Identification Of Yeasts Research Articles

Isolation and characterisation of dominant acetic acid bacteria and yeast isolated from Kombucha samples at point of sale in New Zealand

The demand for Kombucha, a sparkling sugared tea beverage fermented by a symbiotic culture of acetic acid bacteria (AAB) and yeast is increasing worldwide. Despite the popularity of the beverage which is mainly due to its perceived health benefits and appealing sensory properties, the microbial composition of the products at the time of consumption is unknown. Such information is important to both manufacturers and consumers. Therefore, this study characterised the dominant AAB and yeast present in six commercial Kombucha samples sold in New Zealand which comprised of three domestic and three imported samples. Acetic acid bacteria and yeast were isolated from the Kombucha samples using glucose yeast extract peptone mannitol (GYPM) and yeast extract glucose chloramphenicol (YGC) media, respectively. Phenotypic and taxonomic identification of AAB and yeast were achieved by morphological and biochemical characterisation, followed by sequence analysis of ribosomal RNA genes (16S rRNA for AAB and 26S rRNA for yeast). Viable AAB and yeast were only found in domestically produced Kombucha samples and not in the imported products. The dominant AAB species were identified as Acetobacter musti and Gluconobacter potus. The yeast isolates belonged to Dekkera bruxelensis, Schizosaccharomyces pombes, Hanseniaspora valbyensis, Brettanomyces anamalus, Pichia kudriavzevii, Starmerella vitis and Saccharomyces cerevisiae. The yeast communities were more complex and variable than the AAB communities in the analysed Kombucha samples.

Medically important Candida spp. identification: an era beyond traditional methods.

Candida infections are gaining more attention for the last few decades so diagnostic tools are very important for early diagnosis. Conventional identification of yeasts is time-consuming, molecular methods are more complicated and relatively expensive gold-standard methods. Matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF MS) was put into the market due to its speed and high accuracy. The aim of this study was to evaluate the performance of corn meal tween-80 agar (CMTA), CHROMagar Candida medium, and MALDI-TOF MS and to compare the obtained results with DNA sequencing. The CHROMagar Candida medium, CMTA, and MALDI-TOF MS Biotyper System were used to test 416 isolates. The isolates with discrepant results by at least one of the three methods were subjected to sequence analysis. The identification results of the 351 (%84.4) were compatible with all three methods. When compared to the sequencing results, the most accurate results were obtained by the MALDI-TOF MS, especially for rare Candida species. MALDI-TOF MS is found to be the most accurate identification tool for clinically important Candida strains. CMTA alone should not be used for the final identification of Candida species and the chromogenic medium should always be considered presumptive.

Ecology and population dynamics of yeast starter cultures in cocoa beans fermentation.

This study aimed to investigate controlled fermentation of cocoa beans with selected yeasts as starter cultures via integrating microbiological, biochemical, and chromatographic analyses. The steps involved in the yeast starter culture test were of the following order: 1) counting, isolation, purification, and biochemical identification of yeasts, 2) selection of ethanol-producing yeasts, 3) selection of thermotolerant yeasts, and 4) evaluation of physicochemical parameters of the selected yeasts in controlled fermentation of cocoa (F1 - Saccharomyces ssp. and Hanseniaspora ssp. and F2 - spontaneous fermentation - control). A total of 32 yeasts were isolated from three sampling points (M1, M2, and M3), which comprised 50% Candida ssp., 9.4% Rhodotorula ssp., 18.8% Saccharomyces ssp., and 18.8% Hanseniaspora ssp. The yeasts identified as Saccharomyces ssp. (n = 6) were subjected to the ethanol production test. Saccharomyces spp. CLV09 showed the highest concentration of ethanol in the simulated cocoa medium (3.5% v/v). Hanseniaspora spp. CVL20 and CVL19 strains showed the highest thermotolerance at 42°C after 72 h of growth. The starter cultures with Saccharomyces ssp. and Hanseniaspora ssp. showed a similar growth rate of the mesophilic aerobic population in both F1 and F2. Fermentation of the starter culture showed a higher production of organic acids than spontaneous fermentation (F2). Thus, Saccharomyces ssp. and Hanseniaspora ssp. can be used as a starter culture in cocoa fermentation.

