Displaying publications 1 - 20 of 63 in total

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  1. Emami Moghaddam SA, Harun R, Mokhtar MN, Zakaria R
    Biomed Res Int, 2018;2018:6563196.
    PMID: 30643814 DOI: 10.1155/2018/6563196
    The interest in utilizing algae for wastewater treatment has been increased due to many advantages. Algae-wastewater treatment system offers a cost-efficient and environmentally friendly alternative to conventional treatment processes such as electrocoagulation and flocculation. In this biosystem, algae can assimilate nutrients in the wastewater for their growth and simultaneously capture the carbon dioxide from the atmosphere during photosynthesis resulting in a decrease in the greenhouse gaseousness. Furthermore, the algal biomass obtained from the treatment process could be further converted to produce high value-added products. However, the recovery of free suspended algae from the treated effluent is one of the most important challenges during the treatment process as the current methods such as centrifugation and filtration are faced with the high cost. Immobilization of algae is a suitable approach to overcome the harvesting issue. However, there are some drawbacks with the common immobilization carriers such as alginate and polyacrylamide related to low stability and toxicity, respectively. Hence, it is necessary to apply a new carrier without the mentioned problems. One of the carriers that can be a suitable candidate for the immobilization is zeolite. To date, various types of zeolite have been used for the immobilization of cells of bacteria and yeast. If there is any possibility to apply them for the immobilization of algae, it needs to be considered in further studies. This article reviews cell immobilization technique, biomass immobilization onto zeolites, and algal immobilization with their applications. Furthermore, the potential application of zeolite as an ideal carrier for algal immobilization has been discussed.
    Matched MeSH terms: Yeast, Dried
  2. Ilias, N.N., Jamal, P., Sulaiman, S., Jaswir, I., Ansari, A.H., Azmi, A.S., et al.
    MyJurnal
    Bioprotein is one of the useful products obtained from biotechnology invention. It is a promising replacement for the commercial fish feed supplement. In this study, the enrichment of the bioprotein content after solid state fermentation using palm kernel cake and seaweed by the white rot fungus: Phanerochaete chrysoporium and yeast: Candida utilis was carried out. The growth media components were selected from 11 types of media using Plackett-Burman design (hereinafter PBD) and were optimized by one-factor-at-a-time (OFAT) method with bioprotein concentration (mg/g) as the response. From the screening result using PBD, three media components, namely K2HPO4, CuSO4.5H2O and MnSO4.H2O were selected for further optimization using OFAT method because of their positive contributions to the response. The final results showed that 5.0 g/L K2HPO4, 3.0 g/L CuSO4.5H2O and 0.1 g/L MnSO4.H2O were there to be the optimum media constituents with 9.0 g/L, MgSO4.7H2O, 0.1 g/L, CaCl2.H2O, 3.0 g/L FeSO4.7H2O and 3.0 g/L peptone as fixed compositions. At this optimum concentration, the protein increment of 11% was observed as compared to the results determined in the screening using PBD. The study revealed the benefits of using mixed cultures in improving the protein concentrations which can be used as nutritious fish feed.
    Matched MeSH terms: Yeast, Dried
  3. Adeeb, N., Nur-Azurah, A.G., Ong, F.B., Seri, S.S., Shamsuddin, K., Noor-Aini, M.Y., et al.
    Medicine & Health, 2008;3(1):59-68.
