-
Applied Bionics and Biomechanics 2022Detection of food spoilage with simple and fast methods is an important issue in food security and safety. The present study is mainly aimed at identifying and...
Detection of food spoilage with simple and fast methods is an important issue in food security and safety. The present study is mainly aimed at identifying and quantifying four yeast species in white fresh soft cheese using an electronic nose (EN). The yeast species , , , and were used. Six concentrations of each yeast species (100, 200, 400, 600, 800, and 1000 cells/g cheese) were inoculated in 100 g of fresh soft cheese and incubated for 48 h at 25°C. The EN was used to identify and quantify different yeast species in cheese samples. It was found that EN was able to discriminate between four yeast species using principal component analysis (PCA). Moreover, EN was able to quantify in good precision three (, , and ) of the four tested yeasts presented in cheese samples using partial least squares (PLS) models. It seems that EN is a reliable tool that can be used as a fast technique to identify and quantify cheese spoilage in the cheese industry.
PubMed: 35082918
DOI: 10.1155/2022/8472661 -
Brazilian Journal of Microbiology :... Dec 2021Yeast isolates from flowers and fruits from a Brazilian forest were studied. The yeasts were identified at species and strain level by PCR-RFLP and PCR-RAPD,...
Yeast isolates from flowers and fruits from a Brazilian forest were studied. The yeasts were identified at species and strain level by PCR-RFLP and PCR-RAPD, respectively. The 46 isolated yeasts were classified into 11 different species belonging to the genera Candida, Diutina, Hanseniaspora, Meyerozyma, Pichia, Rhodotorula, and Torulaspora. A total of 20 different strains were found. In order to ascertain the probiotic potential, the resistance to gastrointestinal conditions, autoaggregation, and hydrophobicity assays were studied, along with the capacity to form biofilm. The results indicate that, although most of the strains presented better results than Saccharomyces boulardii (the only strain recognized as a probiotic yeast), four strains were the most promising, namely, Rhodotorula mucilaginosa 32, Meyerozyma caribbica 35, and Diutina rugosa 12 and 45, according to the Duncan test. Several biotechnological properties were evaluated. D. rugosa inhibited Dekkera bruxellensis. The assimilation or fermentation of seven sugars was tested, and only five of the yeasts did not show a capacity to assimilate any of the sugars under aerobic conditions. However, all strains were able to ferment at least one of the sugars under anaerobic conditions. As far as enzyme production is concerned, positive results were only found for the enzymes' amylase, pectinase, and protease. D. rugosa 42 and Hanseniaspora opuntiae 18, followed of Pichia kluyveri 26, showed high values for the production of melatonin. In conclusion, the results of this study show that several non-Saccharomyces present probiotic characteristics, and these have good potential for industrial applications in the food or biotechnology industries.
Topics: Biotechnology; Ecosystem; Fermentation; Fruit; Probiotics; Random Amplified Polymorphic DNA Technique; Sugars; Yeasts
PubMed: 34595728
DOI: 10.1007/s42770-021-00541-z -
World Journal of Microbiology &... Feb 2021This study aimed to assess the microbial diversity in Coffea canephora grown in four different environments of Espirito Santo state, Brazil. Coffee cherries of two...
This study aimed to assess the microbial diversity in Coffea canephora grown in four different environments of Espirito Santo state, Brazil. Coffee cherries of two different altitudes (300 and 600 m) and two terrain aspects (Southeast-facing and Northwest-facing slopes) were processed by the dry method. Samples were collected during the drying/fermentation process. Microorganisms were counted, isolated, and identified by MALDI-TOF, followed by sequencing of the ribosomal region. Sugars and organic acids were quantified by HPLC and volatile compounds of the roasted coffees were evaluated by GC-MS. Bacteria population presented a significant number of isolates as well as higher counts during the drying/fermentation process with respect to the population of yeasts. The principal genera of microorganisms found were Bacillus, Pichia, Candida, and Meyerozyma. Meyerozyma guilliermondii was the most frequent yeast in all environments. On the other hand, Pichia kluyveri was found only in coffee cherries from the 600 m altitude. The highest concentration of acetic and succinic acids observed was 6.06 mg/g and 0.84 mg/g, respectively. Sucrose concentrations ranged from 0.68 to 5.30 mg/g, fructose from 1.30 to 4.60 mg/g, and glucose from 0.24 to 1.25 mg/g. Thirty-six volatile compounds, belonging to the groups of pyrazines, alcohols, aldehydes, ketones, and furans were identified in roasted coffee, with differences between altitude and terrain aspects. Information about microbial diversity is crucial to better understand the coffee quality and distinct characteristics of coffee produced in different environments.