Antibacterial activities of indigenous yeasts isolated from pomegranate peels (Punica granatum L.).

Pomegranate peels (PGPs) are known to have the potential as antibacterial not only from their nutrient content but also the microflora. The activities might be caused by the existence of indigenous yeast that can be utilized to inhibit the growth of pathogenic bacteria. This study aims to identify antibacterial and antioxidant activity of indigenous yeast isolated from PGP. The research was conducted by experimental methods and followed by descriptive analysis. The study was done by the isolation of indigenous yeast from PGPs, which was identified using the rRNA sequence analysis of internal transcribed spacer (ITS) region with the primers of ITS1 (5′-TCCGTAGGTGAACCTGCGG-3′) and ITS4 (5′-TCCTCCGCTTATTGATATGC-3′) and then compared with Basic Local Alignment Search Tools (BLAST) algorithm toward the GenBank. Antibacterial activities of indigenous yeast were tested with agar plug diffusion and time kill test toward Escherichia coli and Staphylococcus aureus. The yeast identification obtained two isolates similar to Hanseniaspora uvarum CBS 314 and two isolates of Pichia kudriavzevii ATCC 6258 which have antibacterial activity against E. coli and S. aureus. P. kudriavzevii PGP D4 have best antimicrobial activities with a strong activity against E. coli (±9 mm) and medium activity against S. aureus (±3.1 mm).

Screening and Identification of Yeasts from Fruits and Their Coculture for Cider Production

Coculturing non-Saccharomyces yeasts with Saccharomyces cerevisiae could enrich the aromatic complexity of alcoholic beverages during cider brewing. Therefore, the present study performed rapid strain screening via selective culture medium and aroma analysis and adopted a response surface methodology to optimize fermentation conditions to produce 2-phenylethyl acetate (PEA), which presents a rose and honey scent. The effects of coculturing yeasts on cider quality were evaluated through hedonic sensory analysis and the check-all-that-apply (CATA) method. Hanseniaspora vineae P5 and S. cerevisiae P1 produced ciders with high levels of PEA and 2-phenylethanol, respectively. The optimal fermentation process consisted of sequential inoculation with a 31 h delay between inoculations, followed by fermentation for 14.5 d at 18.7 °C, yielding 17.41 ± 0.51 mg/L of PEA, which was 4.6-fold higher than that obtained through the unoptimized fermentation process. Additionally, the CATA results revealed that the cider produced through coculturing was associated with descriptors such as “smooth taste”, “honey”, “pineapple”, and “fruity”, which can be attributed to the high ethyl acetate and PEA levels in the cider.

Isolation and Identification of Wild Yeast from Malaysian Grapevine and Evaluation of Their Potential Antimicrobial Activity against Grapevine Fungal Pathogens.

Pathogenic fungi belonging to the genera Botrytis, Phaeomoniella, Fusarium, Alternaria and Aspergillus are responsible for vines diseases that affect the growth, grapevine yield and organoleptic quality. Among innovative strategies for in-field plant disease control, one of the most promising is represented by biocontrol agents, including wild epiphytic yeast strains of grapevine berries. Twenty wild yeast, isolated and molecularly identified from three different Malaysian regions (Perlis, Perak and Pahang), were evaluated in a preliminary screening test on agar to select isolates with inhibition against Botrytis cinerea. On the basis of the results, nine yeasts belonging to genera Hanseniaspora, Starmerella, Metschnikowia, Candida were selected and then tested against five grape berry pathogens: Aspergillus carbonarius, Aspergillus ochraceus, Fusarium oxysporum, Alternaria alternata and Phaeomoniella chlamydospora. Starmerella bacillaris FE08.05 and Metschnikowia pulcherrima GP8 and Hanseniaspora uvarum GM19 showed the highest effect on inhibiting mycelial growth, which ranged between 15.1 and 4.3 mm for the inhibition ring. The quantitative analysis of the volatile organic compound profiles highlighted the presence of isoamyl and phenylethyl alcohols and an overall higher presence of low-chain fatty acids and volatile ethyl esters. The results of this study suggest that antagonist yeasts, potentially effective for the biological control of pathogenic moulds, can be found among the epiphytic microbiota associated with grape berries.

