Yeast Colonies Research Articles

Use of hop extract in the biotechnology of kefir beverage

The shelf life of fermented dairy products is only 3-5 days and is extended by the addition of preservatives to the production process, but the biological value of the kefir beverage is reduced. The purpose of this study was to determine the feasibility of using hop extract in the biotechnology of fermented milk beverage. Three samples of kefir beverage were produced: control (K) – using traditional technology based on dry starter “Kefir VIVO”; experimental (D1) – with the above type of starter in the amount of 0.05% by weight of milk and hop extract in the amount of 5% by weight of milk. The experimental sample (D2) was fermented using hop extract (10% by weight of milk). It was found that when using only hop extract for fermentation of the prototype kefir beverage, the duration of the technological process of its production is the same as when using dry starter and does not exceed 7-8 hours. The number of beneficial viable lactic acid microorganisms (Lactococcus lactis ssp.) in the fermented milk beverage made based on hop extract was 1.0∙107 CFU/cm3 . These microorganisms have probiotic properties, which makes it possible to classify beverages enriched with hop extract as functional foods. In the experimental samples made using hop extract, yeast colonies were found in the amount of 3∙107 and 8∙107 CFU/cm3 , respectively. During the experimental storage period, the pH of all product samples was (4.71-4.46). Therewith, the acidity of the sample (D2) increased more slowly. Its organoleptic characteristics were improving. The shelf life has been extended to 10-15 days. The results of the study showed that milk can be fermented with hop extract, resulting in a new functional type of kefir beverage with high organoleptic characteristics, viability of beneficial microflora (lactic acid bacteria and yeast) and extended shelf life

Yeast species in the respiratory samples of COVID-19 patients; molecular tracking of Candida auris.

Although the existence of Candida species in the respiratory tract is often considered commensal, it is crucial to recognize the significance of Candida colonization in immunocompromised or COVID-19 patients. The emergence of Candida auris as an emerging pathogen further emphasizes the importance of monitoring yeast infection/colonization, particularly in COVID-19 patients. In this study, respiratory samples mainly from COVID-19 patients, primarily those suspected of having a fungal infection, were cultured on Sabouraud dextrose agar plates and the yeast colonies were identified using a two-step multiplex PCR method. The samples suspected of C. auris underwent specific nested PCR followed by sequence analysis. A total of 199 respiratory samples were collected from 73 women and 126 men, ranging in age from 1.6 to 88 years. Among the patients, 141 had COVID-19, 32 had cancer, 5 were hospitalized in ICU, 2 had chronic obstructive pulmonary disease)COPD(, and others were patients with combination diseases. From these samples, a total of 334 yeast strains were identified. C. albicans (n=132, 39.52%) was the most common species, followed by C. tropicalis (n=67, 20%), C. glabrata (n=56, 16.76%), C. krusei (n=18, 5.4%), C. parapsilosis (n=17, 5.08%), Saccharomyces cerevisiae (n=10, 3%), C. kefyr (n=9, 2.6%), C. dubliniensis (n=7, 2.1%), C. lusitaniae (n=5, 1.5%), C. auris (n=3, 0.9%), C. guilliermondii (n=2, 0.6%), C. rugosa (n=1, 0.3%), C. intermedia (n=1, 0.3%), and Trichosporon spp. (n=1, 0.3%). C. auris was detected in a patient in ICU and two COVID-19 patients. While its presence was confirmed through sequence analysis, our extensive efforts to isolate C. auris were unsuccessful. While C. albicans colonization remains prevalent, our study found no evidence of Candida lung infection. Since the role of Candida colonization in airway secretions remains ambiguous due to limited research, further studies are imperative to shed light on this matter.

