Judul: Kajian rasio C/N terhadap produksi bioinsektisida dari Bacillus thuringiensis subsp. aizawai menggunakan substrat limbah cair tahu dan air kelapa
Abstrak: Bioinsecticide is an active substance from biological agent that kills insects and disease vector. Bioinsecticide or microbial insecticide can be developed from bacteria, virus, mushroom, and protozoa. Bacteria that often used to produce bioinsecticide is Bacillus thuringiensis (B.t). Bacillus thuringiensis subsp. aizawai (B.t.a) as one of Bacillus thuringiensis species produces crystal protein called delta endotoxin (δ-endotoxin). As other B.t crystal protein, this crystal protein is specifically toxic to larvae Lepidoptera and Diptera. Bioinsecticide is an alternatif solution, because it cannot cause pests resistance, does not make residue to the environment and does not kill non target organisms. This research aims to produce an active material bioinsecticide that is produced by B.t.a using tofu liquid waste and coconut water, which is cheap material can be used as nitrogen and carbon sources and it has protein, vitamin, mineral that are needed by microorganism to grow. Coconut water as fermentable sugar in fermentation bioinsecticide. The specific objective of this research is to obtain the best media formulation with optimal C/N ratio for bioinsecticide production. Carbon-nitrogen ratios in this research are A (3:1), B (5:1), C(7:1), D (9:1), and E (11:1), with 80 : 20 composition of liquid waste of industrial tofu and coconut water, the starter added 10 (%v/v) and cultivation time during 0-72 hours. The highest toxicity of the product can be resulted through bioassay test to Crocidolomia pavonana (C. binotalis) larvae instar-II. The pH value and weight of dry biomass during cultivation was increased while total sugars and OD (Optical Density) is decreased. Range of pH value from 6.5-7.96. For cultivation 0 hours the highest of dry cell biomass is media A (C/N=3:1) 0.60 g/L whereas the lowest is media B (C:N=5:1) and C (C/N=7:1) 0.40 g/L and for cultivation 72 hours the highest of biomass is media C (C/N=7:1) 15.90 g/L whereas the lowest is media A (C/N=3:1) 7.55 g/L. For cultivation 0 hours the highest OD is media D (C/N=9:1) 0.0214 and the end of cultivation the highest OD is media B (C/N=5:1) 2.91. The highest total plate count (TPC) is media C (C/N=7:1) 2.8 x 108 cell/ml or 7.40 cfu/ml in cultivation 48 hours whereas the lowest is media B (C/N=5:1) 1.19 x 107 cell/ml or 6.68 cfu/ml in cultivation 0 hours. The highest viable spore count (VSC) is media D (C/N=9:1) 5.63 x 106 spore/ml in cultivation 48 hours whereas the lowest is media C (C/N=7:1) 2.85x 106 spore/ml in cultivation 24 hours. The highest level toxicity (LC50) is media C (C/N=7:1) 0.01 mg/L in cultivation 48 hours and potential product is 80,000 IU/mg. The level toxicity (LC50) is contrary to potential product.
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Judul: Penentuan Rasio C/N dan Pengembangan Produksi Bioinsektisida oleh Bacillus thuringiensis Menggunakan Media Kultivasi Limbah Industri Tahu
Abstrak: Development and application of local product biopesticide, especially based on B. thuringiensis (Bt) still has been considerable potential. This is supported by the local availability of Bt local strains and agro-based raw materials are abundant and not expensive. Research toward utilization of industrial waste of tofu as a medium of cultivation of Bt has been done. In the early stages the Bt strains are isolated and selected. Bt B2 bacteria from the culture collection, protein crystals form bipiramid and cubes, are strains with the highest toxicity against C. binotalis. The optimization of media formulation is performed on a scale of 500 ml with a variation of C/N ratio 3:1, 5:1, 7:1, 9:1 and 11:1. B2 strains provides optimum toxicity value at C/N ratio 7:1 with LC50 value of 0.90 mg/L or 8356 IU/mg. The results of cultivation on the bioreactor 3 L shows substrate utilization efficiency of 67.77 % with LC50 value of 3.56 g/ml or 2112 IU/mg. Characterization of δ-endotoxin with SDS-PAGE indicates protein pattern at all media formulations contain genes Cry 1 (144 kD) and Cry 2 (66.80 kD and 55.51 kD) and Cyt1Aa (25.27). Amino acid δ-endotoxin in 500 ml scale cultivation and 3 L bioreactor show the same composition as many as 15 kinds of amino acids but the quantity of amino acids on the 3 L bioreactor scale smaller than which on 500 ml. Determination of physical factors for the increasing scale on the 40 L bioreactor using a base power per unit volume (Pg/V) still provide power value per unit volume (Pg/V) of 0.037 HP/m3 (weak level of agitation impellers), aeration requirement is 0.7 VVM with agitation speed 111.57 rpm. Cultivation at 40 L bioreactor run at a pH range from 6.5 to 7.0 where the total number of maximum cells is 10.35± 0.03 x 10 8 cfu/ml with a maximum cell growth rate of 0.48 ± 0.01 hours-1, while the number of the highest spore of 3.90±0.06 x 108 cfu/ml with a maximum rate of spore growth is 0.25 ± 0.01 hours-1. Substrate utilization efficiency at 68.21 % with LC50 values is 3.19 g/ml or 2357 IU/mg.
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Judul: Cycle Hamilton pada Graf Lengkap, Graf Regular, dan Graf 2-Connected 4-Regular Berorder Kurang dari Sepuluh
Abstrak: Suatu graf disebut graf Hamilton apabila graf tersebut memuat cycle Hamilton, yaitu cycle yang melewati setiap vertex tepat satu kali. Menentukan keberadaan cycle Hamilton pada suatu graf dapat menggunakan syarat cukup yang berupa teorema-teorema yang telah diperkenalkan sejak tahun 1950-an. Beberapa syarat cukup yang dibahas dalam karya ilmiah ini adalah syarat cukup yang berhubungan dengan graf lengkap dan graf regular. Suatu graf lengkap berorder 𝑛������ ≥ 3 dan graf r-regular berorder 𝑛������ ≤ 2𝑟������ + 1 merupakan graf Hamilton, Karena kedua graf tersebut memuat cycle Hamilton. Selanjutnya, syarat cukup tersebut digunakan untuk menentukan keberadaan cycle Hamilton pada graf 2-connected 4- regular berorder kurang dari 10.
Keyword: graf Hamilton, graf regular, graf lengkap, graf 2-connected 4-regular