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Retno Indrati
Gadjah Mada University
Agriculture, Biological Sciences & Forestry

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Isolation of Stable Mutants of Candida guilliermondii Producing One Type of ADH Retno Indrati; Yoshiyuka Ohta
Indonesian Food and Nutrition Progress Vol 1, No 2 (1994)
Publisher : Indonesian Association of Food Technologists

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.22146/jifnp.9

Abstract

Mutants of Candida guilliermondii partially deficient in alcohol dehydrogenase (ADH) were isolated using allyl alcohol as a selective agent. On glucose medium containing allyl alcohol produced mutants deficient in ADH1, while mutants free of ADH2 were isolated on ethanol medium containing allyl alcohol. An addition of 1% of yeast extract to the isolation medium resulted in a stability of the mutants againts a high concentration of allyl alcohol. On this medium the cells resistant up to 80 mM of allyl alcohol compared to those with a resistance of 10 mM allyl alcohol on basal salt medium without addition of yeast extract. Furthermore, this resistance to allyl alcohol seems to be related to a stability of the mutants to produce only one type of ADH for a long incubation period (more than 2 years). Cells which were resistant only up to 10 mM of allyl alcohol started to produce two kind of ADHs after six months of incubation. However, this resistance to a high allyl alcohol resulted in a decrease of specific activity of ADHs. Mutant ADH1s had activities only 23 – 50%, where as mutant ADH2s had only 1 – 3% of the parent strain activity.
Production of Alkaline Lipase from Kluyvera KB4 Retno Indrati; V.S. Pertiwi Rumiyati; Tyas Utami
Indonesian Food and Nutrition Progress Vol 5, No 1 (1998)
Publisher : Indonesian Association of Food Technologists

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.22146/jifnp.59

Abstract

Kluyvera KB4 produced alkaline lipase in a medium containing oil as inducer. Optimum conditions for lipase production were determined in terms of composition of medium, pH, temperature and time of incubation. The highest lipase productivity was obtained from a medium with corn oil as carbon source and peptone as nitrogen source. Oils seem to be. an essential carbon source, since in a medium containing sorbitol without addition of oil the lipase production was very low, approximately only 14%. However, higher concentration of oil (2%) suppressed the lipase production. Production of lipase was greatly influenced by pH of the medium and incubation temperature. It was optimally active at pH 7.5 and 37 °C in medium containing peptone and corn oil 1 %, respectively. Under optimum condition (pH 7.5, at 37 °C), the highest lipase activity was obtained after 36 h of incubation.
Detection of Fish Freshness Using Immobilized ADP-ase and 5'-Nucleotidase on Polyacrylamide Gel Djagal W Marseno; Retno Indrati; Sudarmanto Sudarmanto
Indonesian Food and Nutrition Progress Vol 5, No 1 (1998)
Publisher : Indonesian Association of Food Technologists

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.22146/jifnp.54

Abstract

The presence of ADP and IMP in the muscle of fish could be used as an indicator of its freshness. These metabolites could be detected enzymaticaly using ADPase and 51-nucleotidase. The aim of this research was to determine the presence of ADP and IMP in the muscle of fish qualitatively, using immobilized ADPase and 5'-nucleotidase on polyacrylamide gel. The results showed that in the non-immobilized form, ADPase has an optimum pH of 6 and stable at pH 5.5-10, while 5'-nucleotidase has two optima pH of 6.5 and 9 and it was stable at pH 7-10. Optimum temperature of ADPase and 5'-nucleotidase was 45 and 50°C, respectively. In the immobilized form, the activity of ADPase was optimum at pH 6 and it was still stable at pH 5.5 - 7.0 after storage at -20°Cfor 90 days, while 5'-nucleotidase was still stable at pH Z5-10 after storage at -20°C for 90 days. Both enzymes were more stable in frozen storage than that of chilled storage. Sensitivity of both enzymes to detect the fish freshness during storage was affected by the presence of free inorganic phosphate derived from other phosphate-containing metabolites.
Mutation Technique for Increasing the Production of Antibacteria Lactobacillus plantarum TGR-2 Sebastian Margino; Sri Winarti; Retno Indrati; Endang S. Rahayu
Indonesian Food and Nutrition Progress Vol 5, No 2 (1998)
Publisher : Indonesian Association of Food Technologists