Prvi opis proizvodnje piva pomoću morskih kvasaca

Most of the yeast species we encounter daily are terrestrial, but they are also found in the marine environment. Marine yeasts occur in estuaries, coastal and open marine waters, sediments, and as epi- and endobionts of various marine organisms. This study focuses on the fermentation capabilities of marine yeasts isolated from the central Adriatic Sea for use in the brewing process. Sampling was performed at a sea temperature of 12°C to avoid collecting yeasts introduced into the marine environment by human activities. Four nutrient media designed for yeast isolation and growth were used to isolate yeasts from the marine samples: Yeast Malt Agar (YM), Yeast Malt Agar with antibiotics, acidified Yeast Malt Agar, and Sabouraud Dextrose Agar. Sixteen yeast colonies were successfully isolated, and only three were positive in the fermentationtest and were further determined to species level. Of the three species identified as capable of fermentation, Candida famata completely fermented the wort and produced a beer. Candida pelliculosa fermented slowly over an extended period and did not produce a usable beer, while Candida sake did not ferment the wort at all. To our knowledge, this is the first time that marine yeast isolates have been used experimentally for beer fermentation, indicating potential for use as nonconventionalyeasts in brewing and beer production. Further investigations should include professional standard fermentation, aroma and genetic studies.

Design and assembly of the 117-kb Phaeodactylum tricornutum chloroplast genome.

There is growing impetus to expand the repertoire of chassis available to synthetic biologists. Chloroplast genomes present an interesting alternative for engineering photosynthetic eukaryotes; however, development of the chloroplast as a synthetic biology chassis has been limited by a lack of efficient techniques for whole-genome cloning and engineering. Here, we demonstrate two approaches for cloning the 117-kb Phaeodactylum tricornutum chloroplast genome that have 90% to 100% efficiency when screening as few as 10 yeast (Saccharomyces cerevisiae) colonies following yeast assembly. The first method reconstitutes the genome from PCR-amplified fragments, whereas the second method involves precloning these fragments into individual plasmids from which they can later be released. In both cases, overlapping fragments of the chloroplast genome and a cloning vector are homologously recombined into a singular contig through yeast assembly. The cloned chloroplast genome can be stably maintained and propagated within Escherichia coli, which provides an exciting opportunity for engineering a delivery mechanism for bringing DNA directly to the algal chloroplast. Also, one of the cloned genomes was designed to contain a single SapI site within the yeast URA3 (coding for orotidine-5'-phosphate decarboxylase) open-reading frame, which can be used to linearize the genome and integrate designer cassettes via golden-gate cloning or further iterations of yeast assembly. The methods presented here could be extrapolated to other species-particularly those with a similar chloroplast genome size and architecture (e.g. Thalassiosira pseudonana).

Protein-Protein Interaction via Two-Hybrid Assay in Yeast.

The yeast two-hybrid assay enables detecting interactions between proteins, which makes this tool of particular interest for plant-virus interaction studies. Basically, the reporter gene expression (HIS3) is activated by the binding of a transcription factor GAL4, which, like eukaryotic transcription factors, is modular in nature and consists of two structurally independent domains: DNA-binding (DB) and activation (AD) domains. The two proteins under investigation are expressed separately, one fused to the BD domain and the other to the AD domain. In the yeast strain AH109, activation of the reporter gene occurs only in cells that contain interacting proteins, reconstituting the transcription factor GAL4 which then binds to the responsive promoter and results in yeast colony growth.

Antifungal Properties of Ozone Treatment against P. citrinum and R. stolonifera in Fresh-Peeled Garlic

Garlic is susceptible to decay and presents a potential vehicle for foodborne disease transmission. Ozone treatment has proven to be an effective and innoxious method to provide bacterial resistance in this globally popular pungent vegetable. This study was conducted to evaluate the effects of different ozone treatments (differing in terms of concentration, treatment time and temperature) against Penicillium citrinum and Rhizopus stolonifer in spoiled fresh-peeled garlic. The results have shown that the most inhibitory conditions for in vitro treatments were achieved with an ozone concentration, treatment time and temperature of 6 ppm, for 20 min at 20 °C, respectively, on the P. citrinum and 8 ppm, for 20 min at 25 °C, respectively, on the R. stolonifer. The optimum in vivo ozone treatment conditions for fresh-peeled garlic inoculated with the same two kinds of spoilage molds remained the same for both, consisting of an ozone concentration of 6 ppm, a time of 15 min and a temperature of 20 °C. Following these ozone treatments, the total number of colonies of yeast and mold, as well as the incidence, lesion diameter and depth of spoilage in the fresh-peeled garlic was significantly reduced during storage, with improved bactericidal inhibition effects. In conclusion, this study showed that ozone treatment effectively inhibits the growth of spoilage molds, destroys cell structures, and affects the metabolic and physiological processes of P. citrinum and R. stolonifer. Thus, it provides a protective shield and extends the shelf life of fresh-peeled garlic.