Laboratory Diagnostic Capacity for Fungal Infections in Nigerian Tertiary Hospitals: A Gap Analysis Survey


 Background: An estimated 11.8% of Nigerians suffer from invasive fungal infections (IFIs) yearly. Laboratory capacity to diagnose IFIs in Nigeria has not been objectively assessed.
 Objective: To identify the gaps in laboratory capacity for diagnosis of IFIs in Nigerian tertiary hospitals.
 Methods: Clinical microbiologists in Nigerian tertiary hospitals were invited to partake in a 21-item online survey via a professional chat group and email. A descriptive crosssectional study of survey responses was conducted. Frequencies were computed for microscopy, culture, antifungal sensitivity, and non-culture based diagnostic modalities.
 Findings: Respondents were from 22 tertiary hospitals spread across the six geo-political zones of Nigeria. Gaps identified include absence of mycology laboratory/bench in 5/22 (22.7%), no access to a biosafety cabinet in 5/22 (22.7%), lack of laboratory scientists formally trained in mycology in 9/22 (40.9%), lack of participation in external quality assurance in all (100%), lack of automated blood culture facilities in 9/22 (40.9%), no yeast identification beyond germ tube test in12/22 (54.5%), and no anti-fungal sensitivity testing in 17/22 (77.3%). Galactomannan, cryptococcal antigen lateral flow assay and latex agglutination tests are used in 1(4.5%), 3 (13.6%) and 5 (22.7%) centres respectively; antigen/antibody based non-culture diagnostics were totally absent in 12/22 (54.5%) hospitals.
 Conclusion: Nigerian tertiary hospitals have gaps in the laboratory capacity to diagnose invasive fungal infections despite the significant size of the population at risk of these life-threatening infections in the country. Economically feasible diagnostic solutions and models as well as capacity building are urgently required.
 
 Keywords: Fungal infections; Laboratories; Nigeria; Tertiary hospital.

English

Orthodontic treatment makes necessary to use a longtime fixed-band appliance, it offers suitable conditions for fungal growth, dentures also allow fungal contamination on their surfaces. The aim of our study is the identification of the fungal species colonizing surfaces of dental appliances, the cross-sectional study was carried out on 60 patients wearing dental appliances, during 5 months, and sterile swabs were used and inoculated into Sabouraud’s dextrose agar tubes. Yeast identification has been based on germ tube test, chlamydoconidia production and biochimical tests (Auxacolor, Api 20 C). The overall prevalence of fungal contamination of dental orthodontic appliance was 35%. The prevalence rate was 40% among patients who had dental appliances for 1 to 2 months, and 45,5% fort patients brushing their teeth at least twice daily, but no statistical relation with mycosis was found. Pain, burning and discomfort were correlated to fungal carriage p=0,038; OR=4,867 IC 95% (1.09-21.74). The fungal species most recovered were Candida parapsilosis 21.47%, Candida Zeylanoides 21.47%, Candida albicans 17.38%, and Cryptococcus terreus 13.04%. Mycological monitoring of dental prosthesis is crucial to prevent possible fungal’s adverse health effects.   Key words: Orthodontic appliances, dentures, fungal contamination, Candida sp, Cryptococcus terreus.

