Pengaruh Umpan Tambahan pada Akumulasi Polihidroksibutirat (PHB) oleh Bacillus cereus IFO 13690 Menggunakan Substrat Tapioka

https://doi.org/10.22146/agritech.9732

Margono Margono(1*), Rochmadi Rochmadi(2), Siti Syamsiah(3), Muhammad Nur Cahyanto(4)

(1) Jurusan Teknik Kimia, Fakultas Teknik, Universitas Sebelas Maret, Jl. Ir. Sutami 36A, Surakarta
(2) Jurusan Teknik Kimia, Fakultas Teknik, Universitas Gadjah Mada, Jl. Teknika Utara, Yogyakarta 55281
(3) Jurusan Teknik Kimia, Fakultas Teknik, Universitas Gadjah Mada, Jl. Teknika Utara, Yogyakarta 55281
(4) Jurusan Teknologi Pangan dan Hasil Pertanian, Fakultas Teknologi Pertanian, Universitas Gadjah Mada, Jl. Flora, Bulaksumur, Yogyakarta 55281
(*) Corresponding Author

Abstract


Bacillus cereus IFO 13690 is Gram positive bacteria that produces polyhydroxybutyrate (PHB). It has amylolytic characteristic that can be cultured using cassava starch. This research reported the ability of B. cereus IFO 13690 on accumulating PHB and the effects of starch and ammonium feeding on cell and PHB productivity. Batch process was conducted with initial starch of 18 g/l, medium pH of 5.6 and medium temperature of 30 oC. Fed batch process was conducted in the same conditions of the optimum batch process with feeding of 2.1 l/hat 7th ­7.65thhours of exponential growth and 1.86 l/hat 10th­10.8thhours of exponential growth. The feeding compositions were starch of 70 g/l and am­ monium sulfate of 20 g/l. The results of batch process showed that the highest accumulation of PHB was achieved with initial ammonium of 1.20 g/l and dissolved oxygen of 5 % air saturation. The highest PHB accumulation of 0.13 g/l was achieved after 29 hours of fermentation. It was similar to 0.005 g/l.h productivity and the PHB content was 2.42%. The productivity of cell and PHB in fed batch process was double compared to the batch process, i.e. 0.39 g/l.h and0.01 g/l.h, respectively. The PHB content in cell dry weight was relatively higher in the fed batch compared to batch process, i.e. 2.50 %.

ABSTRAK

Bacillus cereus IFO 13690 adalah bakteri Gram positif penghasil polihidroksibutirat(PHB) yang bersifat amilolitik sehingga dapat dikulturkan dalam substrat pati. Penelitian ini dimaksudkan untuk melaporkan kemampuan B. cereus IFO 13690 dalam mengakumulasi PHB pada proses batch dan pengaruh penambahan pati serta amonium terhadap produktivitas sel dan PHB pada proses fed batch. Percobaan proses batch dilaksanakan pada konsentrasi pati awal 18 g/l, pH medium 5,6 dan suhu medium 30 oC. Percobaan proses fedbatch dilaksanakan seperti pada proses batch opti­ mum kemudian ditambahkan medium umpan pada saat pertumbuhan eksponensial, yaitu 2,1 l/jam pada saat pertum­ buhan eksponensial berlangsung pada jam ke­7­7,65 dan 1,86 l/jam pada saat pertumbuhan eksponensial berlangsung pada jam ke­10­10,8. Komposisi umpan terdiri dari pati 70 g/l dan amonium sulfat 20 g/l. Hasil percobaan proses batch menunjukkan bahwa akumulasi PHB paling tinggi dicapai pada percobaan dengan konsentrasi amonium awal 1,20 g/l dan konsentrasi oksigen terlarut 5 % jenuh. Akumulasi PHB tertinggi mencapai 0,13 g/l dalam waktu fermentasi 29 jam. Produksi tersebut setara dengan produktivitas 0,005 g/l.jam dan kadar PHB dalam sel sebesar 2,42 %. Produktivi­ tas sel dan PHB pada proses fedbatch bisa menjadi 2 kali lebih besar dibandingkan dengan proses batch, yaitu 0,39 g/l. jam dan 0,01 g/l.jam. Kadar PHB dalam sel pada proses fedbatch sedikit lebih tinggi dibandingkan pada proses batch, yaitu 2,50 %.


Keywords


Polyhydroxybutyrate; Bacillus cereus; batch; fed batch; tapioca

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DOI: https://doi.org/10.22146/agritech.9732

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Agritech (print ISSN 0216-0455; online ISSN 2527-3825) is published by Faculty of Agricultural Technology, Universitas Gadjah Mada in colaboration with Indonesian Association of Food Technologies.


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