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Enhancing TK rubber extraction efficiency with fungus and enzyme treatments

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2018, Master of Science, Ohio State University, Food, Agricultural and Biological Engineering.
Natural rubber (cis-1, 4-polyisoprene), an important strategic resource, is widely used in the manufacturing and medical industries. However, efforts have been made to find alternative rubber producing resources because the present sole commercial rubber resource, Hevea brasiliensis, has many potential problems, like unstable supply, pathogen attack, rising price, restricted growth range, labor intensive processing and sensitivity to environmental stress. Taraxaxum kok-saghyz (TK), which contains rubber in its roots, is considered one of the most promising alternative rubber resources. To extract the rubber from TK roots, the extraction process must be designed to optimize both yield and purity. The Eskew water-based extraction method used in the past, extracts rubber contaminated with tightly bound lignocellulosic debris. In this study, Thermomyces lanuginosus, a thermophilic fungus discovered in self-heating organic debris, was used in the rubber extraction process to hydrolyze non-rubber root material and increase rubber yield and purity. The rubber was extracted from dried TK roots using process similar to the Eskew process that included alkaline pretreatment, inulin extraction, grinding, inoculation (fungus or enzymes), incubation and filtration. The control was the same process without inoculation. The rubber yield and purity of the fungus treatment were 64.24 ± 0.97 mg/g, 84.35 % of theoretical yield (76.16 mg/g), and 85.45 ± 6.98 % while rubber yield and purity of the control were 34.58 ± 0.26 mg/g and 65.08 ± 2.69 %, respectively. The crude fungal enzyme preparation (CF) and other cellulases like E1 (an overexpressed endocellulase contained in ground maize defatted germ flour), E1+CBH1 (an overexpressed exocellulase contained in maize full fat germ), XC-150 (commercial cellulase from CTE Global Inc.), Cellic CTec2 (commercial cellulase complex from Novozymes) were also applied to the extraction process separately. Two units of CTec2, CF, XC-150, E1, E1+CBH1(1:1) and 6.5 days of incubation resulted in rubber yields of 93.71 %, 91.08 %, 89.06 %, 81.70 %, 81.04 % of theoretical (56.60 mg/g) respectively. Four units of CTec2, XC-150, CF, E1, E1+CBH1(1:1) and 3.25 days treatment resulted in the recovery of 94.32 %, 92.24 %, 91.82 %, 82.77 %, 81.63 % of the theoretical rubber yield (56.60 mg/g) respectively. The purities of the rubber samples produced by 2 units of XC-150, Ctec2, E1, E1+CBH1 (1:1), CF and 6.5 days treatment were 91.62 %, 88.06 %, 85.89 %, 77.19 % and 75.48 %. The purities of the rubber samples produced using 4 units of XC-150, Ctec2, E1+CBH1(1:1), E1 or CF after 3.25 days of treatment were 89.43 % 84.03 %, 79.53 %, 77.56 % and 74.32 %. The rubber yield and purity of the control were low (21.46 mg/g and 48.46 %) and the reason may be that improper grinding time (3s) was applied. All the fungus and enzyme treatments are a great improvement over the previously reported Eskew method. Fungus and fungus crude enzyme treatments significantly increased the rubber purity similar to maize expressed cellulases. As an exception, two units of E1 performed as well as commercial cellulases (XC-150 and Cellic Ctec2) followed by E1+CBH1 and crude fungus enzymes. However, rubber yield was not significantly different among fungal or maize-derived enzymes and commercial cellulases. The process was further improved by optimizing the incubation temperature (based on inoculum) and the grinding time (chopped or 20 s). In summary, T. lanuginosus and its crude enzyme extracts as well as maize-derived and commercial cellulases increased the yield and purity of rubber extracted from TK roots compared with the Eskew method.
Katrina Cornish (Advisor)
Frederick Michel (Committee Member)
Thaddeus Ezeji (Committee Member)
89 p.

Recommended Citations

Citations

  • Liu, P. (2018). Enhancing TK rubber extraction efficiency with fungus and enzyme treatments [Master's thesis, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1515162731667997

    APA Style (7th edition)

  • Liu, Pailing. Enhancing TK rubber extraction efficiency with fungus and enzyme treatments. 2018. Ohio State University, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1515162731667997.

    MLA Style (8th edition)

  • Liu, Pailing. "Enhancing TK rubber extraction efficiency with fungus and enzyme treatments." Master's thesis, Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1515162731667997

    Chicago Manual of Style (17th edition)