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"Biosensor untuk penentuan BOD secara amperometrik telah dikembangkan dengan menggabungkan elektroda pengukur oksigen terlarut dengan khamir Rhodotorula mucilaginosa UICC Y - 181 terimobilisasi. Sensor dibuat dari elektroda emas yang dilapisi membran nafion 50 mikron dan biofilm gelatin yang mengandung khamir Rhodotorula mucilaginosa UICC Y - 181 terimobilisasi. Hubungan linear antara respon sensor dan konsentrasi glukosa sebagai larutan standar BOD dalam bufer fosfat pH 7, terlihat dalam rentang antara 10 sampai 70 mg/L, dengan nilai BOD berdasarkan larutan standar glukosa dengan nilai R2= 0,98. Namun respon ini masih lebih rendah dibandingkan dengan pengukuran menggunakan free cell Rhodotorula mucilaginosa UICC Y - 181 yang menghasilkan respon pada rentang 10 sampai 90 mg/L BOD dengan R2= 0,96. Penentuan BOD membutuhkan waktu minimal 5 menit.

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Biosensor for amperometric determination of Biochemical Oxygen Demand (BOD) was developed using combination of electrode for oxygen sensor and immobilized Rhodotorula mucilaginosa UICC Y - 181. This sensor made from gold electrode installed with a 50 micron nafion membrane and a gelatin biofilm containing immobilized yeast, Rhodotorula mucilaginosa UICC Y - 181. A linear relationship between the sensor response and the concentration of glucose as standar solution for BOD in phosphate buffer of pH 7, was observed in range 10 to 70 mg/L BOD standard glucose solution with R2= 0,98. This response was still low in comparing to the free cell yeast that show better response in the range 10 to 90 mg/L BOD standard glucose solution with R2= 0,96. The minimal measuring time for BOD determination was 5 minute."

"Pengaruh ion Cu2+ diuji untuk sensor BOD yang sedang dikembangkan. Sensor BOD dibuat dengan menggunakan sistem sel khamir bebas untuk khamir Rhodotorula mucilaginosa UICC Y-181 dan khamir Candida fukuyamaensis UICC Y-247 pada elektroda emas. Penentuan nilai reduksi oksigen pada -600 mV (vs Ag/AgCl) ditentukan dengan cyclic voltametri. Sedangkan deteksi oksigen sisa yang tidak digunakan oleh mikroorganisme dilakukan dengan teknik multi pulse amperometry (MPA). Hasil pengukuran kalibrasi linier pada keadaan free cell untuk kedua jenis khamir menunjukkan nilai daerah kelinieran yang baik dengan nilai regresi 0,994 dan 0,987 berturut-turut untuk keadaan free cell Rhodotorula mucilaginosa UICC Y-181 dengan waktu optimum pengukuran 20 menit dan untuk keadaan free cell Candida fukuyamaensis UICC Y-247 dengan waktu optimum pengukuran 25 menit. Presisi yang lebih baik ditunjukkan dengan 15 kali pengukuran untuk khamir Rhodotorula mucilaginosa dengan nilai RSD 0,9 %, sedangkan untuk khamir Candida fukuyamaensis dengan nilai RSD 5,01%. Pengaruh keberadaan logam berat pada sistem pengukuran dilakukan dengan menvariasikan konsentrasi ion Cu2+. Sensor BOD dengan Rhodotorula mucilaginosa menunjukkan ketahanan yang lebih baik terhadap kehadiran ion Cu2+ seperti ditunjukkan oleh sedikitnya kenaikan arus oksigen dibandingkan dengan kenaikan arus oksigen pada sensor BOD dengan Candida fukuyamaensis.

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Influence of copper ions was examined on developed microbial BOD sensors.The BOD sensors carried out in a system consisted of free cell yeast and gold electrode. Rhodotorula mucilaginosa UICC Y-181 and Candida fukuyamaensis UICC Y-247 were used as the microbial yeasts. Oxygen reduction potensial of -600 mV (vs Ag/AgCl) was determined by using cyclic voltametry, whereas the excess oxygen concentration, which not used by microorganism, was determined by multy pulse amperometry (MPA). Optimum waiting times of 20 and 25 min were obtained for BOD sensors of Rhodotorula mucilaginosa UICC Y-181 and Candida fukuyamaensis UICC Y-247, respectively. Linear calibration curves showed good linearity with linear regressions of 0.994 and 0.987 for those of Rhodotorula mucilaginosa UICC Y-181 and Candida fukuyamaensis UICC Y-247, respectively. However, better precision of measurement (n=15) was shown by an RSD of 0.90% for Rhodotorula mucilaginosa, whereas it was 5.01% for Candida fukuyamaensis. Influence of copper ions was examined in various concentrations of Cu ions. BOD sensor of Rhodotorula mucilaginosa shows better resistance against Cu ions than that of Candida fukuyamaensis, as it is shown by less increasing of oxygen current at Rhodotorula mucilaginosa than that at Candida fukuyamaensis."