    MyJurnal
    Cancers of the breast and cervix made up 30.4% and 12% of all cancer cases in Malaysia. Thus screening for reproductive organ cancers as women approached menopause becomes exceedingly important. The study reports the baseline assessment tests of 495 disease free urban Malaysian women aged 45 years and above who volunteered in a healthy lifestyle intervention study. The sample comprised of 58.0% premenopaused and 42.0% postmenopaused women with an average age of 51.27±5.35 years old. Over two thirds were Chinese followed by Malays and Indians. Overall, abnormal Pap smears were seen in 7.6% comprising of 1.3% cervical intraepithelial neoplasia (CIN), 6.1% human papilloma virus (HPV) infection and 0.2% atypical squmous cells of undetermined significances (ASCUS). Yeast and other infections were found in 6.9% and 1.9% respectively. Comparatively, postmenopausal women had a 2.8 fold higher cancerous changes whereas premenopausal women had a higher infection rate, 11.8% vs. 4.7% respectively (p=0.024) with comparable HPV infection rates in both. This study found 1.3% had breast cancer (BC) with 3.6% requiring a biopsy while 3.4% needed regular follow up. Postmenopaused women had more abnormal mammograms (p
    Matched MeSH terms: Yeast, Dried
  4. Zentou H, Zainal Abidin Z, Yunus R, Awang Biak DR, Abdullah Issa M, Yahaya Pudza M
    ACS Omega, 2021 Feb 16;6(6):4137-4146.
    PMID: 33644536 DOI: 10.1021/acsomega.0c04025
    Despite the advantages of continuous fermentation whereby ethanol is selectively removed from the fermenting broth to reduce the end-product inhibition, this process can concentrate minor secondary products to the point where they become toxic to the yeast. This study aims to develop a new mathematical model do describe the inhibitory effect of byproducts on alcoholic fermentation including glycerol, lactic acid, acetic acid, and succinic acid, which were reported as major byproducts during batch alcoholic fermentation. The accumulation of these byproducts during the different stages of batch fermentation has been quantified. The yields of total byproducts, glycerol, acetic acid, and succinic acid per gram of glucose were 0.0442, 0.023, 0.0155, and 0.0054, respectively. It was found that the concentration of these byproducts linearly increases with the increase in glucose concentration in the range of 25-250 g/L. The results have also showed that byproduct concentration has a significant inhibitory effect on specific growth coefficient (μ) whereas no effect was observed on the half-velocity constant (Ks). A new mathematical model of alcoholic fermentation was developed considering the byproduct inhibitory effect, which showed a good performance and more accuracy compared to the classical Monod model.
    Matched MeSH terms: Yeast, Dried
  5. Ismail Fitry Mohammad Rashedi, Safiullah Jauhar, Chong, ?Gun Hean, Nor Khaizura Mahmud @ Ab Rashid, Wan Zunairah Wan Ibadullah
    MyJurnal
    Supercritical carbon dioxide (SC-CO2 ) is a non-thermal technique implemented by food, pharmaceutical, and similar industries with the aim of inhibiting the microorganisms and apply effective sterilisation. Presently, limited number of studies has reported the application of SC-CO2 on fresh chicken meat. The present work therefore aimed to reveal the microbial and physicochemical quality of the SC-CO2 -treated fresh chicken meat. The fresh chicken meat was subjected to the SC-CO2 at 14 MPa and 45°C for 40 min and was stored at 4°C for 0, 3, and 7 days. The obtained results indicated that the treatment with SC-CO2 significantly decreased the total plate count and, yeast and mould count from log10 5.90 to 2.00 CFU/g and from log10 5.02 to 2.00 CFU/g at day 7 of storage, respectively. The values of pH, cooking loss, and water holding capacity were not affected by the treatment. The results revealed that the SC-CO2 -treated samples displayed harder texture, higher lightness and yellowness, and lower redness. In addition, lipid peroxidation of SC-CO2 and control samples resulted in values of 1.9 and 0.5 MDA/mg of meat at day 7 of storage time and did not significantly change in the rest of the evaluation days. In summary, the application of SC-CO2 was capable of enhancing the microbial quality and certain physicochemical attributes. However, alteration of certain parameters of SC-CO2 might enhance the overall meat quality.
