Radipta Lailatussifa, Amir Husni, and Alim Isnansetyo

Abstract

This research aims to know antioxidant activity, total phenolic, nutrient, and screening phytochemistry compounds of S. hystrix dry powder. Water extract from the dried sample of brown algae (S. hystrix) was prepared and examined for its phenolic compounds. The amount of total phenolic compounds in water extract was about 11.43 g Gallic Acid Equivalent (GAE)/100 g of dry basis sample, as measured by using Folin-Ciocalteu method. The antioxidant activity (Radical Scavenging Activity/RSA) of BHT as a standard was high about 96% inhibition of radical DPPH with 1 mg dry sample/ml solvent. The IC50 of the BHT was 0.227 ± 0.001 mg of dry sample/ ml solvent. While the radical activity (RSA) of S. hystrix dry powder was about 65.28% at 1 mg dry sample/ml solvent. The IC50 of S. hystrix dry powder was 0.616 ± 0.005 mg of dry sample/ml solvent. Nutrient contents and bioactive compounds of dry powder S. hystrix were balanced to support antioxidant activity of the sample. The results suggest that this alga is a potential source of natural antioxidant.

Keywords: Antioxidant activity; Sargassum hystrix dry powder; phytochemistry; the phenolic; compound nutrient contents

Jurnal Perikanan Universitas Gadjah Mada 19 (1): 29-37 Full text

Theodora Linggaryati Gotama, Amir Husni, and Ustadi

Abstract

The objective of this research was to determine the potential effects of Sargassum hystrix extracts (SHE) on the glucose levels, lipid profile, and pancreas of streptozotocin (STZ)-induced diabetic rats. SHE at 200, 300, and 400 mg/kg was administered orally to STZ-induced diabetic rats once daily for 15 days. Glucose levels, lipid profile, and weight of rats were measured in the normal state and on the 15th day. The histology of the pancreas was observed on the 15th day. The results showed that the preprandial and postprandial glucose levels in the group treated with SHE at 300 mg/kg were significantly reduced compared with those of the diabetes group. Additionally, the levels of triglycerides and cholesterol in the 300 mg/kg SHE group were significantly different from those in the diabetes group. However, the levels of high-density lipoprotein cholesterol and low-density lipoprotein cholesterol across the treatment groups did not have significant differences. Necrosis was found in all STZ-induced rats. SHE at a dose of 300 mg/kg had the best capability to lower the levels of preprandial and postprandial glucose and to prevent necrosis in diabetic rats. read more

Growth Rate and Histamine Production of Klebsiella sp. CK02 Isolated from Skipjack Tuna Compared with Morganella morganii ATCC 25830 at Various Incubation Temperatures

Aldino Dityanawarman, Indun Dewi Puspita, Susana Endah Ratnawati, Nurfitri Ekantari, and Mark Tamplin

Abstract

One of an important quality parameter in tuna is the level of histamine content. The contamination of histamine in tuna is mainly due to the activity of histidine decarboxylase produced by the bacteria. A rapid growth of histamine producing bacteria is correlated with the practice of temperature abuse during handling. This study aimed to develop predictive growth modeling of two histamine-producing bacteria in the function of temperature. The growth and histamine production of Klebsiella sp. CK02 and Morganella morganii ATCC 25830 at various temperatures were measured in tryptic soy broth histidine (TSBH) and tuna fish infusion broth (TFIB) growth media. Broths were incubated at 4°C and 15°C for 7 days, and at 30°C and 40°C for 24 hours. The Baranyi and Roberts model was used with DMFit to determine primary growth kinectics, and the Ratkowsky square root model to describe bacterial growth rate as a function of temperature. Histamine production was enumerated by the apparent yield factor (pYhis/ CFU) value. Growth rate increased with temperature, with a maximum rate at 40°C for Klebsiella sp. CK02 (0.740 log CFU/h) and M. morganii (0.578 log CFU/h). The Tmin for Klebsiella sp. CK02 in TFIB was -8.9°C, indicating better survival in low storage temperature, compare to M. morganii ATCC 25830. In addition, Klebsiella sp. CK02 produced a lower pYhis/CFU at 15 and 30°C compared to M. morganii ATCC 25830.
Keywords: growth rate, temperature, histamine, Klebsiella sp. CK02, M. morganii ATCC 25830 read more

Prihati Sih Nugraheni, Alexander H. Soeriyadi, Ustadi Ustadi, Wahyudi Budi Sediawan, Wiratni Budhijanto