The Effect of Curcumin and Cornstarch Biopolymers on the Shelf Life of Fresh Cheese: Physicomechanical and Antimicrobial Properties

AbstractNatural polymers are used more frequently in packaging as alternatives to synthetic plastics. Cornstarch is one of the cheapest carbohydrate biopolymers that form films with suitable properties and appearance but considerably larger hydrophilicity and low mechanical characteristics compared to synthetic films. Incorporating curcumin into cornstarch films improves mechanical and antimicrobial properties and curcumin release into aqueous solutions of the films. The results show that the introduction of curcumin decreases the water solubility of the edible films from 3.58% to 1.49% and the moisture absorption from 2.87% to 1.94% (p < 0.05) and increases the length of films from 40% to 80% without changing their thickness. Examination of color properties shows that the increased curcumin concentration leads to a decrease in transparency and an increase in the redness and yellowness indices. These properties change from 72.2, 3.5, and 5.1 to 39.2, 21, and 13.7, respectively. The number of mold and yeast colonies in the cheese sample decreases during the storage period of 5 days. Generally, the findings indicate that the bioactive film of corn starch and curcumin (0.5%) can be used as a suitable coating for food products.

In vitro evaluation of probiotic properties of yeasts and lactic acid bacteria isolated from ersho samples collected from different parts of Ethiopia

ABSTRACT Ersho is an undefined starter culture used for Ethiopian injera production, and it is a good source of yeasts and lactic acid bacteria (LAB). However, few researchers have been done on the characterization of yeasts and LAB from ersho samples as a source of probiotics. The objective of the current work was to isolate and screen yeasts and LAB from ersho samples and in vitro characterization of their probiotic properties. An experimental research design was used. A total of 55 ersho samples were collected. Based on the ersho samples, 220 yeast colonies and 220 LAB colonies were isolated and purified. For the probiotic characterization, three yeasts (4A, 14D, 54A) and three LAB (1A, 13E, and 55A) were chosen. The isolates 4A, 14D, 54A, 1A, 13E, and 55A were identified as Saccharomyces cerevisiae KRSAN1, Saccharomyces cerevisiae JYC2577, Kazachstania humilis, Enterococcus lactis, Lactobacillus paracasei, and Lactobacillus species, respectively. All the isolates showed positive probiotic characteristics. They had very good acid resistance (percentage survival > 80%), high bile salt resistance (percentage survival > 140%), high cell surface hydrophobicity (>40%), high levels of auto-aggregation (>40%), variable co-aggregation with pathogens (ranged between 42% and 72%), variable antimicrobial activity (clear halo zone ranged from 4.0 to 31 mm), and variable antibiotic resistance responses. The results indicated that the ersho samples can be used as yeast and LAB sources for developing food and probiotic starter cultures.

A mathematical model for nutrient-limited uniaxial growth of a compressible tissue

We consider the uniaxial growth of a tissue or colony of cells, where a nutrient (or some other chemical) required for cell proliferation is supplied at one end, and is consumed by the cells. An example would be the growth of a cylindrical yeast colony in the experiments described by Vulin et al. (2014). We develop a reaction–diffusion model of this scenario which couples nutrient concentration and cell density on a growing domain. A novel element of our model is that the tissue is assumed to be compressible. We define replicative regions, where cells have sufficient nutrient to proliferate, and quiescent regions, where the nutrient level is insufficient for this to occur. We also define pathlines, which allow us to track individual cell paths within the tissue. We begin our investigation of the model by considering an incompressible tissue where cell density is constant before exploring the solution space of the full compressible model. In a large part of the parameter space, the incompressible and compressible models give qualitatively similar results for both the nutrient concentration and cell pathlines, with the key distinction being the variation in density in the compressible case. In particular, the replicative region is located at the base of the tissue, where nutrient is supplied, and nutrient concentration decreases monotonically with distance from the nutrient source. However, for a highly-compressible tissue with small nutrient consumption rate, we observe a counter-intuitive scenario where the nutrient concentration is not necessarily monotonically decreasing, and there can be two replicative regions. For parameter values given in the paper by Vulin et al. (2014), the incompressible model slightly overestimates the colony length compared to experimental observations; this suggests the colony may be somewhat compressible. Both incompressible and compressible models predict that, for these parameter values, cell proliferation is ultimately confined to a small region close to the colony base.