Topics: Alcohols; Bacteria; Brazil; Coffea; Coffee; Desiccation; Fermentation; Food Handling; Fungi; Gas Chromatography-Mass Spectrometry
PubMed: 33594606
DOI: 10.1007/s11274-021-03017-2 -
Food Microbiology Sep 2021This work aimed to evaluate Coffea canephora's microbiological, chemical, and sensory characteristics at 300 and 600 m elevation plantations processed by the natural...
This work aimed to evaluate Coffea canephora's microbiological, chemical, and sensory characteristics at 300 and 600 m elevation plantations processed by the natural method inoculated with yeasts. The coffee was spread on suspended terraces and sprayed with approximately 10 cfu/mL of Meyerozyma caribbica CCMA 1738 or Pichia kluyveri CCMA 1743, separately. Cherries containing bark and parchment were collected during fermentation for microbial groups counting, qPCR, quantification of organic acids, and sugars (HPLC). Volatile compounds (GC-MS) and sensory analyses, cupping test with expert coffee tasters and triangular test with consumers, were performed on roasted coffee beans. The inoculated yeasts persisted during the entire fermentation process. M. caribbica reduced the filamentous fungal population by 63% and 90% in the 300- and 600-m coffees, respectively. The 300-m coffee fruits showed higher concentrations of organic acids in all fermentation times when compared to the 600-m reaching out to 8 times more. Twenty-four volatile compounds were identified in the roasted coffee beans, with the predominance of pyrazines. The 600-m coffee inoculated with M. caribbica showed an increase of more than one point in the score given by certified tasters. Consumers noticed the M. caribbica inoculation in the 300- and 600-m-elevation coffees. M. caribbica is a promising starter culture for Conilon coffee with the potential to increase the beverage quality.
Topics: Chromatography, High Pressure Liquid; Coffea; Coffee; Fermentation; Flavoring Agents; Gas Chromatography-Mass Spectrometry; Humans; Seeds; Taste; Volatile Organic Compounds; Yeasts
PubMed: 33875214
DOI: 10.1016/j.fm.2021.103786 -
Current Research in Food Science 2023Wheat-gluten, the protein-rich portion of wheat, can be processed to produce a highly savory sauce product after solid and liquid-state fermentation (SSF and LSF) with...
Wheat-gluten, the protein-rich portion of wheat, can be processed to produce a highly savory sauce product after solid and liquid-state fermentation (SSF and LSF) with the inoculation of selected lactic acid bacteria (LAB) and yeast under salt-free condition. However, limited research has been done on the impact of different types of microbes in this process. This work studied the flavour impact on fermented wheat-gluten by the single inoculation of or one yeast ( or ). Glucose was depleted during LSF in all treatments. Lactic acid production increased over time in -fermented samples but not in yeast-fermented samples. Cysteine, serine and arginine remained low over LSF in -fermented samples but increased in yeast-fermented samples. More fruity esters such as isoamyl acetate and isobutyl acetate were detected in samples fermented by , while boosted the production of alcohols such as 3-methyl butanol and 2-phenylethyl alcohol. Principal component analysis revealed a clear difference in volatile profiles of the samples fermented with different strains. Therefore, the fermented sauce can potentially be processed into different flavor directions, and based on the flavor profile, be used in different food applications.
PubMed: 37033740
DOI: 10.1016/j.crfs.2023.100492 -
Pest Management Science Jan 2023Host plant-microbe associations mediate interspecific interactions amongst herbivorous insects. However, this theory has rarely been ecologically verified in tephritid...
BACKGROUND
Host plant-microbe associations mediate interspecific interactions amongst herbivorous insects. However, this theory has rarely been ecologically verified in tephritid fruit flies. Research on this subject can not only help predict tephritid species invasion and occurrence patterns, but also develop potential novel lures for the control of the tephritid fruit fly pests. Recently, we observed mixed infestation of Bactrocera minax and Bactrocera dorsalis larvae in citrus orchards, which prompted us to explore the underlying mechanism.