    Matched MeSH terms: Yeast, Dried
  6. Ng, S.H., Wan Rosli, W.l.
    MyJurnal
    The proximate compositions, total dietary fibre (TDF) content, textural properties and sensory acceptability of yeast breads formulated with 0%, 2%, 4% and 6% of cornsilk powder (CSP) were studied. The protein, ash and TDF contents of yeast breads were increased in line with the CSP level added whereas moisture content was decreased. Yeast bread added with 6% CSP recorded the highest content of TDF (5.91%), protein (9.76%) and ash (1.03%) compared to other formulation of yeast breads containing lower percentage of CSP. Besides, texture profile analysis (TPA) reported that the firmness, gumminess and chewiness of yeast breads increased directly proportional to the level of CSP added mainly due to higher content of TDF and lower content of moisture. However, for the yeast bread added with 2%CSP, there were no significant differences compared with control yeast bread. Among all cornsilk-based yeast bread, formulation containing 2% CSP had the highest scores for all attributes including overall acceptance and there were no significant differences with control yeast bread. The present study indicated that the addition of 2% CSP could be an effective way to produce functional yeast bread without changing negatively its desirable textural and sensory acceptability.
    Matched MeSH terms: Yeast, Dried
  7. Chia, S. L., Rosnah, S., Noranizan, M. A., Wan Ramli, W. D.
    MyJurnal
    The effect of storage time on the quality of ultraviolet-irradiated and thermally pasteurised pineapple juice was evaluated. The juices were irradiated with ultraviolet light (UV-C) at wavelength 254 nm (53.42 mJ/cm2, 4.918 s), thermally pasteurised at 800C for 10 minutes and stored at 40C for 13 weeks. There were significant changes in the total soluble solids, pH, titratable acidity and turbidity of UV-irradiated juice during storage, whereas for the same quality attributes of thermally pasteurised juice remained stable throughout the storage time. There were no significant changes in total phenolics for both treatments throughout the storage period. Other quality parameters (ascorbic acid, colour L, hue angle and chroma) were significantly affected by the storage time. Regarding the microbiological analysis, the total plate counts and yeast and mould counts of the UV-irradiated juice increased gradually throughout the 13 weeks of storage while these parameters remained unchanged in the thermally pasteurised juice with almost no microorganism growth. UV-irradiated pineapple juice preserved better quality attributes (TSS, pH, titratable acidity, ascorbic acid, turbidity, total phenolic, L (lightness), hue angle and chroma) than the thermal pasteurised juice during the storage time. Hence, UV irradiation has great potential as an alternative technology to thermal pasteurisation in producing products of high nutritive values.
    Matched MeSH terms: Yeast, Dried
  8. Suguna, M., Rajeev Bhat, Wan Nadiah, W. A.
    MyJurnal
    Microbiological qualities of fresh goat milk collected from two selected, popular dairy farms in Penang Island, Malaysia were evaluated, as a measure of food safety. Milk samples were screened for total plate counts, yeast and mould counts, psychrotrophic counts, Staphylococcus aureus, presumptive Escherichia coli, Coliforms and Klebsiella pneumoniae, which were in the range of (mean values) 4.2- 4.5, 4.2- 4.6, 3.1- 4.3, 2.7- 3.2, < 2- 4.6, 2.2- 4.0 and 4.1- 4.8 log CFU/ml, respectively in the two farms. Milk samples were also screened for the presence of selected foodborne pathogens such as Listeria monocytogenes and Salmonella sp. Results
    showed the presence of only Salmonella sp. (at 2.9 log CFU/ml) with the absence of Listeria monocytogenes. The outcome of this study assumes importance as the presence of microbial contaminants amounts indicates poor milk quality, which requires immediate consideration as it can pose serious health risk to consumers.
    Matched MeSH terms: Yeast, Dried
  9. Noroul Asyikeen, Z., Ma’aruf, A.G., Sahilah, A.M., Mohd. Khan, A., Wan Aida, W.M.
    MyJurnal
    Megabiodiversity of Malaysian’s flora and fauna which include microorganism could be conserved and served as alternative source indigenous yeast, the leavening agent of commercial bread making. This study was conducted in attempt to exploit the potential of Saccharomyces cerevisiae strains isolated from 30 different local fruits and plant parts as a leavening agent in bread making. The enrichment was carried out by fermenting the plant samples in medium containing Grape Must at 25°C for 10 days following by isolation of tentative yeasts at 30°C for 3 to 5 days. 20 out of 30 samples tested showed the presence of yeasts was then selected for identification of S. cerevisiae strains through biochemical and physiological tests. Of the 20 yeast strains examined, 13 strains were identified as S. cerevisiae and potentially used as leavening agent in bread making where 5 strains namely SN3, SMK9, SDB10, SRB11 and SS12 showed better fermentative performance compared to commercial strains. Thus, indicated that the local fruits and plant parts could be the potential source of indigenous S. cerevisiae strains for leavening agent in bread making.