Multi-omics characterization of the microbial populations and chemical space composition of a water kefir fermentation.

In recent years, the popularity of fermented foods has strongly increased based on their proven health benefits and the adoption of new trends among consumers. One of these health-promoting products is water kefir, which is a fermented sugary beverage based on kefir grains (symbiotic colonies of yeast, lactic acid and acetic acid bacteria). According to previous knowledge and the uniqueness of each water kefir fermentation, the following project aimed to explore the microbial and chemical composition of a water kefir fermentation and its microbial consortium, through the integration of culture-dependent methods, compositional metagenomics, and untargeted metabolomics. These methods were applied in two types of samples: fermentation grains (inoculum) and fermentation samples collected at different time points. A strains culture collection of ∼90 strains was established by means of culture-dependent methods, mainly consisting of individuals of Pichia membranifaciens, Acetobacter orientalis, Lentilactobacillus hilgardii, Lacticaseibacillus paracasei, Acetobacter pomorum, Lentilactobacillus buchneri, Pichia kudriavzevii, Acetobacter pasteurianus, Schleiferilactobacillus harbinensis, and Kazachstania exigua, which can be further studied for their use in synthetic consortia formulation. In addition, metabarcoding of each fermentation time was done by 16S and ITS sequencing for bacteria and yeast, respectively. The results show strong population shifts of the microbial community during the fermentation time course, with an enrichment of microbial groups after 72h of fermentation. Metataxonomics results revealed Lactobacillus and Acetobacter as the dominant genera for lactic acid and acetic acid bacteria, whereas, for yeast, P. membranifaciens was the dominant species. In addition, correlation and systematic analyses of microbial growth patterns and metabolite richness allowed the recognition of metabolic enrichment points between 72 and 96h and correlation between microbial groups and metabolite abundance (e.g., Bile acid conjugates and Acetobacter tropicalis). Metabolomic analysis also evidenced the production of bioactive compounds in this fermented matrix, which have been associated with biological activities, including antimicrobial and antioxidant. Interestingly, the chemical family of Isoschaftosides (C-glycosyl flavonoids) was also found, representing an important finding since this compound, with hepatoprotective and anti-inflammatory activity, had not been previously reported in this matrix. We conclude that the integration of microbial biodiversity, cultured species, and chemical data enables the identification of relevant microbial population patterns and the detection of specific points of enrichment during the fermentation process of a food matrix, which enables the future design of synthetic microbial consortia, which can be used as targeted probiotics for digestive and metabolic health.

Evaluation of Usefulness of Yeast-Based Biological Phantom and Preliminary Study for Verification of Hypoxic Effect of Flash Radiotherapy