RESULTS
Following oviposition by B. minax, the yeast Pichia kluyveri translocated to and proliferated inside the citrus fruit. The level of d-limonene released from citrus fruits containing P. kluyveri was 27 times higher than that released from healthy fruits. Mature B. dorsalis females were attracted to d-limonene and oviposited into fruits previously infested by B. minax. Furthermore, the interspecific interaction between B. dorsalis and B. minax within the same fruit significantly decreased the number of surviving larvae and pupal weight in B. dorsalis, but its effect on B. minax was weaker.
CONCLUSION
In the studied interspecific interaction, B. minax occupies the dominant position, implying ecological significance for this species in terms of consolidating its own niche and inhibiting the invasion of exotic species. To our best knowledge, this is the first report from both ecological and physiological perspectives on a symbiotic yeast mediating the interaction between B. minax and B. dorsalis through altering fruit volatiles. © 2022 Society of Chemical Industry.
Topics: Saccharomyces cerevisiae
PubMed: 36177948
DOI: 10.1002/ps.7211 -
Microbiological Research Apr 2021A diversity of yeasts and lactic bacteria were isolated from the feces of ring-tailed coaties bred in captivity and related to the production of "misha coffee"....
Isolation of microorganisms from the feces of ring-tailed coati related to the production of "misha coffee" in the central forest of Peru and evaluation of some features of technological importance.
A diversity of yeasts and lactic bacteria were isolated from the feces of ring-tailed coaties bred in captivity and related to the production of "misha coffee". Isolation of yeasts was carried out using oxytetracycline-glucose-yeast extract agar containing 100 mg/L oxytetracycline and, lactic bacteria using de Man-Rogosa and Sharpe agar containing 20 mg/L of vancomicin. Then, isolates were biochemically analysed using API strips (ID 32C for yeasts and 50CHL for lactic bacteria) followed by 16S and 26S rRNA gene sequencing. Among the yeasts, Debaryomyces hansenii, Pichia kluyveri, Pichia kudriavzevii, and Candida sorboxilosa were the most frequent, whereas Weissella cibaria, Weissella paramesenteroides, Enterococcus thailandicus and Enterococcus faecalis were the most important lactic bacteria. Cultivation of the isolated yeasts under agitated conditions, showed that Pichia kluyveri LBFT.Lev3 (0.15 ± 0.01 h) and Pichia kudriavzevii LBTF.Lev7 (0.14 ± 0.01 h) had higher specific growth rates than Debaryomyces hansenii LBFT.Lev9 (0.09 ± 0.01 h), whereas cultivation of lactic bacteria under static fashion showed that Weisella paramesenteroides LBTF.Bal2 (0.16 ± 0.01 h) and Weisella cibaria LBTF.Bal3 (0.18 ± 0.01 h) had better growth than Enterococcus thailandicus LBTF.Bal1 (0.1 ± 0.015 h) and Enterococcus faecalis LBTF.Bal7 (0.14 ± 0.01 h). Additionally, evaluation of pectinolytic activity revealed that Pichia kudriavzevii LBTF.Lev7 and Debaryomyces hansenii LBFT.Lev9 were able to use pectin as carbon source for their growth. On the other hand, W. cibaria LBTF.Bal3, E. thailandicus LBTF.Bal1 and W. paramesenteroides LBTF.Bal2 showed inhibitory activity against S. mutans ATCC 35668, B. subtilis subsp. spizizenii ATCC 6633 and Staph. epidermidis ATCC 14990. Results of this study are useful for the search of potential application of the isolated yeasts and lactic bacteria in coffee and other food fermentations.
Topics: Animals; Bacteria; Coffee; Feces; Food Microbiology; Forests; Peru; Procyonidae; Yeasts
PubMed: 33418399
DOI: 10.1016/j.micres.2020.126670 -
Frontiers in Microbiology 2019Effects of wine and dairy yeast fermentation on chemical constituents of tilapia fish head hydrolysate supplemented with glucose in an unsalted and acidic environment...