    Matched MeSH terms: Yeast, Dried
  10. Ding, C.H., Tzar M.N., Biswas S., Muttaqillah N.A.S., Wahab A.A.
    MyJurnal
    Catheter-related bloodstream infections caused by Kodamaea ohmeri are generally not considered due to the relative scarcity of reported cases. This is a case of an 85-year-old man with poorly controlled diabetes mellitus who was initially admitted to our hospital for diabetic ketoacidosis. An internal jugular catheter was inserted as part of the initial management. A week later the patient developed a temperature spike and a yeast identified as Kodamaea ohmeri by ID 32 C (bioMérieux, France) was isolated from both his central and peripheral blood cultures. The catheter was removed and the patient was treated with fluconazole despite the organism’s relatively high minimum inhibitory concentration (2 μg/mL) to this antifungal. The fungemia resolved following a 2-weeks course of fluconazole.
    Matched MeSH terms: Yeast, Dried
  11. Ng TS, Mohd Desa MN, Sandai D, Chong PP, Than LT
    Jundishapur J Microbiol, 2015 Nov;8(11):e25177.
    PMID: 26855740 DOI: 10.5812/jjm.25177
    BACKGROUND: The sensing mechanism of glucose in Saccharomyces cerevisiae is well studied. However, such information is scarcely found in other yeast species such as Candida glabrata.

    OBJECTIVES: This study aimed to identify the glucose sensing pathway related genes of C. glabrata and to analyze the regulation pattern of these genes in response to different surrounding glucose concentrations through the quantitative real time polymerase chain reaction (qRT-PCR).

    MATERIALS AND METHODS: Phylogenetic analysis was carried out on predicted amino acid sequences of C. glabrata and S. cerevisiae to compare their degree of similarity. In addition, the growth of C. glabrata in response to different amounts of glucose (0%, 0.01%, 0.1%, 1% and 2%) was evaluated via the spot dilution assay on prepared agar medium. Besides, the SNF3 and RGT2, which act as putative glucose sensors, and the RGT1 and MIG1, which act as putative transcriptional regulators and selected downstream hexose transporters (HXTs), were analysed through qRT-PCR analysis for the gene expression level under different glucose concentrations.

    RESULTS: Comparative analysis of predicted amino acids in the phylogenetic tree showed high similarity between C. glabrata and S cerevisiae. Besides, C. glabrata demonstrated the capability to grow in glucose levels as low as 0.01% in the spot dilution assay. In qRT-PCR analysis, differential expressions were observed in selected genes when C. glabrata was subjected to different glucose concentrations.

    CONCLUSIONS: The constructed phylogenetic tree suggests the close evolutionary relationship between C. glabrata and S. cerevisiae. The capability of C. glabrata to grow in extremely low glucose environments and the differential expression of selected glucose-sensing related genes suggested the possible role of these genes in modulating the growth of C. glabrata in response to different glucose concentrations. This study helps deepen our understanding of the glucose sensing mechanism in C. glabrata and serves to provide fundamental data that may assist in unveiling this mechanism as a potential drug target.

    Matched MeSH terms: Yeast, Dried
  12. Mat Nanyan NSB, Takagi H
    Front Genet, 2020;11:438.
    PMID: 32411186 DOI: 10.3389/fgene.2020.00438
    Overexpression of MSN2, which is the transcription factor gene in response to stress, is well-known to increase the tolerance of the yeast Saccharomyces cerevisiae cells to a wide variety of environmental stresses. Recent studies have found that the Msn2 is a feasible potential mediator of proline homeostasis in yeast. This result is based on the finding that overexpression of the MSN2 gene exacerbates the cytotoxicity of yeast to various amino acid analogs whose uptake is increased by the active amino acid permeases localized on the plasma membrane as a result of a dysfunctional deubiquitination process. Increased understanding of the cellular responses induced by the Msn2-mediated proline incorporation will provide better comprehension of how cells respond to and counteract to different kinds of stimuli and will also contribute to the breeding of industrial yeast strains with increased productivity.