As a basic hypothesis for the effectiveness of flash radiation therapy, the effect of preserving normal tissue during flash radiation is due to the instantaneous chemical depletion of oxygen. A yeast-based biological phantom was created to verify the hypoxic effect of flash radiation therapy. A study to upgrade the previously developed X-Band LINAC to a flash irradiation mode is in progress, and a preceding study is conducted to evaluate the usefulness of a yeast-based biological phantom manufactured by analyzing the change in oxygen by irradiating a high dose in a general radiation therapy device. Freeze-dried yeast sample (Saccharomyces cerevisiae, S288C) is activated and sub-cultured. For mass production of yeast samples, yeast culture medium is prepared by adding yeast colonies to the ypd medium. This study was conducted to verify the hypoxic effect among the biological mechanisms that occur during flash radiation therapy at the basic stage, and the oxygen concentration change during general radiation irradiation was measured in real time using a DO (Dissolved oxygen) meter and fiber optic sensor designed to do that. To prevent scatter, which is a concern during flash irradiation, the fiber form was used, and precise experiments are possible as a non-invasive oxygen concentration measurement method. Based on 10MV of general radiation therapy device, high-dose radiation of 500-10,000 cGy is irradiated to measure real-time oxygen concentration change. As a result of irradiation with high-dose (500-10,000 cGy) radiation of general LINAC, it was confirmed that the oxygen concentration of the yeast culture medium decreased by 5.7-63.2%, and the usefulness of the biological phantom fabricated based on the yeast culture medium was evaluated. Prior to the analysis of oxygen concentration change in yeast cells during X-Band LINAC flash irradiation, a preliminary study was conducted at a high dose in a general LINAC to obtain a significant result of oxygen concentration change and confirm the usefulness of the yeast-based biological phantom. Prior research was conducted and verified as a general irradiation experiment using a yeast-based biological phantom manufactured based on a DO meter and a fiber optic oxygen sensor. After irradiation with high-dose radiation, the oxygen concentration of the yeast culture medium was measured 5 times, and it was confirmed that there was a change in oxygen concentration of 5.7-63.2%, verifying the usefulness and stability of the biological phantom. The usefulness of the yeast-based biological phantom for high doses was confirmed, and it is expected that the usefulness of the biological phantom for flash radiation can be verified by additionally measuring the change in oxygen concentration of the biological phantom according to the high dose rate in the future.

Indoor Air Contamination by Yeasts in Healthcare Facilities: Risks of Invasive Fungal Infection

Introduction-Aims: Fungi are ubiquitous microorganisms that are easily dispersed through the air. In healthcare environments, indoor air can favor the spread of healthcare-associated fungal infections, compromising mainly immunocompromised hospitalized individuals. Therefore, this study aimed to evaluate indoor air contamination in healthcare environments, investigating mainly the presence of potentially pathogenic yeasts. Method: Indoor air samples were collected from 12 healthcare environments (hospital and medical clinics). After the growth, isolation, and purification of the yeast colonies, the isolates were identified by polymerase chain reaction using species-specific primers for yeasts of the genus Candida and sequencing of D1/D2 domains of the large ribosomal subunit (LSU rRNA). Results and interpretation: Fourteen yeast species were identified, including emerging pathogens. Species of clinical importance such as Candida parapsilosis, Candida glabrata, and Rhodotorula mucilaginosa were present. C. parapsilosis was the most prevalent species, followed by Rhodotorula mucilaginosa. In addition, we report the first occurrence of Candida orthopsilosis, Trichosporon mucoides, Fereydounia khargensis, and Hortaea werneckii in indoor air samples collected in healthcare environments. The present study shows that potentially fungal pathogens were present in air samples from healthcare environments, proving the role of indoor air in spreading infections. Therefore, monitoring air quality in healthcare environments is a fundamental approach to developing infection control measures, especially those related to invasive fungal infections.

Genetic diversity of non-Saccharomyces yeasts associated with spontaneous fermentation of Cabernet Sauvignon wines from Ningxia, China.