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.22146/jifnp.71

Abstract

Production of antibacteria of Lactobacillus plantarum TGR-2 was carried out by mutation technique using UV radiation and chemical mutagenic agent (acrydine orange (AO), ethyl methane sulfonate (EMS), and N-methyl-N-nitro sulfonate nitrosoguanidine (NTG). As a marker was applied chloramphenicol for 10 ppm. Total 214 mutants were obtained from all of the treatments and then screened based on their activities against Staphylococcus aureus FNCC 0047 as bacterial indicator, using agar diffusion and turbidimetric assay techniques. Results showed that 24 mutants could produce higher amount of antibacteria and two of them, NTG and acrydine orange treatments, had higher stability than others. Characterization of two mutants, determination of biochemistry traits and optimization of antibacterial (bacteriocin) production were done. The product showed that UV-15, EMS-10, AO-6 and NTG-21 mutants could produce antibacterial substance 3,90, 4.40, 3.40 and 4.17 AU/ml for 16, 12, 12, and 16 hours incubation, respectively, compared to Lactobacillus plantarum TGR-2 which produced 1.07 UA/ ml for 24 hours incubation.
A Simplified Method for Determination of Free Fatty Acids for Soluble and Immobilized Lipase Assay Djagal W. Marseno; Retno Indrati; Yoshiyuki Ohta
Indonesian Food and Nutrition Progress Vol 5, No 2 (1998)
Publisher : Indonesian Association of Food Technologists

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.22146/jifnp.77

Abstract

A simple and rapid method for determination of free fatty acids for soluble and immobilized lipase assay was developed. The free fatty acids could be determined within 10 min with less organic solvent used and the color developed was stable until 60 min. High correlation (r > 0.97) between fatty acids content (2 -10 pmole) and absorbance was observed for fatty acids with carbon number of 6 or higher. Hydrolysis activity of soluble and immobilized lipase could be measured with high sensitivity and reproducibility against incubation time and protein loading. The effect of various substrate concentrations and water against hydrolysis activity could also be measured. The method was suitable for routine analysis such as purification of lipase and continuous hydrolysis of fat and oil.
Utilization of ATP and Its Derivatives as an Index of Freshness of Nila (Oreochromis niloticus) During Storage Djagal W Marseno; Sudarmanto Sudarmanto; Retno Indrati
Indonesian Food and Nutrition Progress Vol 6, No 1 (1999)
Publisher : Indonesian Association of Food Technologists

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.22146/jifnp.75

Abstract

The role of a reliable and reproducible, index of fish freshness, is important. The objective of this research was to examine the utilisation of ATP and its derivatives (expressed as K-value) as an index offish freshness using Nila (Oreochromis niloticus) as a model of study. K-value is [(Inosine + Hypoxanthine) / (ATP + ADP + AMP + IMP + Inosine + Hypoxanthine)] x 100%. Live fish were killed, packed individually using polyethylene bag and stored at 4 and 28°C. At defined time, some fishes were examined their ATP and its breakdown products using a reverse phase HPLC system. The results showed that ATP, ADP and AMP were degraded rapidly and disappeared within 12 ho urs. Degradation of IMP in the samples stored at 4°C was slower than those of samples stored at 28°C. Interestingly, the accumulation of Inosine occurs only in the samples stored at 28°C while the accumulation of Hypoxanthine occurs only in the samples stored at 4"C. The data suggested that the activity of IMP-degrading enzyme (5'-nucleotidase) at 4"C was higher than that of Inosine-degrading enzyme, but at 28°C both enzymes have similar activities. Linear regression analysis between K-value and storage time showed that increasing rate of K-value or rate of the lowering freshness of samples stored at 28"C was 4 times higher than that of samples stored at 4°C. Limits offish acceptability (K-value 60%) of Nila stored at 28 and 4"C were reached at 12 and 72 hours, respectively. The results confirmed that K-value was the best as an index offish freshness compared with IMP, Inosine and Hypoxanthine and it could be used as an index of freshness of Nila (Oreochromis niloticus) during storage.
Immobilization of Lipase from Rhizopus delemar on Polyethylene Membrane Retno Indrati; Djagal W Marseno; Yoshiyuki Ohta
Indonesian Food and Nutrition Progress Vol 6, No 1 (1999)
Publisher : Indonesian Association of Food Technologists

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.22146/jifnp.67

Abstract

Rhizopus delemar lipase was immobilized by physical adsorption onto polyethylene membranes. The influence of membrane pore size and thickness on enzyme activity was studied. The immobilization efficiency was higher for the thicker membrane than thin one, this related to the large excess of area that the enzyme can occupy. The immobilization efficiency was also affected by enzyme loading, in which suppression was occurred at high enzyme loading. At the initial rate of hydrolysis reaction, the amount of enzyme bound, concentration of substrate, and membrane's thickness as related to the limitation of the substrate transfer affected the production of fatty acid. The thin polyethylene membrane was the best support since the enzyme immobilized on this support was stable during storage and possessed higher degree of hydrolysis and ability for subsequent reuses. Both membranes were regenerable by washing for fresh enzyme immobilization.
Co-Authors Djagal W Marseno Djagal W. Marseno Endang S. Rahayu Sebastian Margino Sri Winarti Sudarmanto Sudarmanto Tyas Utami V.S. Pertiwi Rumiyati Yoshiyuka Ohta Yoshiyuki Ohta