    Matched MeSH terms: Yeast, Dried
  13. Chin IBI, Yenn TW, Ring LC, Lazim Y, Tan WN, Rashid SA, et al.
    J Pharm Sci, 2020 09;109(9):2884-2890.
    PMID: 32534882 DOI: 10.1016/j.xphs.2020.06.005
    Pressure ulcers are commonly associated with microbial infections on the wounds which require an effective wound dressing for treatment. Thus far, the available silver dressing has shown tremendous result, however, it may cause argyria and complicate the internal organ function. Hence, our study aims to develop and characterize phomopsidione-loaded chitosan-polyethylene glycol nanocomposite hydrogel (C/PEG/Ph) as an antimicrobial dressing. Physically, the C/PEG/Ph hydrogel demonstrated a uniform light blue color, soft, flexible, and elastic, with no aggregation form. The evaluation via Fourier Transform Infrared (FTIR) exposed the C/PEG/Ph hydrogel has a notable shift towards lower frequency at 1600 and 1554 cm-1. For drug release test, the phomopsidione attained plateau at 24 h, with a total release of 67.9 ± 6.4% from the C/PEG/Ph hydrogel. There was a null burst release effect discovered throughout the experimental period. The C/PEG/Ph hydrogel showed significant results against all 4 Gram-negative bacteria and 1 yeast, with 99.99-100% reduction of microbial growth. The findings revealed that the C/PEG/Ph hydrogel can potentially act as an antimicrobial dressing for pressure ulcers.
    Matched MeSH terms: Yeast, Dried
  14. Ikram NK, Zhan X, Pan XW, King BC, Simonsen HT
    Front Plant Sci, 2015;6:129.
    PMID: 25852702 DOI: 10.3389/fpls.2015.00129
    Plants biosynthesize a great diversity of biologically active small molecules of interest for fragrances, flavors, and pharmaceuticals. Among specialized metabolites, terpenoids represent the greatest molecular diversity. Many terpenoids are very complex, and total chemical synthesis often requires many steps and difficult chemical reactions, resulting in a low final yield or incorrect stereochemistry. Several drug candidates with terpene skeletons are difficult to obtain by chemical synthesis due to their large number of chiral centers. Thus, biological production remains the preferred method for industrial production for many of these compounds. However, because these chemicals are often found in low abundance in the native plant, or are produced in plants which are difficult to cultivate, there is great interest in engineering increased production or expression of the biosynthetic pathways in heterologous hosts. Although there are many examples of successful engineering of microbes such as yeast or bacteria to produce these compounds, this often requires extensive changes to the host organism's metabolism. Optimization of plant gene expression, post-translational protein modifications, subcellular localization, and other factors often present challenges. To address the future demand for natural products used as drugs, new platforms are being established that are better suited for heterologous production of plant metabolites. Specifically, direct metabolic engineering of plants can provide effective heterologous expression for production of valuable plant-derived natural products. In this review, our primary focus is on small terpenoids and we discuss the benefits of plant expression platforms and provide several successful examples of stable production of small terpenoids in plants.
    Matched MeSH terms: Yeast, Dried
  15. Noorhisham Tan Kofli, Nagahisa K, Shioya S, Shimizu H
    Sains Malaysiana, 2006;35:9-15.