Molecular identification and technological properties of yeasts isolated from spontaneously fermented cassava waste pulp

The aim of this work was to report on molecular identification and technological properties of the yeast flora isolated from spontaneously fermented cassava waste pulp. This was done with a view of obtaining yeast strains that could be used as a starter culture for the fermentation of cassava waste pulp. Molecular identification was based on the nucleotide sequence of the ITS region of the genomic DNA of the yeast isolates while the technological properties evaluated include linamarase (U/mL), gelatinase, and haemolytic activity; growth at pH 2.5 and tolerance to 2 % bile salt. All the representative five isolated yeasts were identified as Geotrichum silvicola KLP04 – KLP08. The isolates exhibited linamarase activity ranging between 3.3 and 4.2 with strain KLP04 having the highest value and strain KLP05 the least. None of the isolates demonstrated gelatinase and haemolytic activity except strain KLP08 which was partially haemolytic. All the examined yeasts exhibited good growth at pH 2.5, with strain KLP08 having the highest viable counts of 4.1 log10cfu/ml and strain KLP04 the least value of 3.5 log10cfu/ml after 72 h of growth. All the identified yeasts showed strain-specific tolerance to 2% bile salt with strain KLP04 having the highest viable count of 4.3 log10cfu/ml and strain KLP08 the least value of 2.2 log10cfu/ml at the end of 72 h of incubation. Based on all the examined technological properties, Candida silvicola KLP04 strain had the highest potential to be considered for starter culture for the fermentation of cassava waste pulp.

Screening, Characterization and Identification of Sophorolipid-Producing Yeast Isolated from Palm Oil Effluent Polluted Soil

Aim: This study investigated the screening, characterization and identification of sophorolipid-producing yeast isolated from palm oil effluent polluted soil.
 Place and Duration: Two soil samples impacted with palm oil mill effluent were obtained from Elibrada and Rumuche in Emohua Local Government Area, Rivers State, Nigeria, between March 2020 and September 2021.
 Methodology: The soil samples were analyzed for physicochemical, geotechnical and microbiological qualities. The yeast isolates were identified using biochemical and 16S ITS molecular approaches. The isolates were screened for hydrocarbon degradation and sophorolipid production. The sophorolipid production was evaluated using emulsification index (E24), haemolytic activity, oil spread activity, drop collapse and blue agar plate assay (Cetyl trimethyl ammonium bromide CTAB Method).
 Results: The pH of the Palm oil mill effluent -impacted soil ranged between pH 6.18 to 6.34 the electrical conductivity value for Elibrada and Rumuche were 20.84 µS/cm and 80.19 µS/cm respectively while that of the unpolluted soil was 220.13 µS/cm. Permeability of the soil from Elibrada was 2.7 cm/s, Rumuche had 1.3 cm/s while the unpolluted soil had 5.6 cm/s. Total organic carbon for soil samples from Rumuche was 4.92%, Elibrada had 6.13% while the unpolluted soil had 8.74%. Oil and grease component for the Rumuche soil was 10500 mg/kg, Elibrada had 7200 mg/kg and the unpolluted soil had 28.0 mg/kg. Total fungal count for Rumuche soil samples was 3.8 × 104 CFU/g while Elibrada had 3.2 × 104 CFU/g. Eighty percent (80%) of the isolates were Candida spp. while 20% were Saccharomyces sp. There were four bands separated which were denoted as ITS 600bp and a Ladder L which was 500bp. The phylogenetic construct showed that the Y8 was 70.2% similar to Candida parapsilosis. The isolate Y3 was 95.8% similar to Candida haemulonis. Isolate Y9 had 100% similarity with Pichia kudriavzevii while Y13 had a 97.4% identity with Saccharomyces cerevisiae the GENBANK accession numbers were Candida haemulonis MW182014, Candida parapsilosis MW182015, Pichia kudriavzevii MW182016 and Saccharomyces cerevisiae MW182017.
 Conclusion: There is an increasing concern to develop a process for microbial isolation and characterization for effective biotechnological advancement using impacted environmental media as a bioresource.

Isolation, identification, and characterization of wild budding yeasts from rose flowers in Fukuyama city, Hiroshima, Japan, and their application in bread and wine production.