The organoleptic profile and quality of wine are affected by the presence of different non-Saccharomyces species and strains. Therefore, the identification and characterization of non-Saccharomyces yeasts are the first step to understand their function, and to develop a better strain selection program for winemaking. This study investigated the biodiversity of non-Saccharomyces yeasts associated with spontaneous fermentation of Cabernet Sauvignon wines from five sub-regions (Shi Zuishan, Yinchuan, Yu Quanying, Qing Tongxia and Hong Sibu) in Ningxia, China. Yeast species were identified by sequencing the 26S rRNA D1/D2 region, and strains at the subspecies level were discriminated using tandem repeat-tRNA (TRtRNA) PCR analysis. A total of 524 yeast colonies were isolated, and 19 non-Saccharomyces yeast species belonging to 10 genera were identified, including Aureobasidium pullulans, Cryptococcus albidus, Cryptococcus sp., C. flavescens, C. terrestris, C. magnus, Cystofilobasidium ferigula, Candida zemplinina, Filobasidium magnum, Filobasidium sp., F. elegans, Hanseniaspora uvarum, Metschnikowia pimensis, M. pulcherrima, Naganishia albida, Pichia kluyveri, P. kudriavzevii, Rhodotorula glutinis and R. graminis. Hanseniaspora uvarum, C. zemplinina, and M. pulcherrima were the three most dominated species, while other non-Saccharomyces species were only present in the early stage of spontaneous fermentations at different levels. Further, for the yeast discrimination at strain level, 34 profiles were obtained by amplification with primer pairs TtRNASC/5CAG, while 40 profiles were obtained with primer pairs TtRNASC/ISSR-MB. This study explored the diversity of non-Saccharomyces species in Ningxia, China, and made an important contribution of genetic resources for further strain development.

Isolation and identification of native yeasts from the spontaneous fermentation of grape musts.

Recently, there has been growing interest in the characterization of native yeasts for their use in production of wines with regional characteristics. This study aimed to investigate Saccharomyces and non-Saccharomyces yeasts present in the spontaneous fermentation of Tannat and Marselan grape musts collected from Concordia (Entre Ríos, Argentina) over 2019, 2020, and 2021 vintages. The evolution of these fermentative processes was carried out by measuring total soluble solids, total acidity, volatile acidity, pH, ethanol concentration, and total carbon content. Isolated Saccharomyces and non-Saccharomyces yeasts were identified based on colony morphology in WL medium, 5.8S-ITS-RFLP analysis, and 26S rDNA D1/D2 gene sequencing. Two hundred and ten yeast colonies were isolated and identified as Pichia kudriavzevii, Saccharomyces cerevisiae, Hanseniaspora uvarum, Metschnikowia pulcherrima, Candida albicans, Candida parapsilosis, Pichia occidentalis, Pichia bruneiensis, Hanseniaspora opuntiae, Issatchenkia terricola, and Hanseniaspora vineae. P. kudriavzevii isolated from all vintages was associated with the spontaneous fermentation of grape musts from the Concordia region.

Development and characterization of sauces formulation based on tomato and garlic powders

Background: Consumers have increasingly high demands in terms of taste, color and texture; they expect foods to be safe, healthy and nutritious, more appealing in color, texture and taste, and ready-to-use products such as sauces. Aim: The aim of this study was to formulate sauces with tomato (TP) and garlic (GP) powders resulted from conventional and microwave dryings. Material and Methods: TP was used at 0, 5, 10 and 15% in the formulation of tomato sauce and GP at 0, 5, and 20% in the formulation of garlic sauce. For studying the effects of these powders on quality of sauces, some properties such as pH, Brix, apparent viscosity, mesophilic aerobic total flora (MATF), total coliforms,mold and yeast colony count and sensory evaluation were determined. Results: The results showed that the increase in the powders proportions increased pH from 5.32 to 5.72 for garlic sauces but decreased it from 5.42 to 5.04 for tomato sauces. However, the Brix values increased from 12.8 (5% tomato sauce) to 19.6% (15% tomato sauce), and from 15.5 (5% garlic sauce) to 18.8% (20% garlic sauce).On the other hand, it caused decrease in apparent viscosity from 7 to 3.5 cm for tomato sauces and from 5to 2.5 cm for garlic sauces. Similarly, MATF, mold and yeast colony count in sauce samples were diminished. Conclusion: The use of TP at 5% (estimated by 60% of the experts) is recommended for the formulation of the tomato sauce whereas for the garlic sauces, the two formulations used were equally appreciated by 100% of the experts. Keywords: Tomato sauce, garlic sauce, physicochemical analysis, microbiological analysis, sensory analysis.