"Elektroda AuNp-BDD dan Au-BDD dikembangkan sebagai elektroda kerja untuk pengukuran biochemical oxygen demand (BOD) menggunakan Rhodotorula mucilaginosa UICC Y-181 terimobilisasi pada Na-alginat. Pengukuran BOD dilakukan dengan mengamati perubahan konsentrasi oksigen akibat proses oksidasi senyawa organik dalam larutan oleh mikroorganisme. Glukosa dan galaktosa digunakan sebagai model senyawa organik. Teknik multi pulse amperometry pada potensial reduksi oksigen -670 mV vs Ag/AgCl digunakan untuk mendeteksi oksigen sisa yang tidak digunakan oleh mikroorganisme. Waktu tunggu optimum adalah 10 menit dan ketebalan lapisan imobilisasi adalah 2 mm. Karakterisasi elektroda dengan XPS menunjukkan rasio Au/C untuk Au-BDD dan AuNp-BDD adalah 0.0553 dan 0.2084. Pada pengukuran oksigen, elektroda AuNp-BDD ditemukan lebih sensitif dibandingkan elektroda Au-BDD maupun elektroda Au. Sedangkan sensor BOD dengan mikroorganisme terimobilisasi ditemukan memiliki waktu pengukuran lebih cepat, sensitifitas lebih tinggi, repeatbility lebih baik dan limit deteksi lebih rendah dibandingkan sensor dengan mikroorganisme bebas. Kelinieran yang baik (R2 = 0.994) ditunjukkan untuk glukosa pada retang konsentrasi 0.1 ? 0.9 mM (ekuivalen dengan 10 - 90 mg/L BOD) dan limit deteksi 0.46 mg/L BOD. Kestabilan arus yang baik ditunjukkan oleh nilai RSD 3.35% (n=8 pengukuran). Laju konsumsi oksigen dengan sumber karbon glukosa lebih tinggi dari galaktosa menandakan bahwa khamir Rhodotorula mucilaginosa lebih mudah mendegradasi glukosa. Keberadaan ion Cu2+ memberikan pengaruh pada sel khamir Rhodotorula mucilaginosa dengan penurunan konsumsi oksigen.

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NanoGold-modified boron doped diamond (AuNp-BDD) and Golddeposited boron doped diamond (Au-BDD) electrodes were used as working electrodes for measuring biochemical oxygen demand (BOD) using Rhodotorula mucilaginosa UICC Y-181 immobilized in a Na-alginate matrix. BOD measurement is done by observing the changes in oxygen concentration due to oxidation of organic compounds in solution by microorganisms. Glucose and galactose were used as model organic compounds. Multy-pulse amperometry technic at -0.67 V (vs Ag/AgCl) of oxygen reduction potensial was used to detect the remaining of oxygen which is not used by microorganisms. An optimum waiting time was observed to be 10 min and thickness of immobilization matrix is 2 mm. Ratio of Au/C 0.0553 and 0.2084 was obtained by XPS for Au-BDD and AuNp-BDD electrodes, respectively. Dissolved oxygen detection, AuNp-BDD electrode is more sensitive than Au-BDD or Au electrodes. The BOD sensor using immobilized microorganism was found to have a faster measurement time, higher sensitivity, better repeatbility and lower detection limit compared to the sensor using free microorganisms. Good linierity (R2 = 0.994) was shown in the range of glucose concentration of 0.1 - 0.9 mM (equivalent to 10 ? 90 mg/L BOD) and detection limit of 0.46 mg/L BOD. Good stability of currents were shown by an RSD of 3.35%(n=8). The rate of oxygen consumption to glucose is higher than of galactose, indicating that glucose is a better substrate for Rhodotorula mucilaginosa than that of galactose. The presence of Cu ions influence the yeast cells with a decreasing in oxygen consumption."

