Exploitation of Yeasts with Probiotic Traits for Kefir Production: Effectiveness of the Microbial Consortium

Kefir is a fermented milk made by beneficial lactic acid bacteria and yeasts inoculated as grains or free cultures. In this work, five yeast strains with probiotic aptitudes belonging to Candida zeylanoides, Yarrowia lipolytica, Kluyveromyces lactis, and Debaryomyces hansenii species were assessed in a defined consortium, in co-culture with a commercial strain of Lactobacillus casei, in order to evaluate the yeasts’ fermentation performance during kefir production, using different milks. The concentration of each yeast was modulated to obtain a stable consortium that was not negatively affected by the bacteria. Furthermore, all yeasts remained viable for five weeks at 4 °C, reaching about 8.00 Log CFU in 150 mL of kefir, a volume corresponding to a pot of a commercial product. The yeasts consortium showed a suitable fermentation performance in all milks, conferring peculiar and distinctive analytical and aromatic properties to the kefirs, confirmed by a pleasant taste. Overall, the panel test revealed that the cow’s and sheep’s kefir were more appreciated than the others; this evaluation was supported by a distinctive fermentation by-products’ content that positively influences the final aroma, conferring to the kefir exalted taste and complexity. These results allow us to propose the yeasts consortium as a versatile and promising multistarter candidate able to affect industrial kefir with both recognizable organoleptic properties and probiotic aptitudes.

Applicability of Saccharomyces cerevisiae Strains for the Production of Fruit Wines Using Cocoa Honey Complemented with Cocoa Pulp

Research background. Cocoa honey (CH) and cocoa pulp (CP) are both fruit pulps highly appreciated but, until now, CH is less processed than CP. In this work, it was investigated the applicability of strains of S. cerevisiae to ferment CH complemented with CP, to obtain fruit wines and improve CH commercialization. Experimental approach. The selection of a strain, previously isolated from cachaçaria distilleries in Brazil, took place based on its fermentation performance. The conditions for fermentation with S. cerevisiae L63 were then studied in relation to: volumetric proportion (φCH) of CH (complemented with CP), sucrose addition (γsuc), temperature (T) and inoculum size (No). The best conditions were applied in order to obtain fermentation profiles. Results and conclusions. S. cerevisiae L63 (No=107–108 cell/mL) is capable to ferment φCH of 90 and 80 % (V/V) for 24 or 48 h with γsuc of 50 and 100 g/L at T=28–30 °C resulting in wines with ethanol contents from 8 to 14 % (V/V). Additionally, the φCH=90 % (V/V) wine resulted in the lowest residual sugar concentration (<35 g/L) than the φCH=80 % (V/V) wine (~79 g/L) which could be classified as a sweet wine. In general, S. cerevisiae L63 resulted in a similar fermentation performance than a commercial strain tested, indicating its potential for fruit pulp fermentation. Novelty and scientific contribution. Therefore, S. cerevisiae L63 is capable to ferment CH complemented with CP to produce fruit wines with good commercial potentials that may also benefit small cocoa producers by presenting a product with greater added value.

Wine Saccharomyces Yeasts for Beer Fermentation

Multiple studies in recent years have shown the potential of Saccharomyces wild yeasts to produce craft beers with new flavour profiles and other desirable properties. Yeasts isolated from food (wine, bread, kombucha…) have shown potential promise for application in brewing. The aim of this study is to evaluate the ability of 141 Saccharomyces yeast strains isolated from the Madrilenian agriculture (from grapes, must, wine, vineyard, and cellars) to produce a novel ale beer. Fermentation activity of the strains was compared against the commercial strain Saccharomyces cerevisiae Safale S-04. In addition to the other aspects such as melatonin production, thirty-three volatile compounds belonging to higher alcohols, esters, aldehydes/cetones, acids, lactones and phenolic groups, were analysed by GC for selection of the strains. Ten strains were finally chosen, among which the most relevant was the strain G 520 showing a higher production of esters, higher alcohols and acids compared with S-04. The apparent attenuation for this strain was lower than commercial strain, which translates into more residual sugars. Furthermore, G 520 was more capable of producing significantly higher amounts of melatonin studied by HPLC, as well as showing a higher antioxidant capacity. Consumer study showed that G 520 strain could be used to produce a potential beer that has a place in the current market.

