Nengah Dwianita Kuswytasari

Lipase production in lipolytic yeast from Wonorejo mangrove area

Lipase is an enzyme that is often used in industry and become a commercial enzyme. One group of microorganisms capable of producing lipase is a yeast. This study aims to screen yeast from Wonorejo mangrove that potential to produce lipase and to optimize the production of these enzymes. Screening test include the measurement of lipolytic index and value of fatty acid. Yeast with the best value of fatty acid will be continued to the measurement of lipase activity. It is affected by several environmental factors, such as pH, temperature, and incubation time. This research was conducted to observe the optimization variation on environmental factors combination to produce lipase. Lipase activity was tested by using p-Nitrophenyl Palmitate (pNPP). Absorbency was measured by spectrofotometer on wavelength of 410 nm. Measurement of the enzyme activity was done by interpolating the absorbance values on the p-nitrophenol standard curve then calculated by the formula. All data were analyzed by using descriptive qua...

Soil burial method for plastic degradation performed by Pseudomonas PL-01, Bacillus PL-01, and indigenous bacteria

Lately, plastic bag is becoming the most important pollutant for environment since it is difficult to be naturally degraded due to it consists of long hydrocarbon polymer chains. Our previous study indicated that our pure isolate Pseudomonas PL-01 and Bacillus PL-01 could degrade about 10% plastic bag. This present study was aimed to find out whether Pseudomonas PL01 and Bacillus PL01 put a positive effect to indigenous bacteria from marginal area in doing plastic degradation with a soil burial method. Beach sand was used as a representative marginal area, and mangrove sediment was used as a comparison. Plastics were submerged into unsterile beach sand with 10% of Pseudomonas PL-01 or Bacillus PL-01 containing liquid minimal salt medium (MSM) separately, while other plastics were submerged into unsterile mangrove sediments. After 4, 8, 12 and 16 weeks, their biofilm formation on their plastic surfaces and plastic degradation were measured. Results indicated that those 2 isolates put positive influent on b...

Diversity of heavy metal resistant bacteria from Kalimas Surabaya: A phylogenetic taxonomy approach

Bacterial resistance to heavy metal is a genetic and physiological adaptation to the environment which contaminated by heavy metal. Kalimas is an important river in Surabaya that is contaminated by some heavy metals and probably as a habitat for heavy metal resistance bacteria. Bacterial resistance to heavy metals are different for each species, and their diversity can be studied by phylogenetic taxonomy approach. Isolates screening was done using nutrient agar which contained 1 mg/L HgCl2, CdCl2 and K2Cr2O7. Bacterial viability were observed by nutrient broth which contained 10 mg/L HgCl2, 30 mg/L CdCl2 and 50 mg/L K2Cr2O7. Isolates that resistant to heavy metal and viable after exposure to heavy metal were identified using 16S rRNA gene marker by Polymerase Chain Reaction (PCR). Phylogenetic tree reconstruction was done by the neighbor-joining algorithm. Genetic assignment showed isolates that resist and viable after exposure of Hg, Cd and Cr are Bacillus S1, SS19 and DA11. Based on BLAST analysis from ...

Viability of Azotobacter consortium in auxin production

Azotobacter is a kind of rhizobacteria which is abundant in soil and having beneficial for plants due to its ability to produce auxin. Each isolated Azotobacter from Eco Urban Farming ITS were able to produce auxin individually. However, the isolated Azotobacter consortium was prefer to produce more auxin than the individual one. Synergism test were carried out in order to verify non-antagonism among Azotobacter isolates. Auxin production test was conducted by inoculating 100 ml of Azotobacter consortium starter in 400 ml nutrient broth by addition of 1.000 ppm of L-tryptophan while shaking 100 rpm in rotary shaker at room temperature for 8 weeks. Auxin concentration was measured spectrophotometrically according to the Salkowski method. The Azotobacter consortium showed living synergistically and able to produce 1,82 ppm auxin in 2 hours incubation time although the concentration was tend to decrease periodically.