    During fermentation cells are subjected to various kinds of stress. One of the stresses concerned is high osmotic environment, which cells need to encounter in order to continue growing. To understand how cells adapt to this stress condition, information from genome, proteome and metabolome levels are crucial. In yeast cells, it was report that they produce glycerol to avoid depletion of water in the cell that could lead to cell shrinkage and eventually death. Thus, investigation of physiological responses were executed by shake flask method using three different Saccharomyces cerevisiae strains namely s288c, IFO2347 and FY834 which were grown in yeast potato dextrose (YPD) medium under the treatment of sodium chloride (NaCl) and sorbitol at 1M concentration to create the osmotic condition. These agents were added into the medium after 5 hours of fermentation when the cells reached exponential phase and carbon source is still available. The results proved that addition of both NaCl and sorbitol created the osmotic condition during growth resulted in higher accumulation of glycerol and trehalose when compared to the control in all strains. Among these strains, production of glycerol (g glycerol/g cell dry weight) was found highest in IFO2347, followed by s288c and FY834.
    Matched MeSH terms: Yeast, Dried
  16. Ismail, I., Anuar, M.S., Shamsudin, R.
    MyJurnal
    Green coffee beans are stored for a certain period and under certain conditions until they are finally utilized. The storage period may depend on customer demand while the storage conditions depend on where the coffee beans are stored. Thus, this research emphasizes the physicochemical changes that occur in Liberica coffee beans during storage under the Malaysian
    climate (average temperature and relative humidity of 29.33ºC and 71.75% respectively). The changes in the physico-chemical (coffee size, mass, densities, colour, proximate analysis, sucrose, chlorogenic acid content) and microbiological (yeast and mould count) properties were evaluated during eight months of storage. After the storage, the physical properties of the coffee changed as the coffee beans expanded in size, reduced in mass and density and became brighter in colour. Changes in the chemical properties were also detected where the moisture decreased and the ash content increased. In addition, the sucrose level was found to decrease with a corresponding increase in chlorogenic acid. During storage, the counts of yeast and mould were reduced. Model equations describing the changes in the properties were developed. The overall conclusion was that the coffee beans reduced in quality during storage.
    Matched MeSH terms: Yeast, Dried
  17. Rashed, K., Said, A., Abdo, A., Selim, S.
    MyJurnal
    This work was carried out for determining antimicrobial activity of Pistacia chinensis leaves
    methanol extract and identifying the chemical composition of the plant extract. Methanol extract
    was tested for antimicrobial activity using disc-diffusion assay and the extract was fractionated
    on silica gel column chromatography for the isolation of the bio-active constituents. The leaves
    extract of P. chinensis showed a significant antimicrobial effect, it strongly inhibited the growth
    of the test bacteria and yeast studied. Chromatograpic separation of the methanol extract of
    P. chinensis leaves has led to the isolation and characterization of β-sitosterol, luepol, and
    six flavonoids, quercetin, myricetin, quercetin 3-O-α-rhamnoside, quercetin 3-O-β-glucoside,
    myricetin 3-O-α-rhamnoside and myricetin 3-O-β-glucuronide using various chromatographic
    procedures and the interpretation of spectral data in comparison with already existing data
    reported in the literature. The results presented here may suggest that the leaves extract of P.
    chinensis possess antimicrobial properties, and therefore, can be used as natural preservative
    ingredients in food and/or pharmaceuticals.
    Matched MeSH terms: Yeast, Dried
  18. Koh, S.P., Aziz, N., Sharifudin, S.A., Abdullah, R., Hamid, N.S.A., Sarip, J.
    Food Research, 2017;1(4):109-113.
    MyJurnal
    Foodborne illness is recognized as an emerging infectious disease. The incidence of foodborne
    infections is common and the majority cases are undiagnosed or unreported. Apart from some
    diarrhea or minor gastrointestinal problem, some foodborne pathogenic microbes may cause
    death, particularly to those people with weakened immune system. In this study, we have
    developed a new fermented papaya beverage using symbiotic culture of yeast and acetic acid
    bacteria under controlled biofermentation process. An in-vitro assessment of fermented papaya
    beverage against few foodborne pathogenic microorganism was conducted to determine
    its minimum bactericidal concentration (MBC>99). Three types of foodborne pathogen:
    Escherichia coli O157, Salmonella enterica serovar Typhimurium ATCC 53648, Salmonella
    enterica serovar Enteritidis (isolated from infectious chicken) were selected. From minimum
    bactericidal concentration (MBC>99) assay, both fermented papaya pulp and leaves beverages
    have shown 100% killing rate against three selected foodborne pathogenic microbes. Inversely,
    non-fermented papaya pulp and leaves beverages indicated no inhibition at all. In fact, further
    dilution of fermented papaya pulp and leaves beverages demonstrated different degree of
    MBC>99 and brix value, but the pH value remained less than 3.5. These findings indicated
    the combination of soluble solid compounds presents in both fermented papaya beverage and
    product acidity play an important role in the inhibition of pathogenic microorganisms. The
    preliminary promising results of this work have shown that the great potential of fermented
    papaya beverages as a preventive measure to reduce the incidence of foodborne illness.