Metabolites Alteration and Antioxidant Activity of Gracilaria verrucosa After Fermentation Using Aureobasidium melanogenum MTGK.31

Gracilaria verrucosa is a red seaweed that has been widely utilized in the food andpharmaceutical industries due to its biological properties. The utilization of biologicalagents in obtaining certain bioactive compounds would confront unavoidable issues,particularly its bioactive sustainability. Hence, microbial fermentation has been reported as a practical approach to maintaining bioactive production and boosting its properties. Our study aimed to evaluate the potential of marine yeast Aureobasidium melanogenum MTGK.31 as a fermenting agent for G. verrucosa and characterize the seaweed metabolite profile and antioxidant activity after fermentation. The seaweed was fermented using A. melanogenum MTGK.31 in a medium consisting of yeast extract, peptone, and glucose. The fermentation was done for 24, 48, and 72 hours. Total plate count and pH were measured after each fermentation period. The primary and secondary metabolites of G. verrucosa in each fermentation were observed. Antioxidant assay using the 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH) method was conducted, followed by total phenolic content using the Folin-Ciocalteu method. It was highlighted that yeast colony increased during the fermentation, while the pH level was decreasing. We found that the fermentation not only boosted some elements in primary metabolites, but also increased G. verrucosa bioactive groups. After 72 hours of fermentation, the G. verrucosa percent radical scavenging activity (%RSA) increased more than two times compared to the fresh G. verrucosa with a %RSA value of 16.09±6.57. Nevertheless, the highest total phenolic content of 5.62±0.00028 mg GAE/g extract was shown by G. verrucosa after 48 hours of fermentation.

Metabolites Alteration and Antioxidant Activity of Gracilaria verrucosa After Fermentation Using Aureobasidium melanogenum MTGK.31

Gracilaria verrucosa is a red seaweed that has been widely utilized in the food and pharmaceutical industries due to its biological properties. The utilization of biological agents in obtaining certain bioactive compounds would confront unavoidable issues, particularly its bioactive sustainability. Hence, microbial fermentation has been reported as a practical approach to maintaining bioactive production and boosting its properties. Our study aimed to evaluate the potential of marine yeast Aureobasidium melanogenum MTGK.31 as a fermenting agent for G. verrucosa and characterize the seaweed metabolite profile and antioxidant activity after fermentation. The seaweed was fermented using A. melanogenum MTGK.31 in a medium consisting of yeast extract, peptone, and glucose. The fermentation was done for 24, 48, and 72 hours. Total plate count and pH were measured after each fermentation period. The primary and secondary metabolites of G. verrucosa in each fermentation were observed. Antioxidant assay using the 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH) method was conducted, followed by total phenolic content using the Folin-Ciocalteu method. It was highlighted that yeast colony increased during the fermentation, while the pH level was decreasing. We found that the fermentation not only boosted some elements in primary metabolites, but also increased G. verrucosa bioactive groups. After 72 hours of fermentation, the G. verrucosa percent radical scavenging activity (%RSA) increased more than two times compared to the fresh G. verrucosa with a %RSA value of 16.09±6.57. Nevertheless, the highest total phenolic content of 5.62±0.00028 mg GAE/g extract was shown by G. verrucosa after 48 hours of fermentation.

The hypothermic nature of fungi

Fungi play essential roles in global health, ecology, and economy, but their thermal biology is relatively unexplored. Mushrooms, the fruiting body of mycelium, were previously noticed to be colder than surrounding air through evaporative cooling. Here, we confirm those observations using infrared thermography and report that this hypothermic state is also observed in mold and yeast colonies. The relatively colder temperature of yeasts and molds is also mediated via evaporative cooling and associated with the accumulation of condensed water droplets on plate lids above colonies. The colonies appear coldest at their center and the surrounding agar appears warmest near the colony edges. The analysis of cultivated Pleurotus ostreatus mushrooms revealed that the hypothermic feature of mushrooms can be observed throughout the whole fruiting process and at the level of mycelium. The mushroom's hymenium was coldest, and different areas of the mushroom appear to dissipate heat differently. We also constructed a mushroom-based air-cooling prototype system capable of passively reducing the temperature of a semiclosed compartment by approximately 10°C in 25 min. These findings suggest that the fungal kingdom is characteristically cold. Since fungi make up approximately 2% of Earth's biomass, their evapotranspiration may contribute to cooler temperatures in local environments.

