Gamma Irradiation and Autoclave Sterilization Peat and Compost as the Carrier for Rhizobial Inoculant Production

Abstract

Rhizobium is a biofertilizer for leguminous crops. To formulate this form of fertilizer, the suitable sterilization processes of carrier are important. Therefore, the aim of this research was to elucidate the process of gamma irradiation and autoclaving on peat and compost based carriers for rhizobial inoculant production. Carriers with 10% moisture content packing in polyethylene bag could be efficiently sterilized by irradiation at 10-20 kGy, or by autoclaving with tyndallization approach (autoclaving two times in a row at 121ºC for 60 min, with waiting period of 18 hours after each time of autoclaving). The number of Bradyrhizobium sp. PRC008 was in the range of 10 8 -10 9 cfu/g in both irradiated and autoclaved peat after 6 months storage. However, the numbers of bradyrhizobial cell were reduced in compost sterilized by both methods after one month storage. These results indicated that carrier material had an important influence on inoculant quality, while sterilization processes using gamma irradiation and autoclaving with tyndallization approach could be used for efficient rhizobial inoculant production with peat based carrier.

PERBAIKAN KUALITAS BAHAN PEMBAWA Rhizobium dan FUNGI PELARUT FOSFAT MELALUI STERILISASI SINAR GAMMA Co-60 DAN PENGARUHNYA TERHADAP PERTUMBUHAN DAN PRODUKSI KEDELAI (Glycine max L.)

“…Namun metode ini dapat merubah karakter kimia dan fisik bahan pembawa yang pada akhirnya akan berpengaruh pada populasi mikrob di dalamnya. Iradiasi sinar gamma Co-60 lebih mudah, dapat digunakan dalam skala besar, dan dapat memperpanjang masa simpan [19,20]. Tujuan penelitian ini adalah untuk mempelajari pengaruh sterilisasi menggunakan sinar gamma Co-60 dan autoclave terhadap sifatsifat bahan pembawa, populasi mikrob fungsional, dan pengaruhnya terhadap pertumbuhan dan produksi kedelai varietas Mutiara 3.…”

The viability of Phanerochaete chrysosporium inoculant in gamma-irradiated-compost carrier and its biosorption efficiencies for Cd (II) and Cr (VI)

“…This showed that the heat from water vapor by an autoclave unable to penetrate the carrier matrix and thus unable to eliminate bacterial growth. This also occurred in another study which employed autoclaving with tyndallization approach on peat and compost [5]. However, different results occurred in the carrier in the form of peat moss, the mixture of peat moss plus vermiculite, wheat bran, rice husk, clay, and sodium alginate, sterilized by autoclave as well, that no contaminants have been detected in all the sterilized carriers [14].…”

“…The gammairradiation sterilization method at a dose of 25 kGy is able to sterilize the carrier material until the microorganism is not detected. Gamma ray is an effective method for sterilization, since the ionizing radiation interacts directly with charged particles such as DNA, and results in doublestrand break [5]. In contrast to sterilization with gammairradiation, autoclave sterilization left microorganisms, especially bacteria, with different concentrations according to the carrier composition.…”

“…However, autoclave sterilization causes some materials to change their properties and produce a toxic substance to some bacterial strains [7]. Another sterilization method is gamma irradiation [5,7,8], which has the advantage of not changing the carrier characteristics. The 25 kGy dosage has been widely used for sterilization of compost-based carriers capable of killing microorganisms both bacteria and fungi [9].…”

“…A good carrier should be insoluble, non-toxic, both for the immobilized material and the environment, easily accessible, inexpensive, stable and suitable for regeneration [4]. Compost as a carrier has been used in biofertilizer applications, for example by using agents of rhizobial bacteria [5] dan arbuscular mycorrhizal fungi [6].…”