    Matched MeSH terms: Yeast, Dried
  19. Masri SN, Noor SM, Nor LA, Osman M, Rahman MM
    Pak J Med Sci, 2015;31(3):658-61.
    PMID: 26150863 DOI: 10.12669/pjms.313.7072
    Pregnant women are susceptible to vaginal colonization and infection by yeast. The purpose of the study was to determine the prevalence of Candida spp in high vaginal swabs of pregnant women and their antifungal susceptibility.
    Matched MeSH terms: Yeast, Dried
  20. Mukhtar H, Suliman SM, Shabbir A, Mumtaz MW, Rashid U, Rahimuddin SA
    Protein Pept Lett, 2018;25(2):195-201.
    PMID: 29359654 DOI: 10.2174/0929866525666180122112805
    BACKGROUND: Lipid-producing microorganisms, said to be oleaginous have been recognized since several years. We had investigated the effects of medium components and culturing situations on cell growth and lipid accumulation of oleaginous yeasts which were analytically examined so as to enhance lipid yield for biodiesel production.

    OBJECTIVE: The main objective of this study was to explore oleaginous yeast, Yarrowia lipolytica isolated from soil and optimization of culture conditions and medium components to obtained better quality microbial oil for biodiesel production.

    METHODS: Fifty yeast strains were isolated from soil from different regions of Lahore and eleven of them were selected for oil production. The isolated yeast colonies were screened to further check their lipid producing capabilities by the qualitative analysis. Five yeast strains were designated as oleaginous because they produced more than 16% of oil based on their biomass. To estimate the total lipid content of yeast cells, the extraction of lipids was done by performing the procedure proposed by Bligh and Dyer. The transesterification of yeast oils was performed by using different methods. There were three different strategies customized to transesterifying microbial oil using base catalyzed transesterification, acid catalyzed transesterification and enzyme-based transesterification. After completion of transesterification, sample was used for fatty acid methyl esters (FAMEs) were analyzed by gas-chromatograph with ionization detector type MS.

    RESULTS: The isolate IIB-10 identified as Yarrowia lipolytica produced maximum amount of lipids i.e. 22.8%. More amount of biomass was obtained when cane molasses was utilized as carbon source where it produced 29.4 g/L of biomass while sucrose and lactose were not utilized by IIB-10 and no biomass was obtained. Similarly, meat extracts showed best results when it was used as nitrogen source because it resulted in 35.8 g/L biomass of Yarrowia lipolytica IIB-10. The culturing conditions like size of inoculum, effect of pH and time of incubation were also studied. The 10% of inoculum size produced 25.4 g/L biomass at 120 h incubation time, while the pH 7 was the optimum pH at which 24.8 g/L biomass was produced by Yarrowia lipolytica IIB-10. GC-MS analysis showed that biodiesel produced by transesterification contained similar fatty acids as found in vegetable oil for this reason it is widely accepted feedstock for biodiesel production.

    CONCLUSION: The analysis of fatty acids methyl esters showed the similar composition of microbial oil as in vegetable oils and high amount of methyl esters were obtained after transesterification. Therefore, potentially oleaginous yeast could be used to generate a large amount of lipids for biodiesel production that will be the better substitute of petroleum-based diesel and will also control the environmental pollution.

    Matched MeSH terms: Yeast, Dried
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