"Pengembangan sensor BOD (Biochemical Oksigen Demand) dilakukan menggunakan biosensing khamir Rhodotorula mucilaginosa UICC Y-181 yang terimobilisasi dalam matriks gelatin dan alginat. BOD diukur sebagai jumlah oksigen yang digunakan oleh biosensing dalam selang waktu tertentu untuk mengoksidasi senyawa organik dalam larutan. Pada penelitian ini glukosa digunakan sebagai model senyawa organik. Kadar oksigen dalam larutan diukur menggunakan elektroda emas dan elektoda Boron-Doped Diamond termodifikasi nanopartikel emas sebagai elektroda kerja dengan teknik Multi Pulse Amperometry melalui reaksi reduksi oksigen pada -554 mV (vs Ag/AgCl). Kurva kalibrasi linear diperoleh dari perubahan arus reduksi oksigen setelah selang waktu tunggu optimum 20 menit (ΔI = I0 ?I20) pada larutan glukosa dalam berbagai variasi konsentrasi (0,1 ? 0,9 mM) setelah larutan dijenuhkan dengan oksigen. Selain mikroorganisme terimobilisasi, mikroorganisme dalam keadaan bebas (free cell) juga digunakan sebagai pembanding. Regresi linier (R2 = 0,95 - 0,99) dapat diperoleh pada semua sensor BOD baik dengan mikroorganisme bebas maupun terimobilisasi. Tetapi sensitivitas sensor dengan mikroorganisme bebas umumnya lebih tinggi daripada keadaan terimobilisasi, walaupun kedapatulangan yang lebih baik umumnya diperoleh pada sensor dengan mikroorganisme terimobilisasi, terutama yang terimobilisasi dalam matriks gelatin.

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The development of BOD sensor was conducted by using Rhodotorula mucilaginosa UICC Y-181 yeast imobilized in gelatine and alginate matrix as the biosensing agent. BOD was measured as oxygen amount used by the biosensing agent to oxidize organic compounds in solution. In this work, glucose was used as an organic compound model. Oxygen concentration in water was measured by using gold and gold nanoparticles-modified Boron-Doped Diamond electrodes with Multy Pulse Amperometry technique via oxygen reduction reaction at -554 mV (vs Ag/AgCl).

Linear calibration curves was performed at change of oxygen reduction current after an optimum waiting time of 20 min ΔI (I0 ?I20) to solutions with a various glucose concentrations (0.1 - 0.9 mM) after saturated by oxygen. Beside the use of immobilized microorganism, free cell of the microorganism was also used as a comparison. The linear regression (R2 = 0.95 ? 0.99) could be observed at all BOD sensors with the free and the immobilized cells. However, the sensitivity of the sensors with free cell were generally higher than that of the immobilized ones, although better reproducibility was shown at the sensors with immobilized microorganisms, especially which were immobilized in gelatine matrix."