In this study, we isolated 741 wild budding yeast strains from the flowers of 45 rose cultivars growing in Fukuyama city, Hiroshima, Japan. Of these 741 strains, 21 were found to have high fermentation abilities in yeast extract-peptone-dextrose (YPD) medium. Four of the 21 strains were able to ferment bread dough to make bread. These yeasts were identified as Saccharomyces cerevisiae, Lachancea fermentati, Lachancea kluyveri, and a Torulaspora sp. based on DNA sequences from the 26S rDNA D1/D2 regions. The CO2 production profiles of the bread dough generated by the rose yeasts were evaluated using a Fermograph. Saccharomyces cerevisiae FRY2915 exhibited the highest fermentation capacity. Furthermore, FRY2915 was able to ferment grape juice to produce wine, yielding an alcohol concentration of more than 12%. The four rose yeasts isolated during this study have the potential to produce various types of unique fermented foods, thus enhancing the value of the microbiota associated with rose flowers.

Identification and technological characterization of endogenous yeast isolated from fermented black carrot juice, shalgam

Shalgam is a fermented beverage obtained by lactic acid fermentation and its quality depends on flora. Therefore, it is essential to be able to characterize yeasts, in order to improve the quality and safety controls of final products. This study aimed to identify endogenous yeasts found during the fermentation of shalgam and to determine their technological properties. 172 yeast isolates were obtained and the DNA fingerprints were constituted by iPBS-PCR method. Sequencing of ITS regions of different groups revealed the species of Pichia kudriavzevii, P. fermentans, Saccharomyces cerevisiae, Candida oleophila, Kazachstania bulderi, and Geotrichum candidum. Interestingly, the prevalence of P. kudriavzevii in the flora increased during the fermentation, while the other species decreased. To determine the preliminary technological properties of yeasts, their development at different conditions was examined and 31 technologically superior strains were determined by Principal Component Analysis (PCA). Among these, 17 P. kudriavzevii strains had a vigorous fermentation rate and selected to assess their enzymatic activity. The isolates had diverse enzyme activities, including esterase, esterase lipase, and leucine arylamidase, which may have crucial roles for aroma formation. According to the results, P. kudriavzevii 3-3S9, 3-3S2, and 3-3Y1 strains were selected to be candidate starters for shalgam production.

PATTERNS OF ANTIMICROBIAL RESISTANCE AMONG MAJOR BACTERIAL PATHOGENS ISOLATED FROM CLINICAL SAMPLES IN TWO TERTIARY’S HOSPITALS, IN SANA'A, YEMEN