Effects of wine and dairy yeast fermentation on chemical constituents of tilapia fish head hydrolysate supplemented with glucose in an unsalted and acidic environment were investigated. Three wine yeasts ( Biodiva, Lalvin EC-1118 and Frootzen) and one dairy yeast ( NCYC1425) were employed as single starter cultures, respectively, and were compared with one soy sauce yeast ( NCYC1433). Each yeast showed different growth kinetics and fermentation performance. Compared with NCYC1433, other yeasts presented a significant higher rate of glucose consumption ( < 0.05). Besides, NCYC1425 and Frootzen produced more citric acid and succinic acid, respectively, while Lalvin EC-1118 exhibited higher pyruvic acid production. Significant lower levels of total free amino acids were observed in samples inoculated with wine yeasts relative to other yeasts ( < 0.05). Non-soy sauce yeasts produced increased various levels of esters and alcohols without traditional fish sauce unpleasant odorants, especially NCYC1425 and Frootzen. The results confirmed that non-soy sauce yeasts are suitable for fish sauce flavor compound modification and to develop a fast fermentation process for saltless fish sauce from fish head, which could increase the acceptability of fish sauce and improve the utilization of fish by-products.
PubMed: 31649641
DOI: 10.3389/fmicb.2019.02300 -
Journal of Water and Health May 2023Cockroaches are known as mechanical vectors of some pathogens that can infect humans. The present study aims to rapidly identify Periplaneta americana fungal pathogens...
Cockroaches are known as mechanical vectors of some pathogens that can infect humans. The present study aims to rapidly identify Periplaneta americana fungal pathogens from sewer systems of public hospitals in Esfahan using the polymerase chain reaction (PCR) technique. A total of 55 P. americana cockroaches were randomly collected by direct trapping from sewer systems of seven hospitals and screened for fungal infectious agents using standard morphological methods and the PCR sequencing. From the American cockroach, we isolated 62 yeasts and 31 molds from the surface, hemocoel, and digestive tract of P. americana. Based on DNA sequence comparisons and other taxonomic characteristics, they were identified as more than four species of yeast and four species of mold. Yeast species including Pichia kudriavzevii, Candida glabrata, Pichia kluyveri, and Candida viswanathii, and molds such as Aspergillus niger, Penicillium italicum, Mucor plumbeus, and Rhizopus oryzae were isolated repeatedly from the surface, hemocoel, and digestive tract of P. americana. Our results show that the use of a combination of morphological, molecular techniques, and phylogenetic analysis can lead to the identification of pathogenic fungal agents in American cockroaches and also knowledge of fungal pathogens-arthropod host relationships.
Topics: Animals; Humans; Cockroaches; Periplaneta; Phylogeny; Fungi; Hospitals
PubMed: 37254911
DOI: 10.2166/wh.2023.015 -
FEMS Microbiology Letters Nov 2021Non-Saccharomyces yeasts are important players during winemaking and may come from grapes grown in vineyards. To study the diversity of non-Saccharomyces yeasts on grape...
Non-Saccharomyces yeasts are important players during winemaking and may come from grapes grown in vineyards. To study the diversity of non-Saccharomyces yeasts on grape berry surfaces, 433 strains were isolated from different Cabernet Sauvignon vineyards grown in Henan Province. Our results demonstrated that these strains were classified into 16 morphotypes according to their growth morphology on Wallerstein Laboratory agar medium, and were identified as seven species from four genera-Hanseniaspora opuntiae, Hanseniaspora vineae, Hanseniaspora uvarum, Pichia occidentalis, Pichia kluyveri, Issatchenkia terricola and Saturnispora diversa-based on a series of molecular biological experiments. Hanseniaspora opuntiae was obtained from all sampling sites except Changyuan County, while Pichia kluyveri and Saturnispora diversa were only found in sites of Zhengzhou Grape Resource Garden and Minquan County, respectively. The site Minquan was home of the greatest species richness, while only one single species (Hanseniaspora opuntiae) was detected at NAPA winery from Zhengzhou or at Anyang County. Finally, this study suggested that the geographic distribution and diversity of non-Saccharomyces yeast populations on Cabernet Sauvignon grape berries were likely to be determined by a combination of grape varieties and environmental factors.
Topics: Biodiversity; China; Farms; Fermentation; Fruit; Hanseniaspora; Pichia; Saccharomycetales; Vitis; Wine; Yeasts
PubMed: 34755861
DOI: 10.1093/femsle/fnab142