"ABSTRACTBiological control of postharvest diseases of fruits and vegetables byantagonistic microorganism seems increasingly promising to replace the use of synthetic fungicides which are subjected to some limitation due to development of fungicides-resistant strain of the pathogens and risk for consumers and the environment (Lima et al, 1999). Several species of yeast have been reported to reduce postharvest fungal decay on fruits. One of the antagonistic yeast that has been use as commercial biocontrol is Metchnikowia fructicola in Shemerm product (Vero et al., 2002) Yeast Rhodotomla has been studied for the postharvest biologicalcontrol various mould pathogens on various fruit (Castoria et al., 1997).University of Indonesia Culture Collection (UICC) have Rhodotorula spp.strains from plants of Cibodas Botanical Garden, and moulds frompostharvest decayed-tomatoes and plants. The ability of these yeast strains as biocontrol agents against has not been reported.This thesis consists of two parts. Part 1 is entitled The antagonisticActivity of Rhodotorula spp. from Cibodas Botanical Garden Against Tomato Plant Infected-Causing Moulds. Part 2 is entitled The Potential of Rhodotorula sp. UICC Y-381 as Biocontrol Agent of Aspergillus ochraoeus on Postharvest Tomatoes. The objectives of this research are to obtain a potential Rhodotorula sp. with antagonistic activity against tomato infected-causing moulds, and to obtain infoimation on the ability of Rhodotorula sp. UICC Y- 381 as a biocontrol agent in reducing the severity of decay by Aspergillus ochraceus. The research was carried out in Laboratory of Microbiology, Department of Biology, and Center of Excellence Indigenous Biological Resources-Genome Studies (CoE IBR-GS), Faculty of Mathematics and Natural Sciences, from July 2008-July 2009.Yeast Malt Agar (YMA) was used for yeast growth medium, and PotatoDextrose Agar (PDA) was used for maintenance of fungi. The media PDA and Potato Dextrose Agar (PDB) were used for antagonistic test.Six strains of Rhodotorula spp. (Rhodotorula sp. UICC Y-318,Rhodotorula sp. UICC Y-325, Rhodotorula sp. UICC Y-332, Rhodotorula sp. UICC Y-381, Rhodotomla sp. UICC Y-384, and Rhodotorula sp. UICC Y-386) were investigated as antagonistic yeasts against Aspergillus ochraceus D1.2.2.SSM3, A. terreus D2.2.MC, and Drechslera sp. D1.3.MC. The yeasts were obtained from plants of Cibodas Botanical Garden, and the moulds were obtained from decayed tomatoes and infected plants, belonging to the University of Indonesia Culture Collection (UICC). Antagonistic test by strip method was carried out by usingconcentration of yeast cells at (1 .2-5.2) x 10° CFU/ml, and A. ochraceusD1.2.2.SSM3 at 4.7 x 10? CFU/ml, A. terreus D2.2.Mc at 3.2 x 10° CFU/ml,and Drechslera sp. D1.3.MC at 5.2 x 10? CFU/ml. Inoculation of the yeastcells on PDA was carried out 4 hours earlier before inoculation of mouldspores on petri dishes. Results showed that highest percentage reduction of mould colonies was shown by Rhodotorula sp. UICC Y- 325 againstDrechslera sp. (28.12%-72.14%), followed by Rhodotorufa sp. UlCC Y-381 against A. ochraoeus (54.28%-72.46%), and Rhodotoruta sp. Y-318 against A. terreus (21.76% - 58.10%) during 6-day incubation.Antagonistic test by co-culture method was carried out by usingconcentration of yeast cells at (1 .58-5.59) x 10° CFU/ml, and Aspergillus ochraceus D1.2.2.SSM3 at 7 x 10? cFU/ml, A. terreus D2.2.MC at 1.5 x 10? CFU/ml. Inoculation of the yeast cells on PDB was carried out 8 hours earlier before inoculation of mould spores on broth medium. Results showed that highest percentage reduction of conidial heads and hyphal width was shown by Rhodotorula sp. UICC Y-381 against A. ochraceus (9.45% and 12.43%; 7.10% and 7.51 %, after 2- and 3-day incubation, respectively). Rhodotorula sp. UICC Y-332 reduced conidial heads of A. terreus (10.17% and 9.60% after 2- and 3-day incubation) but, was not able to reduce hyphal width of A. terreus. Microscopic observation by slide culture method on PDA showed that there was attachment of Rhodotorula spp. cells to the hyphae of Drechslera sp., however, Rhodotorula spp. UICC Y-386 attached more intensively and colonized the hyphae.The ability of Rhodotorula sp. UICC Y-381, which was isolated fromplant leaves, as a biocontrol agent against postharvest tomato fruit decay- causing mould Aspergillus ochraceus D1 .2.2.SSM3 was evaluated. Observation was carried out for 15 days at 25°C - 27°C. Results showed that Rhodotorula sp. UICC Y-381 was able to reduce the severity of decay by A.ochraceus with 100% reduction until day-12, when compared to control. The synthetic fungicide Dithane M-45 at a concentration of 0.08% reduced the severity of decay to 100% until 15-day incubation."