Background and objectives: At the present time, antimicrobial resistance (AMR) is a major public health hazard, with antimicrobial resistance bacteria increasing exponentially. This study estimates the epidemiological profiles and antimicrobial resistance of Gram-positive bacteria (GPB) and Gram-negative bacteria (GNB) isolated from clinical samples among patients admitted to two University hospitals in Sana'a city for one year (2019). Methods: This was a retrospective study of clinical samples of patients collected from January 1, 2019 to December 30, 2019. All samples were appraised to determine presence of infectious agents using standard methods for isolation and identification of bacteria and yeasts from clinical samples of patients admitted to Al-Gumhouri University Hospital and Al-Kuwait University Hospital in Sana'a city. Antibiotic resistance was done using Kirby-Bauer disc diffusion methods. Results: 2,931 different pathogenic bacteria were detected from 24,690 different clinical specimens. The samples had an overall detection rate of 11.9% (2931/24,690). Among the bacterial pathogens isolated from clinical samples, 52.4% (n=1536) had GPB and 41.2% (n=1207) had GNB. The predominant GNB isolates were E.coli (22.04%), Klebsiella spp (6.03%), Pseudomonas aeruginosa (7.1%), Acinetobacter baumannii (1.46%), Enterobacter spp. (1.09%), Citrobacter spp. (1.16%), respectively. Among the GPB, S.aureus was the most common (26.3%), Coagulase-negative Staphylococcus (8.1%), Non-hemolytic Streptococcus (9.1%), Other alpha-hemolytic Streptococcus (3.9%), Streptococcus pyogenes (1.9%), and Streptococcus pneumoniae (0.5% ). A high rate of antibiotic resistance was recorded for sulfamethoxazole/trimethoprim (85.5%), ceftazidime (81.07%), ampicillin (70.4%), cefuroxime (66.4%). Conclusions: The current study results revealed that the rate of resistance between GNB and GPB is associated with the incidence of different infections in patients attending two major tertiary hospitals in Sana'a city is very high. These results indicate ongoing screening and follow-up programs to detect antibiotic resistance, and also suggest the development of antimicrobial stewardship programs in Sana'a, Yemen. Peer Review History: Received: 9 September 2021; Revised: 11 October; Accepted: 23 October, Available online: 15 November 2021 Academic Editor: Dr. A.A. Mgbahurike, University of Port Harcourt, Nigeria, amaka_mgbahurike@yahoo.com UJPR follows the most transparent and toughest ‘Advanced OPEN peer review’ system. The identity of the authors and, reviewers will be known to each other. This transparent process will help to eradicate any possible malicious/purposeful interference by any person (publishing staff, reviewer, editor, author, etc) during peer review. As a result of this unique system, all reviewers will get their due recognition and respect, once their names are published in the papers. We expect that, by publishing peer review reports with published papers, will be helpful to many authors for drafting their article according to the specifications. Auhors will remove any error of their article and they will improve their article(s) according to the previous reports displayed with published article(s). The main purpose of it is ‘to improve the quality of a candidate manuscript’. Our reviewers check the ‘strength and weakness of a manuscript honestly’. There will increase in the perfection, and transparency. Received file: Reviewer's Comments: Average Peer review marks at initial stage: 6.0/10 Average Peer review marks at publication stage: 7.5/10 Reviewers: Rima Benatoui, Laboratory of Applied Neuroendocrinology, Department of Biology, Faculty of Science, Badji Mokhtar University Annaba, BP12 E L Hadjar–Algeria, benattouiryma@gmail.com Dr. Wadhah Hassan Ali Edrees, Hajja University, Yemen, edress2020@gmail.com Rola Jadallah, Arab American University, Palestine, rola@aauj.edu Similar Articles: PREVALENCE OF PSEUDOMONAS AERUGINOSA (P. AERUGINOSA) AND ANTIMICROBIAL SUSCEPTIBILITY PATTERNS AT A PRIVATE HOSPITAL IN SANA'A, YEMEN EVALUATION OF ANTIBACTERIAL RESISTANCE OF BIOFILM FORMS OF AVIAN SALMONELLA GALLINARUM TO FLUOROQUINOLONES

Isolation and Identification of Aroma-producing Yeast from Mackerel Fermentation Broth and Its Fermentation Characteristics

ABSTRACT In order to obtain microbial starter cultures for aroma enhancement of fish sauce, aroma-producing yeasts from mackerel fermentation broth were isolated, screened and identified by morphological characterization and ITS rDNA sequence analysis. The results showed that seven yeast strains were isolated, of which six strains were Lodderomyces elongisporus and one was Wickerhamomyces anomalus. The volatile compounds of mackerel enzymatic hydrolysate fermented by the yeasts were analyzed by headspace solid phase micro extraction and gas chromatography coupled with mass spectrometry (HS-SPME/GC-MS). The results indicated that the main volatile compounds were aldehydes, ketones, alcohols, esters, hydrocarbons, acids and heterocycles in the fermentation broths, rendering the special aroma and flavor of fish sauce. In addition, the growth assay, salt tolerance and temperature resistance of the two yeast strains were determined, which was found that the strains exhibited excellent salt tolerance and temperature resistance. For the first time, Wickerhamomyces anomalus and Lodderomyces elongisporus were separated from the aquatic products, exhibiting enormous potential in the application of the aroma-enhancing for fish sauce.