Effects of brewer's spent yeast inclusion level and ensiling duration on fermentative, fungal load dynamics, and nutritional characteristics of brewer's spent yeast-based silage

ObjectiveThis study was conducted to evaluate the effect of brewer's spent yeast (BSY) inclusion level and ensiling duration (ED) on fermentative, fungal load dynamics, and nutritional characteristics of brewer's spent-yeast based silage. Materials and methodsTo prepare the silages materials, 4 BSY inclusion levels (0, 10, 20, and 30%) to replace BSG and 3 ED (2,4 and 6 weeks) were arranged in 4 × 3 factorial combination using a completely randomized design (CRD) in 5 replications. The ratio of brewery spent grain (BSG) to wheat bran (WB) used majorly as protein and energy sources, respectively was 30:69 with a 1% salt addition. Parameters measured include observation for surface spoilage, yeast and mold colony count, silage temperature, pH, total dry matter loss (TDML), major proximate, detergent fractions and permanganate lignin, in-vitro organic matter digestibility (IVOMD) and estimated metabolizable energy (EME) values. ResultsThe study revealed that at any BSY inclusion level and ED, extensive mold growths and discolorations were not observed. However, slightly higher values of 6.5, 5.7, and 12.2 colonies forming unit (CFU)/g DM yeast, mold, and total fungal counts (TFC), respectively were recorded only at the 6 weeks of the fermentation period with 30% BSY inclusion level. Brewer's spent yeast inclusion level and ED had a significant (P < 0.05) effect on silage temperature (mean = 18.05 °C) and pH (mean = 4.16). Among proximate and detergent values, crude protein (mean CP g/kg DM = 204.5), neutral detergent fiber (mean NDF g/kg DM = 552.9), and acid detergent fiber (mean ADF g/kg DM = 115.9) responded significantly (P < 0.05) to both BSY inclusion levels and ED. ConclusionAmong nutritional quality, CP, IVOMD, and EME of silage samples were subjected to substantial improvements when silage masses were prepared from 20% BSY inclusion levels and when the same silage materials were allowed to ferment for four weeks. In addition, the lab-based experiment should be supported with additional silage quality parameters like volatile fatty acid content of the silage materials and supplementation of ruminant livestock under both on-station and on-farm conditions using either a pilot and/or target animals.

대체 감미료를 활용한 저칼로리 콤부차 제조 및 특성

Kombucha is produced by the action of sugar and fermentative symbiotic colonies of bacteria and yeast (SCOBY) in black and green tea infusions. The main active substances in kombucha are polyphenol compounds (epigallocatechin gallate, epicatechin gallate, gallocatechin gallate, epicatechin, epigallocatechin, gallocatechin, and catechin), vitamins (B1, B2, B6, B12, and C), and organic acids (D-gluconic acid, and glucuronic acid). Several studies have reported that the main health benefits of kombucha include its energizing and detoxifying properties, in addition to anticancer and anti-aging effects. Sugar is a very important component necessary for glucose fermentation. However, this may result in increased consumption of calories depending on the sugar content. Therefore, this study investigated the quality characteristics of commercial kombucha and manufactured low-calorie kombucha (MLK) using alternative sweeteners (non-digestible maltodextrin, enzymatically modified stevia, or sucralose) and different levels of sugarcane content. The total soluble solids content, pH, color, organic acids, catechins, and caffeine content in kombucha during fermentation were then measured. The results showed that there was no significant difference in color. However, the pH of the MLK decreased from 5.4 to 2.81 during fermentation. Interestingly, the highest D-gluconic acid content was observed when 5% (w/v) sugarcane was added to the MLK and fermented for 16 days. The catechin contents did not change during fermentation. The caffeine content decreased from 2.00 ± 0.01 mg/100 mL to 0.94 ± 0.00 mg/100 mL. In conclusion, this study developed low-calorie kombucha using alternative sweeteners, which suggests a new trend in the manufacture of kombucha.