<![CDATA[ABSTRAKPada penelitian ini, sistem kultur suspensi sel wortel (Daucus carota L.) digunakan sebagai model untuk mengetahui pengaruh variasi pH terhadap pertumbuhan biomassa sel serta laju konsumsi substrat amonium dalam medium. Kalus ditumbuhkan selama 24 hari dalam sistem batch pada medium cair MS (Murashige dan Skoog) dengan penambahan 4,5 x 10-6 M kinetin dan 4,5 x 10-6 M 2,4-D serta kondisi pH awal medium berbeda yaitu pH 4,5; 5,8 dan 7,5. Perubahan pH medium diamati setiap 3 hari sekali disertai dengan pengukuran berat biomassa sel dan kandungan amonium dalam medium. Hasil pengamatan menunjukkan bahwa laju pertumbuhan spesifik biomassa sel paling tinggi terjadi pada kultur dengan kondisi pH awal medium 4,5 yaitu 0,08 hari-1 sedangkan paling rendah pada kondisi pH awal medium 5,8 (kontrol) yaitu 0,02 hari-1. Variasi pH awal medium menyebabkan perubahan dan fluktuasi nilai pH dalam medium sehingga mempengaruhi tingkat penyerapan substrat amonium dalam medium. Laju konsumsi amonium tertinggi terjadi pada kultur perlakuan pH awal medium 4,5 yaitu sebesar 0,088 mM/hari. Penggunaan amonium untuk pertumbuhan biomassa juga paling efektif pada kultur dengan kondisi pH awal medium 4,5 dengan nilai perolehan biomassa per substrat amonium mencapai 0,875 g sel/mM amonium. Penelitian ini dapat memberikan gambaran mekanisme dan efisiensi penyerapan media pada medium pertumbuhan sehingga dapat diterapkan untuk pengendalian sistem produksi terutama sistem bioreaktor. Kata kunci : amonium; batch; Daucus carota L.; pH; pertumbuhan sel ABSTRACT In this experiment, a carrot (Daucus carota L.) cell suspension system was used as a model to determine the effect of pH variations on cell biomass growth and the rate of consumption of ammonium substrates in the medium. Callus was grown for 24 days in a batch system on MS liquid medium (Murashige and Skoog) with the addition of 4.5 x 10-6 M kinetin and 4.5 x 10-6 M 2,4-D and the initial pH of the medium was different, namely pH 4,5; 5.8; and 7.5. Changes in the medium's pH were observed every three days, accompanied by cell biomass weight measurements and ammonium content in the medium. The observations showed that the highest specific cell growth rate occurred in cultures with medium pH initial conditions of 4.5, 0.08 days-1, while the lowest at medium pH conditions of 5.8 (control), 0.02 days-1. Variations in the initial pH of the medium cause changes and fluctuations in the medium's pH value so that it affects the rate of absorption of ammonium substrates in the medium. The highest ammonium consumption rate occurred in the culture medium initial pH treatment equal to 0.088 mM/day. The use of ammonium for biomass growth is most effective in cultures with an initial pH medium condition of 4.5 with the acquisition value of biomass per ammonium substrate, reaching 0.875 g cells/mM ammonium. This research can provide an overview of the mechanism and efficiency of media absorption in the growth medium to be applied to control production systems, especially in bioreactor systems. ]]>
