UJI KEMAMPUAN Lactobacillus casei SEBAGAI AGENSIA PROBIOTIK

Growth Ability of Jatropha Curcas L. Explants on the In Vitro Media Containing IBA and BAProbiotic product is one of the applications of biotechnology that utilize lactic acid bacteria, especially lactobacilli. Some important requirements for microbes that can be used as probiotic include resistance to low pH, ability to grow on bile salts and colonize, and having antimicrobial activity. Each species of the genus Lactobacillus has different characteristics. These characteristics are strongly influenced by the environment in which the bacteria live. This study was carried out in order to characterize Lactobacillus casei which was isolated from dadih. The result of the experiment showed that the isolated L. casei was able to grow on the bile salt at the concentration of 15%, resistant to acid media until pH 2, had antimicrobial activity (significantly inhibited the growth of Escherichia coli, Staphylococcus aureus, and Enterococcus faecalis). The local L. casei isolate has a potential application for use as probiotic microbe.Keywords: Lactobacillus casei, probiotic, lactic acid bacteria, characterization,dadih ABSTRAKProduk probiotik merupakan salah satu aplikasi bioteknologi yang memanfaatkan bakteri asam laktat terutama jenis Lactobacillus. Beberapa syarat utama mikroba yang dapat difungsikan sebagai mikroba probiotik antara lain tahan terhadap pH rendah, mampu tumbuh pada garam empedu, mampu berkoloni, memiliki aktivitas antimikroba. Masing-masing spesies dari Genus Lactobacillus memiliki karakteristik yang berbeda-beda. Karakteristik ini sangat dipengaruhi oleh lingkungan dimana bakteri tersebut hidup. Pada penelitian ini telah dilakukan karakterisasi Lactobacillus casei yang merupakan hasil isolasi dari susu kerbau fermentasi. Dari hasil percobaan menunjukkan bahwa L.casei hasil isolasi mampu hidup sampai dengan konsentrasi garam empedu 15%, tahan terhadap media asam sampai dengan pH 2, memiliki aktivitas antimikroba (positif menghambat Escherichia coli, Staphylococcus aureus, dan Enterococcus faecalis). L. casei yang merupakan isolat lokal memiliki karakteristik yang berpotensi untuk digunakan sebagai mikroba probiotik.Kata kunci: Lactobacillus casei, probiotik, bakteri asam laktat, karakterisasi, dadi

PENGARUH VARIASI KONSENTRASI METANOL DAN LAMA INDUKSI TERHADAP EKSPRESI PROINSULIN OLEH Pichia pastoris SECARA INTRASELULER

The Effects of Variation in Methanol Concentration and Induction Time on Intracellular Proinsulin Expression by Pichia pastoris ABSTRACTDiabetes is a metabolic disorder characterized by hyperglycemia. There were 215 million diabetic patients in 2014 and the number is expected to rise in 2040. Generally, insulin is used to treat diabetic patients. Insulin production by recombinant technology has been done, though still inefficient, by using E. coli and S. cerevisiae expression system. Another alternative expression system is methylotrophic yeast Pichia pastoris. In this research, proinsulin has been expressed by P. pastoris intracellularly. P. pastoris strains used in this research were X33, GS115, and KM71H. All recombinant strains were MutS. Best cultivation media was BMGY. Proinsulin expression was observed at 25°C. Pichia pastoris strain that expressed proinsulin best was GS115-PI. It was supported by PCR in which the strain GS115-PI gave 504 bp-sized bands. Based on proinsulin formation time, the final methanol concentration of 0.5% in 72 hours was found to be the best treatment.Keywords: BMGY, methanol, phenotype, Pichia pastoris, proinsulin ABSTRAKDiabetes melitus merupakan kelainan yang ditandai dengan hiperglikemia. Penderita diabetes pada tahun 2014 di dunia mencapai 215 juta dan diperkirakan akan meningkat pada tahun 2040. Umumnya penderita diabetes diberi pengobatan insulin sehingga menunjukkan akan ada peningkatan kebutuhan insulin. Produksi insulin dengan teknologi DNA rekombinan telah dilakukan dengan menggunakan sistem ekspresi E. coli dan S. cerevisiae namun masih belum efisien. Sistem alternatif lain adalah ragi metilotropik Pichia pastoris. Dalam penelitian ini dilakukan ekspresi proinsulin dari P. pastoris secara intraseluler. Galur P. pastoris yang digunakan dalam penelitian ini adalah X33, GS115, dan KM71H. Semua galur rekombinan adalah MutS. Media tumbuh terbaik adalah BMGY. Ekspresi proinsulin terlihat pada suhu 25°C. Hasil PCR menunjukkan bahwa galur GS115-PI yang dapat menghasilkan pita amplikon berukuran 504 bp. Hasil PCR ini dibuktikan oleh hasil seleksi galur yang menunjukkan bahwa galur GS115-PI dapat mengekspresi proinsulin dibandingkan galur lainnya. Berdasarkan kecepatan pembentukan pita protein proinsulin, variasi konsentrasi akhir metanol 0,5% dengan lama induksi 72 jam merupakan perlakuan terbaik.Kata Kunci: BMGY, fenotipe, metanol, Pichia pastoris, proinsuli

Cloning and Extracellular Expression of Glargine in Pichia pastoris

Patients with diabetes mellitus increase significantly every year. The increasing number of people with diabetes mellitus results in increased insulin requirements. There are two types of insulin used for diabetes mellitus treatment: human insulin and insulin analogues. Escherichia coli, Pichia pastoris, Saccharomyces cerevisiae, or Hansenula polymorpaha has been used to produce human insulin and insulin analogues. Pichia pastoris can produce glargine in large quantities, and the insulin protein produced will be secreted outside the cell to facilitate the purification process. The advantage of glargine has a long working time of up to 24 hours. Hence, glargine is more effective because patients with diabetes receive glargine injections only once daily. The research started with cloning the glargine gene, transforming pPICZαA-G plasmid into Pichia pastoris, and testing glargine production. 20 recombinant Pichia pastoris colonies were selected and regenerated. Eight recombinant Pichia pastoris colonies were tested for glargine production, and six colonies were detected producing glargine by electrophoresis SDS-PAGE gel stained with Coomassie blue. This study aims to produce glargine using Pichia pastoris as an expression system capable of producing glargine extracellularly, thus simplifying the purification process