Trichoderma asperellum (NST-009): A Possible Thai Native Antagonistic Fungus for Managing White Root Disease of Rubber Trees (Hevea brasiliensis)

Background: Rigidoporus microporus causes white root disease, which is one of the most harmful diseases in rubber trees in Thailand. The objectives of this study were to determine the efficacy of T. asperellum NST-009 and its antifungal metabolite in inhibiting R. microporus mycelial development and efficacy of T. asperellum NST-009 in controlling white root disease of rubber trees in an open-field house experiment. Methods: Four native strains of T. asperellum from Nakhon Si Thammarat Province and a commercial strain of Thailand were used in this study. This study was conducted at Agricultural Microbial Production and Service Center, Walailak University, Nakhon Si Thammarat, Thailand, during the period 2017-2020. Result: T. asperellum NST-009 significantly inhibited R. microporus mycelial growth by 77.07% in vitro and its antifungal metabolite from the culture filtrate of T. asperellum NST-009 inhibited mycelial growth by 92.31%. T. asperellum NST-009 reduced the disease severity index by 76.38% in the open-field house experiment compared to the inoculated control. Furthermore, T. asperellum NST-009 was found to survive in rhizosphere soil at 4.50 × 105 CFU/g soil and colonized the roots at 100.00%.

Performance Characteristics of Additively Printed Strain Gauges Under Different Conditions of Temperature and High Stress Loads

Applications of printed sensors have increased to industrial, consumer electronics, and medical fields with the advancements in the technology of printing and the adaptability of ink. These sensors are used to monitor a variety of measurements, including temperature, humidity, strain, and sweat, with different systems. This paper studies the performance characteristics of additively printed strain sensors using a nScrypt machine with a direct-write printing technique. The ink used in this study is silver ink which is thermally cured and also has a solderable property. The thermal curing temperature and trace width of the printed silver trace is optimized for better performance in the strain measurements, shear load to failure, and resistivity. Once the printing characteristics of the trace are defined, strain gauges are printed on printed wiring boards (PWB) and are tested at different loading and temperature environments. The sustainability and repeatability of the sensor measurements at high-stress conditions are studied using combined temperature and vibration loads of up to 50 degrees Celsius and 10g acceleration levels. The strain characteristics of the printed strain gauges are studied by comparing them to a commercial strain gauge at a similar position on the test substrate. The repeatability and variation of the strain profile are studied with different conditions of temperature and acceleration conditions at different time instants during vibration. The gauge factor of the printed strain gauge is quantified using a 3-point bending experiment with printed and commercial strain gauges at symmetrical locations of the substrate.

Comparable Expressions of Bacillus species on Different Growth Media

An investigation was carried out using Pikovskaya Broth (PKB), Luria Bertani Broth (LBB), and Peptone Water (PW) to analyse growth expressions of constructed Bacillus subtilis sub sp and compared to a commercial Bacillus subtilis RIK 1285. The aim was to determine the effect of carbon, nitrogen and other elements at different variations on the metabolic activities under different conditions. The results obtained showed growth density of 4.1 g/ml at 70oC and 3.1 g/ml at pH 6.0; 3.3 g/ml at 70oC and 2.8 g/ml at pH 6.0; 3.8 g/ml at 60oC and 2.6 g/ml at pH 7.0 from PKB, LBB and PW respectively. The growth density of the commercial strain recorded 3.8 g/ml at 50oC and 2.8 g/ml at pH 7.0; 3.1 g/ml at 50oC and 2.3 g/ml; 3.0 at 50oC and 2.3 at pH respectively. The investigation showed importance and relevance of gene metabolic upgrade on the utilization of multiple nutrients present from one media to another. Keywords: media formulation, microbial reaction, growth promoters, growth density

