No abstract

The development of plastics production from biodegradable resources such as polyhydroxyalkanoates (PHAs) is important due to the increasing demand for plastics. PHAs occur as intracellular solid materials produced by microorganisms as a result of an excess of carbon source and a limitation of nutrients. Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) or PHBV, as one of the PHAs, is a combination of two homopolymers, namely poly-3-hydroxybutyrates (PHB) and poly-3-hydroxyvalerates (PHV). This study aimed to investigate the effect of the phosphorus concentration on the production of PHAs by Haloferax mediterranei. It is possible that phosphorus deficiency may affect the length of the HV chains in the copolymer structure and thus influence the copolymer properties. The experiment was done in triplicate at laboratory scale by culturing H. mediterranei in medium with phosphorus limitation using various phosphorus concentrations. During cultivation, the optical density, phosphorus concentration, pH, and dry cell weight were observed. The PHBV product was collected and analyzed using gas chromatography. The result shows that medium with a phosphorus concentration of 0.5 g/L produced higher PHAs than the other phosphorus concentrations. The accumulated PHA was 0.95 g/L with 15.6% of dry biomass and yield Y PHA/S of 0.1 g/g.

Research on making films using chitosan, nanocellulose from pineapple leaf fiber, and glutaraldehyde were carried out as an effort to obtain alternative biodegradable plastics. Chitosan has low mechanical, therefore nanocellulose is added from pineapple leaf fibers and glutaraldehyde additives. This research was conducted to obtain the optimum glutaraldehyde additive variable that functions as a crosslinker. What chitosan used was 2% (w/v solution) and nanocellulose 3% (w/w chitosan) based on optimum results from previous research. The method used a casting method, chitosan and nanocellulose are dissolved and heated in acetic acid 1% then glutaraldehyde is added during cold and cast. Variable of glutaraldehyde added by 0%, 0.5%, 1%, 2%, and 3% (w/w chitosan). Tensile strength, elongation, functional groups, and absorbance were used to characterize film. The results showed that the results of FT-IR were a spectrum of chitosan and indicated the crosslinking between chitosan and glutaraldehyde. The tensile strength values change with the addition of glutaraldehyde. The optimum value of adding glutaraldehyde is 1% based on the results of tensile strength and the lowest absorbance.

Bahan plastik biodegradable saat ini sedang populer dikembangkan untuk menggantikan plastik kemasan konvensional yang tidak ramah lingkungan. Penelitian ini bertujuan untuk mengetahui pengaruh penambahan polietilen glikol (PEG) terhadap karakteristik film berbahan dasar k-karaginan. k-karaginan yang digunakan dalam formulasi pembuatan film yaitu sebanyak 1,5% (b/v), sedangkan konsentrasi PEG yang ditambahkan bervariasi yaitu 2, 4, 6, 8, dan 10 % (b/b). Larutan dipanaskan hingga suhu 85 oC kemudian dicetak dalam bentuk film tipis, lalu didinginkan dan dikeringkan dengan oven hingga didapatkan berat konstan. Film yang diperoleh kemudian dilakukan analisis termal, kuat tarik, elongasi dan water vapor transmission rate (WVTR).  Hasil penelitian menunjukkan bahwa semakin besar polietilen glikol yang ditambahkan pada film karaginan dapat meningkatkan titik leleh dan entalpi, tetapi menurunkan nilai kuat tariknya, dan juga tidak mempengaruhi nilai WVTR. Penambahan PEG sampai konsentrasi 4% juga meningkatkan nilai elongasi film. Dari hasil pengujian diperoleh jumlah optimal penambahan PEG yaitu sebesar 4% dengan nilai kuat tarik sebesar 0,86±0,16MPa, elongasi 25,40±6,64%, dan WVTR 116,02±8,00 g/m2/24 jam.

Red seaweed has many advantages and can be utilized for cosmetics and pharmaceutical products for its rich bioactive content such as R-Phycoerythrin and phenols. This study were aimed to determine the R-phycoerythrin and phenolic contents, also the bioactivities of red seaweed extracts from Indonesia. The samples of Eucheuma sp., Gelidium sp., Eucheuma spinosum, Halymenia sp., and Rhodopeltis sp. were extracted by maceration method with distilled water (ratio 1:2, w/v) for 24 hours at cold temperature. The R-phycoerythrin content was determine by UV/VIS spectrophotometry at λ 455, 565, and 592 nm. Total Phenolic Content (TPC) was determined using Folin-Ciocalteu method. The antioxidant and antityrosinase were determined using Ferric Reducing/Antioxidant Power (FRAP) and mushroom tyrosinase assays. The highest yield of extract (2.73%, w/w) and R-PE (0.1056 mg/mL) were obtained from Halymenia sp., with highest phenolic content 8.79±1.21 GAE/mg, as well as in Eucheuma sp. (7.05±0.87 GAE/mg, p > 0,05). Halymenia sp. and Eucheuma sp. extracts showed antioxidant content of 19.40±0.37 and 19.08±0.66 AA mg/g, with tyrosinase enzymes of 40.09±2.01% and 41.36±3.8 % (1,000 ppm). Thus, Eucheuma sp. and Halymenia sp. extracts have high potential activities, while Halymenia sp. was potentialy used as natural colorant for cosmeticals and nutraceutical.