Isolation and Identification of Fungi from Clinical Samples of Diabetic Patients and Studying the Anti-Fungal Activity of Some Natural Oils on Isolated Fungi

Isolation of fungi was performed from February to July, 2019. One hundred clinical specimens were collected from King Abdullah Hospital (KAH) Bisha, Saudi Arabia. Samples were collected from twenty patients of different ages (30 - 70 years old) ten males and ten females. The samples were collected from patients with the two types of diabetics. Specimens included blood, hair, nail, oral swabs and skin. Specimens were inoculated on Sabourauds Dextrose agar containing chloramphenicol. Thirteen fungal species were isolated and identified. The isolated species were: Aspergillus flavus, A. niger, A. terrus, A. nidulans, A. fumigatus, Candida albicans, C. krusei, C. parapsilosis, C. Tropicalis, Curvularia lunata, Fusarium solani, Penicillium marneffei and Saccharomyces cerevisiae. Identification of molds was carried out morphologically and microscopically using available methods and books of identification, while identification of yeasts was carried out using API system. C. albicans recorded the highest isolated number where 31 colonies were isolated from 18 patients, representing relative density of 22.5%. (R. D.: is the number of a certain fungal species divided by the total number of fungi). Other isolated fungal species recorded relative density less than 16 %. The most common isolated fungus Candida albicans was molecularly identified using the 5.8S and flanking ITS regions. The antifungal activity of some natural essential oils (cinnamon, thyme, coconut, almond and clove) was assayed against isolated fungi using disk diffusion method. The used concentration was 5 µl / plate. The MIC values were also determined using different oil concentrations (1, 2.5, 5, 10, 20 and 40 µl / disc).

Isolation and Identification of Yeasts in White Cheese

In this study, firstly yeast was isolated from 50 white cheese samples produced by traditional methods from raw milk. The yeast species were isolated from 50 traditional white cheese samples and identified with the VITEK2 Compact system. There were obtained from white cheese samples 90 isolates 35.6% Candida sake (32), 13.3% Candida zeylanoides (12), 8.9% Candida famata (8) and 8.9% Candida kefyr (8) and the remaining 33.3% Candida sphaerica (4), Candida colliculasa (2), Candida boidinii (2), Candida lusitaniae (4), Candida parapsilosis (2), Candida sphaerica (4) Cryptococcus laurentii (4), Candida krusei (4) and Saccharomyces cerevisiae (4). Yeasts are known as a saprophyte found in many foods, but that some of them positively contribute to the fermentation. More over some yeasts are could used of starter culture during the manufacture of certain dairy product for maturation by supporting the functions. some yeasts species were isolated in this study, could be used as support culture.

Identification of lactic acid bacteria and yeasts from traditional sourdoughs and sourdough production by enrichment

The subject of this study was to investigate lactic acid bacteria (LAB) and yeasts microbiota of traditional sourdough (n = 36) and to indicate characteristics of enriched sourdough that is produced from combinations of isolates. A total of 60 LAB and 40 yeasts were identified from sourdough by matrix-assisted laser desorption ionisation-time-of-flight mass spectrometry (MALDI-TOF MS) analysis. The dominant LAB microflora was Lactobacillus brevis (43.33%), Pediococcus acidilactici (21.67%) and Lactobacillus plantarum (18.33%). The dominant yeasts microflora was Saccharomyces cerevisiae (27.5%), Pichia kudriavzevii (25.0%) and Kluyveromyces marxianus (12.5%). The sourdough prepared with the combination of L. brevis, Leuconostoc mesenteroides, P. acidilactici and S. cerevisiae, K. marxianus showed the best physicochemical and microbiological properties while that with L. plantarum, L. brevis and P. kudriavzevii, Wickerhamomyces anumalus was the poorest. LAB and yeasts in the sourdoughs were ranged from 6.58 log CFU g<sup>–1 </sup>to 9.12 log CFU g<sup>–1</sup> and from 6.12 log CFU g<sup>–1</sup> to 7.88 log CFU g<sup>–1</sup>, respectively. Various chemical parameters such as pH, total titratable acidity (TTA), ethanol, and sourdough volume were differ depending on the type of microbial species. TTA was more pronounced in the sourdoughs produced with homofermentative LAB. Yeasts and LAB were dominated during continuous enriching of sourdough, supporting an important role during fermentation.