Abstract

Chitosan is known as an antibacterial agent. The effective surface area ratio of chitosan can be increased by modification into nanoparticles. Nano-chitosan can be prepared with several simple methods, i.e. precipitation, ionic gelation, or the polyelectrolyte complex method. This study compared these three methods in terms of the targeted product characteristics, i.e. stability of the average nanoparticle size as well as the colloidal dispersion, and the antibacterial characteristics. All three methods resulted in nanoparticle formation, but in the precipitation method significant zeta potential reduction was observed due to the presence of negative ions from the alkali that neutralized the chitosan amine group. The ionic gelation method yielded higher zeta potential and higher inhibition of bacterial growth than those yielded by the polyelectrolyte complex method. Ionic gelation and the polyelectrolyte complex method resulted in much better colloidal dispersion stability than the precipitation method, where a significant particle size increase was observed after one week of storage. This result indicates that both ionic gelation and the polyelectrolyte complex method can be used for forming nano-chitosan for the purpose of food preservation. However, for fishery products it is advisable to use the polyelectrolyte complex method because the TPP usually used in ionic gelation is not allowed to be applied to fish. read more

Akhmad Awaludin Agustiar, Imas Faturrohmah, Bekti Wulan Sari, Nurul Binti Isnaini, Indun Dewi Puspita, Triyanto Triyanto, Amir Husni, and Ustadi Ustadi

Abstract

Chitin hydrolysate is one of the value added product derived from shrimp shell waste. Production of chitin hydrolysate using biological process offers an environmental friendly method compared to chemical process. Serratia marcescens PT-6, a gram negative chitinolytic bacterium isolated from shrimp pond sediment, shows good activity in hydrolyzing chitin. This study aimed to improve the chitinase activity of S. marcescens PT-6 culture by optimizing the component of chitin-containing medium (additional nitrogen source, additional carbon source, and colloidal chitin). The optimization of chitinase by S. marcescens PT-6 culture was done using one variable at a time method. The sequence of the research were to optimize 1) the type of additional carbon source (glucose, lactose, sucrose, and starch), 2) the type of additional nitrogen source (yeast extract, peptone, ammonium sulphate, and ammonium chloride), 3) the concentration of colloidal chitin (0.5; 1; 1.5; 2; and 2.5%), and 4) the concentration of the additional carbon and nitrogen source. The culture of S. marcescens PT-6 was incubated in colloidal chitin medium at 30 oC and chitinase activity from culture supernatant was analyzed. The results showed that starch gave the highest chitinase activity compare to other carbon source, meanwhile yeast extract was chosen as the best nitrogen source among others. The combination of 1.5% colloidal chitin with 0.5% starch and 0.1% yeast extract in medium increased the chitinase activity of S. marcescens PT-6 to 0.021 U/ml. These results indicated that an appropriate medium composition could increase the chitinase activity produced by S. marcescens PT-6 culture.

Keywords: chitinase, colloidal chitin, S. marcescens PT-6, starch, yeast extract

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Indun Dewi Puspita, Ari Wardani, RR. Oki Arum Puspitasari, Prihati Sih Nugraheni, Mgs. Muhammad Prima Putra, Sri Pudjiraharti, and Ustadi

Abstract

The objectives of this research were to isolate chitinolytic bacteria from shrimp rusip (an Indonesian traditional fermented shrimp product), identify bacterial isolates showing high chitinolytic activity, and determine the chitinolytic activity of these isolates. There were 44 chitinolytic bacteria isolated from shrimp rusip: 39 isolates of Gram-positive bacteria and 5 isolates of Gram-negative bacteria. The quantitative method we used to evaluate chitin-degrading enzyme activity measured the amount of N-acetylglucosamine produced from the reaction of crude enzyme and colloidal chitin. Seven isolates showing highest chitinolytic activity were Bacillus cereus (KKT 1, KKT 14, and KKT 19), Bacillus thuringiensis (KKT 6), Enterobacter cloacae (LCK 20), Pseudomonas stutzeri (LCK 17), and Stenotrophomonas maltophilia (THK1). The highest chitinolytic activity showed by KKT 1, KKT 6, KKT 14, KKT 19, and THK 1 were 0.0016 U/mL (at 72 hours); 0.0018 U/mL (at 48 hours); 0.0019 U/mL (at 48 hours); 0.0033 U/mL (at 48 hours); and 0.0032 U/mL (at 24 hours), respectively. Keywords: chitinase activity, chitinolytic bacteria, shrimp rusip Biodiversitas 18: 1275-1281. Full text