EKSTRAK AIR LIMBAH TAHU SEBAGAI SUBSTRAT ALTERNATIF PERTUMBUHAN Acetobacter xylinum UNTUK SINTESIS POLISAKARIDA EKSTRASELULER (Nata de Tofu)

RETNO SETYASTI, Prof. Dr. A. Endang Sutariningsih Soetarto, M.Sc., Ph.D.

2014 | Skripsi | BIOLOGI

Limbah tahu merupakan hasil samping pabrik tahu meliputi limbah padat dan cair. Limbah tahu tersebut mengandung bahan organik yang terdiri dari karbohidrat (12-30%), protein (35-45%0, lemak (18-32%) ;bahan anorganik atau mineral, senyawa nitrogenous (1,15%), fosfor (0,18%), kalsium (0,19%), besi (0,04%) dan air (0,09%) yang relatif tinggi. Berdasarkan kandungan nutrien yang cukup tinggi tersebut, limbah tahu mempunyai potensi sebagai substrat alternatif untuk pertumbuhan bakteri tertentu khususnya Acetobacter xylinum. Tujuan penelitian adalah memanfaatkan limbah padat tahu sebagai medium pertumbuhan Acetobacter xylinum penghasil nata yang disebut Nata de Tofu. Penelitian diawali dengan analisis kimia limbah tahu terkait dengan kualitas limbah (kandungan C organik). Penyiapan limbah padat tahu sebagai substrat pertumbuhan Acetobacter xylinum, dilakukan melalui beberapa perlakuan, perlakuan perendaman air atau fermentasi dengan limbah cair sebagai sumber inokulan. Masing-masing perlakuan diekstrak dan digunakan sebagai media pertumbuhan A.xylinum dan sintesis nata. Kemampuan tumbuh A.xylinum dan sintesis polisakarida ekstraseluler diuji melalui percobaan menggunakan medium ekstrak hasil perlakuan limbah. Tiap interfal waktu tertentu pertumbuhan diukur berdasarkan ketebalan polisakarida ekstraseluler yang terbentuk, perubahan pH dan kadar asam total serta kadar gula reduksi dianalisis dengan metode DNS. Kualitas nata yang dihasilkan diamati berdasarkan kekuatan daya tarik dan kerentangan. Hasil penelitian menunjukkan bahwa kadar gula reduksi hasil ekstraksi dari perlakuan perendaman air dan fermentasi spontan berbeda. Kadar gula reduksi pada ekstrak hasil fermentasi limba cair lebih tinggi (108,22 g/L) daripada yang direndam air (104,9 g/L) dan pH kedua perlakuan ini mencapai 3,2-3,8. A.xylinum mampu tumbuh dengan relatif cepat dan telah membentuk lapisan biomassa setelah 48 jam inkubasi. Nata terbentuk cukup tebal masing-masing 25- 27 mm setelah 2 minggu inkubasi, dengan daya tarik dan kerentangan masing-maing mencapai (21 N dan 28 N) serta (28% dan 52%). Kesimpulan penelitian ini adalah perlakuan fermentasi spontan limbah padat dengan limbah cair dan perendaman air menghasilkan substrat pertumbuhan A.xylinum untuk menghasilkan Nata de Tofu yang berkualitas.

The tofu industry produce more wastes rather than tofu production. Tofu industrial wastes consisted of solid and liquid wastes, containing a lot of organic compounds such as carbohydrates (12-30%), proteins (35-35%), fats (18-32%) and inorganic compounds or minerals included nitrogenous compounds (1,15%), phosphates (0,18%), calcium (0,19%), iron (0,04%), water (0,09%) and very low pH. Based on pH and nutrient contents, those waste had a potential environmental pollutants. In order to remove pollutants, many efforts had been done by physically, chemically and biologically treatments. One alternative way to utilize those wastes was to be used Acetobacter xylinum. Under low pH Acetobacter xylinum could grow and form extracellular polysaccharide called nata. The aims of the research were to utilize solid waste from tofu home industry as media for Acetobacter xylinum producing nata; and to observe the effects of waste treatments on the growth of Acetobacter xylinum and nata formation. The research commenced by preparation of bacterial growth medium from solid waste. Solid waste treatment was conducted through spontaneous fermentation by soaking them in liquid waste or in tap water for 48 hours. The treated wastes aliquots extracted through filtering were used as culture media. Reducing sugar of aliquots was analyzed using DNS method. Acetobacter xylinum was grown on 10 ml of each medium containing fermented aliquot or soaked water aliquot, incubated at room temperature for 48 h; as stock cultures. To test Acetobacter xylinum growth ability on liquid medium was carried out through cultivation experiment using those prepared liquid media. The bacterial growth was measured based on biomassa formation (colony thickness, tensile strength and elongation); reducing sugar content and the changed of pH. The results of this research revealed that different treatment of solid waste produced reducing sugar content varied. Reducing sugar in aliquot of spontaneous fermented and of water soaking treatment waste solid tofu contained 108,22 g/L and 104,9 g/L, with pH 3.2-3.8 respectively. Both media stimulated Acetobacter xylinum to grow and nata formation. The end of exponential growth phase of those cultures, the thickness of nata formed was 25 & 27 mm; nata tensile strengths of 28 N & 21 N with the elongation about 52% & 28%, respectively. The conclusion of this research was the home tofu industry solid wastes treated by fermentation could be used as Acetobacter xylinum growth and promising substrate for nata formation called Nata de Tofu.

Kata Kunci : Limbah tahu, Acetobacter xylinum, kadar gula reduksi, pH