Saccharification and Fermentation of Cellulolytic Agricultural Biomass to Bioethanol using Locally Isolated Aspergillus niger S48 and Kluyveromyces sp. Y2, respectively

Due to increase in demand for energy as a result of human population explosion, industrialization and environmental hazards posed by fossil fuels, there is a need to source for alternative energy sources that are cheaper and environmental friendly. Three different lignocellulosic biomasses were studied for their suitability for bioethanol production. Fungi and yeasts were isolated using serial dilution and spread plate methods. Identification of both fungi and yeasts was done using their cultural and microscopy characteristics. Saccharification of the pre-treated biomass was done with both crude cellulase and mycelia inoculant. Bioethanol was produced using batch culture fermentation. Ethanol produced was detected using spectrometric method and quantified using High Performance Liquid Chromatography (HPLC). The effects of substrate concentration, pH and temperature on ethanol yield were optimized. Fifty fungal isolates were obtained from soil collected. Six yeasts, all Kluyveromyces species fermented three sugars to ethanol with isolate Kluyveromyces sp.Y2 having the shortest time. It was selected for fermentation. Aspergillus niger S48 had highest cellulase activity measured in a zone of hydrolysis of 26.0 mm. It had the highest glucanase activity, endoglucanase (0.462 U/mL) and exoglucanase (0.431 U/mL). The outcome of this study indicated that crude cellulase produced by Aspergillus niger S48 hydrolyzed the pre-treated rice chaff with 1.07 mg/mL of fermentable sugars higher than 0.87 mg/mL when the mycelia of the fungus was inoculated to pretreated rice chaff for hydrolysis. Ethanol was optimally produced at 12 % substrate concentration using rice chaff, at a temperature of 35 °C and pH 5.0.

Application of Micropore Device for Accurate, Easy, and Rapid Discrimination of Saccharomyces pastorianus from Dekkera spp.

Traceability analysis, such as identification and discrimination of yeasts used for fermentation, is important for ensuring manufacturing efficiency and product safety during brewing. However, conventional methods based on morphological and physiological properties have disadvantages such as time consumption and low sensitivity. In this study, the resistive pulse method (RPM) was employed to discriminate between Saccharomyces pastorianus and Dekkera anomala and S. pastorianus and D. bruxellensis by measuring the ionic current response of cells flowing through a microsized pore. The height and shape of the pulse signal were used for the simultaneous measurement of the size, shape, and surface charge of individual cells. Accurate discrimination of S. pastorianus from Dekkera spp. was observed with a recall rate of 96.3 ± 0.8%. Furthermore, budding S. pastorianus was quantitatively detected by evaluating the shape of the waveform of the current ionic blockade. We showed a proof-of-concept demonstration of RPM for the detection of contamination of Dekkera spp. in S. pastorianus and for monitoring the fermentation of S. pastorianus through the quantitative detection of budding cells.

The influence of growth conditions on MALDI-TOF MS spectra of winemaking yeast: implications for industry applications

Previous studies have shown MALDI-TOF MS to be a powerful tool in wine yeast identification and potential prediction of application. However, it is also established that substrate composition influences protein expression, but the degree to which this may affect MALDI-TOF spectra (and analytical results thereof) has not been fully explored. To further inform assay optimisation, the influence on MALDI-TOF spectra was determined using eight Saccharomyces strains of diverse origins cultivated on grape juices from Pinot Noir and Chardonnay varieties, synthetic grape juice, and laboratory-grade artificial culture media (YPD broth and agar). Our results demonstrated significant influences of culture media on strain MALDI-TOF spectra. Yeast culture on YPD agar is recommended for taxonomic studies, with YPD broth culture of S. cerevisiae offering improved intra-subspecific differentiation Furthermore, our data supported a correlation between MALDI spectra and the potential industrial application of individual yeast strains.