Antifungal activity of Saccharomyces cerevisiae and assessment of ochratoxigenic load on currants by means of Real Time PCR.

Currants are prone to contamination by ochratoxin during cultivation, processing and storage conditions. Saccharomyces cerevisiae is considered to be among the main species of grape yeast flora able to control antagonistic fungi. In this study, the potential of S. cerevisiae Y33 was investigated to inhibit the growth of several fungal species indigenous to the microbiota of grapes. Moreover, the efficacy of this yeast species was investigated to inhibit OTA by toxin producing fungi both in vitro and in situ. For this purpose thirty-five different fungal species, belonging to the genera Aspergillus, Penicillium, Cladosporium, Fusarium and Alternaria interacted in vitro with S. cerevisiae on Malt Extract agar plates, stored at 25 °C for 14 days. Results showed that the highest OTA producer A. carbonarius F71 was inhibited more than 99% from day 7, in contrast to A. niger strains that presented enhanced OTA production at day 14 due to interaction with S. cerevisiae Y33. Additionally, the antifungal potential of the selected yeast was also studied in situ on currants subjected to different treatments and stored at 25 °C for 28 days. Microbiological analysis was undertaken for the enumeration of the bacterial and fungal flora, together with OTA determination at 7 and 21 days. To quantify A. carbonarius on all treated currant samples, molecular analysis with Real Time PCR was employed. A standard curve was prepared with A. carbonarius DNA. The efficiency of the curve was estimated to 10.416, the slope to -3.312 and the range of haploid genome that could be estimated was from 1.05 to 105∙105. The amount of A. carbonarius DNA in all treated currants samples, where the fungus was positively detected, ranged from as low as 0.08 to 562 ng DNA/g currants. The antifungal activity of S. cerevisiae Y33 was observed in all studied cases, causing inhibition of fungal growth and OTA production.

Trichoderma virens Gl006 and Bacillus velezensis Bs006: a compatible interaction controlling Fusarium wilt of cape gooseberry.

The combination of Trichoderma virens Gl006 and B. velezensis Bs006 as a consortium has high potential to control Fusarium wilt (FW) of cape gooseberry (Physalis peruviana) caused by Fusarium oxysporum f. sp. physali (Foph). However, the interactions between these two microorganisms that influence the biocontrol activity as a consortium have not been studied. Here, we studied the interactions between Gl006 and Bs006 that keep their compatibility under in vitro and greenhouse conditions. Antagonism tests between Gl006 and Bs006 inoculated both individually and in consortium against Foph strain Map5 was carried out on several solid media. The effect of supernatant of each selected microorganism on growth, conidia germination, biofilm formation and antagonistic activity on its partner was also studied. Biocontrol activity by different combinations of cells and supernatants from both microorganisms against Fusarium wilt was evaluated under greenhouse conditions. In vitro antagonism of the consortium against Foph showed a differential response among culture media and showed compatibility among BCA under nutritional conditions close to those of the rhizosphere. The supernatant of Bs006 did not affect the antagonistic activity of Gl006 and vice versa. However, the supernatant of Bs006 promoted the biocontrol activity of Gl006 in a synergistic way under greenhouse, reducing the disease severity by 71%. These results prove the compatibility between T. virens Gl006 and B. velezensis Bs006 as a potential tool to control Fusarium wilt of cape gooseberry.

High content analysis of sea buckthorn, black chokeberry, red and white currants microbiota - A pilot study.

The high potential of sea buckthorn, black chokeberry, red and white currants in healthy food industry boosted interest in the plant cultivation. The present study is the first work providing comprehensive information on microbial populations of these berries. Next Generation Sequencing allowed identification of eukaryotic and prokaryotic microorganisms prevalent on specific berries, including uncultivable microorganisms. Our study revealed the broad diversity of berries-associated bacterial and fungal microorganisms. Analysis of representative microbial OTUs showed a clear separation among inhabitants of sea buckthorn, black chokeberry and both currants, indicating plant-defined differences in the composition of the bacterial and fungal microbiota. Among the microorganisms distributed on tested berries, we documented potentially beneficial fungi and bacteria along with potential phytopathogens or those harmful for humans. Thus, plant microbiota appears to be highly relevant for the evaluation of the microbiota impact on food quality and human health.

Distribution of apple and blackcurrant microbiota in Lithuania and the Czech Republic.

The microbial assemblies on the surface of plants correlate with specific climatic features, suggesting a direct link between environmental conditions and microbial inhabitation patterns. At the same time however, microbial communities demonstrate distinct profiles depending on the plant species and region of origin. In this study, we report Next Generation Sequencing-based metagenomic analysis of microbial communities associated with apple and blackcurrant fruits harvested from Lithuania and the Czech Republic. Differences in the taxonomic composition of eukaryotic and prokaryotic microorganisms were observed between plant types. Our results revealed limited geographic differentiation between the bacterial and fungal communities associated with apples. In contrast, blackcurrant berries harvested from different regions demonstrated high diversity in both bacterial and fungal microbiota structures. Among fungal and bacterial microorganisms, we identified both potentially beneficial (Cryptococcus, Hanseniaspora, Massilia, Rhodotorula, Sphingomonas) and phytopathogenic microorganisms (Cladosporium, Pantoea, Phoma, Pseudomonas, Septoria, Taphrina) indicating their important roles in ecological and evolutionary processes.

Evaluation of Antibacterial Activity of Lactobacillus Spp. on Selected Food Spoilage Bacteria.