"Elekroda Boron-Doped Diamond BDD termodifikasi nanopartikel tembaga-emas CuAuNP berhasil dipreparasi dengan metode perendaman setelah dilakukan pre-treatment dengan terminasi N. Coreshell nanopartikel tembaga emas CuAuNP disintesis dengan metode one pot chemical reduction sehingga terbentuk nanopartikel bimetalik yang stabil. Konfirmasi menggunakan spektrofotometer SEM-EDS menunjukan adanya interaksi dan keberadaan Cu dan Au pada permukaan BDD. Elektroda ini kemudian diaplikasikan sebagai sensor Biochemical Oxygen Demand BOD dengan mengukur jumlah oksigen yang dibutuhkan oleh mikroorganisme Rhodoturula mucilaginosa UICC Y-181 dalam larutan untuk mengoksidasi senyawa organik. Pada penelitian ini digunakan glukosa sebagai model senyawa organik. Kadar oksigen sisa dalam larutan diukur dengan teknik Multi Pulse Amperometry melalui reaksi reduksi oksigen pada -500mV vs Ag/AgCl . Kurva linieritas diperoleh dari selisih arus reduksi oksigen sebelum dan setelah waktu kontak 20 menit mikroorganisme dengan larutan glukosa ?I= I0-I20 . Larutan glukosa yang digunakan divariasikan dengan rentang konsentrasi 0,1 ndash; 0,5 mM. hasil pengukuran menunjukan bahwa BDDN-CuAuNP memiliko sensitivitas dan stabilitas yang lebih baik dibandingkan dengan elektroda BDDN-CuAuNP, mengindikasikan kontribusi Cu dalam BDDN-CuAuNP yang digunakan sebagai elektroda dalam biosensor BOD.

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Boron Doped Diamond BDD modified copper gold doped diamond CuAuNP was successfully prepared by immersion method after pre treated to be N termination. The gold copper coreshell nanoparticles CuAuNP were synthesized by the one pot chemical reduction method to form stable bimetallic nanoparticles. Confirmation using SEM EDS showing the presence of Cu and Au at the surface of BDD. This electrode was then applied for a Biochemical Oxygen Demand BOD sensor by measuring the amount of oxygen required by Rhodicurula Mucilaginosa UICC Y 181 microorganisms to oxidize the organic compounds.

In this study, glucose was used as the model of organic compounds. The residual oxygen content in the solution was measured by Multi Pulse Amperometry technique through oxygen reduction at 500 mV vs Ag AgCl . The linear calibration curve was obtained from the oxygen reduction currents before and after the contact time interval of 20 minutes I I0 I20 in a solution of glucose with saturated oxygen. The glucose concentration was varied from 0,1 to 0,5 mM. The measurements showed that BDDN CuAuNP electrodes has better sensitivity and stability than BDDN AuNP electrodes, indicated the contribution of Cu in BDDN CuAuNP, applied the BOD biosensors."

"Elekroda Boron-Doped Diamond BDD termodifikasi nanopartikel emas AuNP telah berhasil dipreparasi dengan metode perendaman. Sintesis AuNP dilakukan menggunakan capping agent alil amina dan poli alil amina dan menghasilkan AuNP dengan ukuran partikel rata-rata 93.197 39.228 nm. Karakterisasi BDD termodifikasi AuNP menggunakan XPS dan spektrofotometer SEM-EDS menunjukan adanya keberadaan Au pada permukaan BDD. Namun karakterisasi dengan cyclic voltammetry untuk BDD-AuNP hanya mendeteksi adanya puncak oksidasi dan reduksi Au pada BDD-AuNP dengan dengan capping agent alil amina, dan tidak mendeteksi kedua puncak tersebut pada BDD-AuNP dengan capping agent poli alil amina. BDD-AuNP hasil preparasi kemudian diaplikasikan sebagai sensor oksigen dan sensor Biochemical Oxygen Demand BOD dengan mengukur jumlah oksigen yang dibutuhkan oleh mikroorganisme Rhodoturula mucilaginosa UICC Y-181 dalam larutan untuk mengoksidasi senyawa organik. Glukosa digunakan sebagai sebagai model senyawa organik. Kadar oksigen sisa dalam larutan diukur dengan teknik Multi Pulse Amperometry melalui reaksi reduksi oksigen pada -500mV vs Ag/AgCl. Kurva kalibrasi linier diperoleh dari selisih arus reduksi oksigen sebelum dan setelah waktu kontak 20 menit mikroorganisme dengan larutan glukosa - ?I= I0-I20. Larutan glukosa yang digunakan divariasikan dengan rentang konsentrasi 0,1 ndash; 0,5 mM. Hasil pengukuran menunjukan bahwa BDDN-AuNP yang dipreparasi memiliki sensitifitas dan stabilitas yang baik digunakan sebagai elektroda dalam biosensor BOD.

