonomic characteristic of bacterial cells. At the same time cellular fatty acids play a key role in maintaining the viability of micro-organisms in different environmental conditions. In this study, intraspecies heterogeneity of cellular fatty acids composition of Lactobacillus plantarum strains was examined. This work provides novel and important information about a relationship between cellular fatty acids composition of Lact. plantarum strains and source of isolation or stress resistance profile. Our results showed that cellular fatty acids composition is quite diverse among Lact. plantarum strains derived from different sources and may reflect previous cell's history. Our findings should be considered in chemotaxonomic studies of lactic acid bacteria and its ecology.