Selection of Endophytic Beauveria bassiana as a Dual Biocontrol Agent of Tomato Pathogens and Pests

Endophytic fungi (EF) can enhance both plant growth and defense barriers against pests and pathogens, contributing to the reduction of chemical pesticides and fertilizers use in agriculture. Beauveria bassiana is an entomopathogenic fungus showing endophytism in several crops, often associated with a good capacity to limit the development of pests and disease agents. However, the diversity of the protective efficacy and plant response to different strains can be remarkable and needs to be carefully assessed for the successful and predictable use of these beneficial microorganisms. This study aims to select B. bassiana strains able to colonize tomato plants as endophytes as well as to control two important disease agents, Botrytis cinerea and Alternaria alternata, and the pest aphid, Macrosiphum euphorbiae. Nine wild-type isolates and one commercial strain were screened for endophytism, then further characterized for plant-growth promotion plus inhibition of disease development and pest infestation. Four isolates proved to have a good control activity against the biotic stressors tested, but only Bb716 was also able to promote plant growth. This work provides a simple workflow for the selection of beneficial EF, paving the way towards more effective use of B. bassiana in Integrate Pest Management (IPM) of tomato.

Dose-response relationship of Beauveria bassiana (Balsamo) Vuillemin on Rhipicephalus microplus ticks

Background Isolation and optimization are the primary step in the development of fungal pathogens for biological control agents. In this study, three indigenous strains of Beauveria bassiana (Bb-27, Bb-40 and Bb-41) and one commercial strain (Eco-Bb) were tested for dose/response relationship of the fungus against Rhipicephalus microplus ticks. Results We used R. microplus larvae of 2 weeks of age, and exposed them to four conidial concentrations: 1x103, 3x105, 4x107, 3.2x108 conidia.mL− 1 of each strain. Water was used as a control. Larval mortality was significantly affected by the type of formulation. There was a positive relationship between the concentration of the formulation and mortality of the treated ticks. All the ticks treated with the formulation containing 3.2x108 conidia.mL− 1 resulted in high levels of mortality. Conclusions From this study, it can be concluded that, because of the diversity in the performance of B. bassiana strains, optimization of the formulation for different Isolates of B. bassiana can be achieved through scrutinizing the virulence of the Isolates.

Comparative study of hatchability rate and egg quality between different strains of Japanese Quail (Coturnix japonica)

The objectives of this study were to determine morphology of Japanese quail strains andhatchability rate and egg quality between commercial strain which is Poultry Progress Institute(IKTA) strain and White Texas strains of Japanese Quail (Coturnix japonica) rear in Malaysia. Atotal of 300 quails were randomly picked and the breastbone length, chest girth, body weight,body length, shank length and drum length were measured for the morphology. Then, 270 eggs ofCommercial and White Texas strains were used to test the hatchability rate (n=150) and eggquality (n=120). The ratio of the parents of the quails between male and female of each type ofstrain were 1:3. The cleanliness, shape, weight, and texture of the eggshell were observed,weighed and measured. The eggs were incubated for 17 days (37.6 °C, 65% humidity). The shapeindex, egg weight, egg volume and eggshell surface were weighed and measured for the exteriortrait of eggs. For interior trait, the albumen index, Haugh units, and internal quality units (IQU)were measured. Significant findings were observed in all of the features (P<0.05), except for thewing length in morphology. For hatchability rate, there was a high significant in the percentage ofhatchability of incubated eggs, hatchability of fertile eggs and smoothness texture of the eggshell.In egg quality there was high significant in Haugh unit but low significant internal quality unit.The significant variability might be due from the genetic information that inherited from theparents. The IKTA and White strains were not the same in morphology, hatchability rate andinterior trait of eggs but same exterior trait of eggs. In conclusion, this research is important ingiving information about Japanese quail strain in Malaysia and more genetic study should be donein the future to determine good strain and increase understanding about quail strain.