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Articles by Tri Joko Raharjo
Total Records ( 2 ) for Tri Joko Raharjo
  Tri Joko Raharjo , Norman Yoshi Haryono , Dilin Rahayu Nataningtyas , Ery Nourika Alfiraza and Deni Pranowo
  Objective: Degenerate PCR technique has been successfully used to identify a lipase gene fragment of Alcaligenes sp. JG3. Primers were designed based on lipase genes of bacterium Azospirillum sp. B510 and Alcaligenes faecalis using PrimerBlast software. Methodology: Sequence analysis of the fragment with a size of 0.4 kb amplified using the forward primer (AlF4) 5’-GTCTACAGCAATCCCAAGAC-3’ and reversed primer (AlR4): 5’-GGAGGGGTAAATCCACAGTT-3’ represented a 394 bp nucleotide sequence which has been submitted to NCBI GenBank with Accession No. of KP872319. Results: The obtained DNA sequence was confirmed as part of lipase gene as it shared 98% amino acid and 88.07% nucleotide similarity with lipase gene of Alcaligenes faecalis, that covered approximately 27% the gene. Conclusion: The designed primers based on lipase gene of Alcaligenes faecalis were able to amplify 394 bp lipase gene fragment of bacterial strain Alcaligenes sp. JG3.
  Tri Joko Raharjo , Lizma Febrina , Fandhi Adi Wardoyo and Respati Tri Swasono
  Background: Interaction between -NH2 group of chitosan to -CHO groups of glutaraldehyde is critical in lipase immobilization using chitosan as a matrix and glutaraldehyde as a linker. Since the Deacetylation Degree (DD%) of chitosan represent the number of -NH2 group, it is important to understand the effect of the DD% value of chitosan on the effectiveness of immobilization. Chitosan beads and powder have different accessible -NH2 group, therefore, the influence of the form of chitosan is also interesting to be investigated. Materials and Methods: Three chitosans with different DD prepared with various repetition of deacetylation. This chitosan was set in beads and powder form then cross-linked to lipase (porcine’s pancreas) using glutaraldehyde as across-linking agent. The amount of the immobilized lipase as well as the hydrolytic activity of lipase was observed to determine the effectiveness of the immobilization. The thermal stability and reusability of this immobilized lipase were also investigated. Results: The optimum DD% value of powder chitosan using in lipase immobilization is at 90% DD with the optimum condition by using 1.5% of glutaraldehyde at pH 6.0 with efficiency up to 89%. The optimum DD% of beads chitosan is at 81% DD with the optimum condition by using 0.5% of glutaraldehyde at pH 6 with efficiency up to 53%. The immobilization at optimum condition of powder chitosan capable in retaining 32% of the activity, while the beads chitosan could keep 60% of the activity based on a comparison of the specific activity data. The result is corresponding to the kinetic data, where in beads the KM value is 100 mM higher than that of the free enzyme with 86 mM in KM value. Immobilization of lipase improves the stability of the enzyme with no significant reduction of activity up to five times of reuse and thermal stability up to 50°C. Conclusion: The DD% value of chitosan plays an essential role in lipase immobilization using crosslink method with glutaraldehyde as alinker with medium DD% give the best result. Immobilization of lipase improves the stability of the enzyme leading to reusability and thermal of the enzyme.
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