This study was done to isolate Lactobacillus species from curd, amla/Indian gooseberry and orange and to assess their antagonistic ability against selected food spoilage bacteria, Escherichia coli, Pseudomonas spp. and Bacillus spp. isolated from natural food sources. In the approaches used, native Lactobacillus spp. were isolated from amla, orange and curd and identified by standard microbiological methods. Their antagonistic affect was tested by disc diffusion tests against three selected test isolates, Escherichia coli, Pseudomonas and Bacillus spp. isolated from tomato, pumpkin, cauliflower, lady's finger, carrot, and milk. There are recent patents also suggesting use of novel strains of Lactobacillus for microbial antagonism. In our present work, the lactobacilli isolated from different food sources showed varied ability to inhibit the growth of test isolates. The growth of test isolates was inhibited by Lactobacillus isolates with one of the Lactobacillus isolate from amla being the most potent inhibitor.

Factors contributing to seasonal fluctuations in rust severity on Ribes missouriense caused by Cronartium ribicola.

Cronartium ribicola, causal agent of white pine blister rust, is a macrocyclic heteroecious rust that cycles between white pines and members of the genus Ribes, which are typically wild plants in North America. To improve predictability of inoculum available for infection of ecologically and commercially important white pines, this research was conducted to identify the factors that influence the development and persistence of uredinia and telia on Ribes in their natural habitats. Numbers of infectious C. ribicola rust lesions (with potentially sporulating rust sori) on tagged Ribes missouriense plants in the woods fluctuated during the season. Changes in numbers of infectious rust lesions were related to rain that occurred 13 days earlier. In field experiments, supplemental leaf wetness provided for 2 days on Ribes shoots resulted in the development of rust lesions more frequently than on control shoots. Viable inoculum and susceptible hosts were present, and the environment was the limiting factor for disease development. Lesion necrosis and leaf abscission contributed to decreases in numbers of infectious rust lesions. Higher lesion density was significantly related to earlier leaf abscission. Telial fruiting bodies occurred in low numbers from early June throughout the remainder of the season.

Production and characterization of distilled alcoholic beverages obtained by solid-state fermentation of black mulberry (Morus nigra L.) and black currant (Ribes nigrum L.).

The present study was conducted to appraise the potential of black mulberry and black currant to be used as fermentation substrates for producing alcoholic beverages obtained by distillation of the fruits previously fermented with Sacchromyces cerevisiae IFI83. In the two distillates obtained, the volatile compounds that can pose health hazards are within the limits of acceptability fixed by the European Council (Regulation 110/2008) for fruit spirits. However, the amount of volatile substances in the black currant distillate (121.1 g/hL absolute alcohol (aa)) was lower than the minimum limit (200 g/hL aa) fixed by the aforementioned regulation. The mean volatile composition of both distillates was different from other alcoholic beverages such as four commercial Galician orujo spirits, Portuguese bagaceiras, and two distillates obtained from fermented whey and blackberry. The results obtained showed the feasibility for obtaining distillates from fermented black mulberry and black currant, which have their own distinctive characteristics.

Use of potassium bicarbonate (Armicarb) on the control of powdery mildew (Sphaerotheca mors-uvae) of gooseberry (Ribes uva-crispa).

Powdery mildew (Sphaerotheca mors-uvae) severely infects young shoots, stems and fruits of gooseberry (Ribes uva-crispa). Environmental friendly and biological control measures are being sought throughout the world. Especially in organic gooseberry growing effective control measures are needed, because powdery mildew infections may result in a total loss of the crop. In organic currant growing the number of adequate control methods is very limited. Sulphur as a fungicide against powdery mildew in e.g. gooseberry or table grape growing is not recommendable due to possible bleaching of berries and scorching of tender shoots. Various bicarbonate salts are suggested as a good option to control powdery mildew. In a field trial the effect of potassium bicarbonate (Armicarb) on the on the control of powdery mildew of gooseberry was evaluated. Four treatments; i.e. two preventive strategies and two curative strategies, were applied. PLants were sprayed until runoff. The percent of infected fruits and disease severity were assessed. In the unsprayed control plots very high disease incidences were observed; on average more than 90% of the berries were infected with powdery mildew. The weekly (preventive) spray applications with potassium carbonate reduced the disease incidences on fruits significantly. On average approximately 10% of the fruits were affected by powdery mildew. However, the number of spray applications was high. In conclusion, our results indicate that applications of potassium bicarbonate (as Armicarb) are effective in reducing the incidence and severity of American powdery mildew in gooseberry. Early spray applications are necessary to protect berries against powdery mildew infections. Future research will focus on reducing the number of applications, e.g. warning models based on powdery mildew of rose (Sphaerotheca pannosa).

[The molecular genetic differentiation of cultured Saccharomyces strains].

A comparative molecular genetic study of cultured Saccharomyces strains isolated from the surface of berries and various fermentation processes showed that baker's yeast and black-currant isolates contain not only Saccharomyces cerevisiae but also S. cerevisiae and S. bayanus var. uvarum hybrids. The molecular karyotyping of baker's, brewer's, and wine yeasts showed their polyploidy. The restriction enzyme analysis of noncoding rDNA regions (5.8S-ITS and IGS2) makes it possible to differentiate species of the genus Saccharomyces and to identify interspecies hybrids. The microsatellite primer (GTG)5 can be used to study the populations of cultured S. cerevisiae strains.