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Boron Doped Diamond BDD modified gold nanoparticles AuNP electrode were successfully prepared by immersion method. The synthesis performed by using allylamine and poly allylamine as the capping agent produced AuNP with an average particle size of 93.197 39.228 nm. Characterization of AuNP modified BDD using XPS and SEM EDS spectrophotometers indicates the presence of Au on BDD surfaces. However, characterization with cyclic voltammetry observed the oxidation reduction couple peaks only at BDD AuNP with allylamine as the capping agent. On the contrary, the peaks were not observed at BDD AuNP with poly allylamine as the capping agent. Then, BDD AuNP electrode was applied as oxygen sensor and biochemical oxygen demand BOD sensors by measuring the amount of oxygen required by the Rhodoturula mucilaginosa UICC Y 181 to oxidize the organic compound in solution. Glucose has been used as a model of organic compounds. The residual oxygen content in solution was measured by Multy Pulse Amperometry technique through oxygen reduction reaction at 500mV vs Ag AgCl. The calibration curve with a concentration range of 0.1 0.5 mM glucose was obtained from the difference of the oxygen reduction current before and after 20 min contact time of microorganism with glucose solution I I0 I20. The measurement results show that the prepared BDD AuNP electrode has good sensitivity and stability for application in BOD biosensor. "

"Asam oleat merupakan asam lemak tak jenuh rantai panjang yang tergolong MUFA (Mono Unsaturated Fatty Acid). MUFA memiliki sifat yang lebih stabil dan memiliki peran yang lebih baik dibandingkan PUFA (Poly Unsaturated Fatty Acid) dalam menurunkan faktor risiko sindrom metabolik. Sindrom metabolik adalah kumpulan faktor risiko metabolik yang berhubungan langsung dengan penyakit kardiovaskular. Prevalensi sindrom metabolik diperkirakan akan terus meningkat. Dalam penelitian ini, ragi Rhodotorula glutinis, yang diklasifikasikan sebagai mikroorganisme berminyak, digunakan dengan asam oleat sebagai komposisi produk terbesar. Metode fermentasi terendam digunakan dengan media Yeast Malt Broth, pH 4, kecepatan pengadukan 120 rpm, dan suhu media budidaya sebagai variabel bebas. Selain itu, pengaruh strategi budidaya pergeseran suhu pada pertumbuhan ragi dan pembentukan asam lemak juga diperiksa. Strategi pergeseran suhu dilakukan dengan menumbuhkan ragi pada suhu optimal untuk pertumbuhan biomassa. Kemudian, suhu kultivasi diturunkan saat ragi memasuki fase diam. Metode ekstraksi yang digunakan adalah sonikasi menggunakan pelarut kloroform dan metanol berdasarkan metode Bligh and Dyer untuk mencapai hasil ekstraksi yang optimal dalam waktu singkat. Hasil penelitian menunjukkan bahwa suhu optimum untuk pertumbuhan Rhodotorula glutinis adalah 31oC dan untuk pembentukan asam oleat adalah 25oC. Pada penelitian ini, strategi pergeseran suhu dapat meningkatkan biomassa dari 11,06 g/L menjadi 11,94 g/L dan meningkatkan produksi lipid dari 3,24 g/L menjadi 4,58 g/L namun menurunkan kadar asam oleat dari 47,77% menjadi 43 %. Oleic acid is a long-chain unsaturated fatty acid belonging to MUFA (Mono Unsaturated Fatty Acid). MUFA has more stable properties and has a better role than PUFA (Poly Unsaturated Fatty Acid) in reducing risk factors for metabolic syndrome. Metabolic syndrome is a collection of metabolic risk factors that are directly related to cardiovascular disease. The prevalence of metabolic syndrome is expected to continue to increase. In this study, the yeast Rhodotorula glutinis, which is classified as an oily microorganism, was used with oleic acid as the largest product composition. Submerged fermentation method was used with Yeast Malt Broth media, pH 4, stirring speed 120 rpm, and temperature of culture media as independent variables. In addition, the effect of temperature shift cultivation strategy on yeast growth and fatty acid formation was also examined. The temperature shift strategy was carried out by growing yeast at the optimal temperature for biomass growth. Then, the cultivation temperature is lowered as the yeast enters the stationary phase. The extraction method used is sonication using chloroform and methanol solvents based on the Bligh and Dyer method to achieve optimal extraction results in a short time. The results showed that the optimum temperature for the growth of Rhodotorula glutinis was 31oC and for the formation of oleic acid was 25oC. In this study, the temperature shift strategy could increase biomass from 11.06 g/L to 11.94 g/L and increase lipid production from 3.24 g/L to 4.58 g/L but decrease oleic acid content from 47, 77% to 43%."

"Pengembangan sensor BOD dilakukan dengan elektroda glassy carbon terdeposisi partikel emas dan terimobilisasi lapisan tipis khamir Candida fukuyamaensis UICCY-247. Proses modifikasi glassy carbon dengan partikel emas dilakukan dengan proses elektrodeposisi pada potensial -300mV dengan menggunakan Multi Pulse Amperometry (MPA) terhadap Ag/AgCl. Karakterisasi dengan SEM menunjukkan ukuran partikel emas yang melapisi glassy carbon adalah sekitar 66 nm. Proses imobilisasi mikroba khamir dilakukan dengan matriks Agarose/KCl 2% yang diratakan pada permukaan membran Nafion®. Deteksi nilai oksigen yang digunakan oleh mikroorganisme dilakukan dengan teknik MPA pada potensial -600mV. Hasil pengukuran kalibrasi linier pada keadaan free cell dan keadaan terimobilisasi lapisan tipis khamir menunjukan nilai daerah kelinieran yang baik dengan nilai regresi R2 = 0,93 untuk keadaan free cell dan R2 = 0,933 untuk keadaan terimobilisasi lapisan tipis khamir. Pengukuran terhadap kestabilan lapisan tipis menunjukan bahwa pada setiap hari pengukuran, terjadi penurunan arus reduksi yang terukur sebagai akibat semakin sedikitnya jumlah sel khamir yang hidup dalam sistem. Presisi pengukuran dengan elektroda GC-Au pada 15 kali pengukuran dengan cyclic voltametry memberikan nilai RSD 18,49% untuk keadaan tanpa kehadiran sel khamir dan RSD 14,65% dalam keadaan terimobilisasi lapisan tipis sel khamir. Pengaruh kehadiran logam berat pada sistem pengukuran dilakukan dengan memvariasikan konsentrasi spesi Cu. Pengukuran dengan MPA pada -600mV terhadap Ag/AgCl menunjukan kenaikan arus reduksi terhadap kenaikan konsentrasi spesi Cu karena makin sedikit jumlah oksigen yang dapat digunakan oleh mikroorganisme akibat jumlah mikroorganisme efektif dalam sistem akan semakin sedikit. Uji kesetaraan yang dilakukan antara metode sensor BOD dan BOD konvensional menghasilkan perbandingan yang cukup baik sehingga dapat disimpulkan metode sensor BOD memiliki keakuratan pengukuran yang cukup baik.

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The development of BOD sensor conducted with glassy carbon gold particles deposited electrode and immobilized with a thin layer of yeast Candida fukuyamaensis UICCY-247. The process of glassy carbon modification with gold particles carried by the process of electrodeposition at a potential 300mV by using Multi-Pulse Amperometry (MPA) against Ag / AgCl. Characterization by SEM shows the size of gold particles lining the glassy carbon is about 66 nm. The process of microbial immobilization of yeast is done by using matrix agarose / KCl 2%, which flattened at the surface of Nafion ® membrane. Detection of oxygen used by microorganisms was done by using MPA on the potential-600mV. Linear calibration measurement results on the state of free cell and immobilized state of a thin layer of yeast showed good linearity local value with the value of regression R2 = 0.93 for the state of free cell and R2 = 0.933 for the immobilized state of a thin layer of yeast. Measurements showed that the stability of a thin layer on each day of measurement, there was a measurable decrease in flow reduction as a result of the small number of yeast cells that live within the system. Precision measurement with GC-Au electrode in 15 times of measurement by cyclic voltametry 18.49% RSD value for the state without the presence of yeast cells and 14.65% RSD in the immobilized state of a thin layer of yeast cells. Effect of the presence of heavy metals on the measurement system is done by varying the concentration of Cu species. Measurements with MPA at-600mV against Ag / AgCl showed increased flow reduction of Cu species concentration increases because the less amount of oxygen that can be used by microorganisms due to the number of effective microorganisms in the system will be less. Equivalence test conducted between the sensor BOD and BOD methods of conventional produce a pretty good ratio so it can be concluded, BOD sensor has a good accuracy on measurement."