Pembuatan starter (startmik), pemeliharaan mikroba dalam starter & pemantauan viabilitas & aktivitas mikroba dalam pupuk organik hayati sebagai upaya mempertahankan kualitas

Laboratory studies were conducted to study the beneficial properties of plant growth-promoting rhizobacterial (PGPR) strains in relation to the qualities of liquid organic biofertilizer (LOB). Firstly PGPR strains were grown on fermentor as starter, then it has been used for production of LOB. The viabilities of PGPR strains were also tested under frees drying method, glycerol preservation and under refrigerator. Finaly, the Indol Acetic Acid containing LOB was measured by HPLC. The results showed that growing of the mixed PGPRS as starter under fermentor were slow, needed about two weeks incubation. The viabilities of pure cultures under different preservation method were in general very good. After 1 year preservation under liquid drying, the viabilities were about 108 CFU and under refrigerator (4-10oC), after 5 months were above 108 CFU. The concentration of IAA produced in LOB ranged from 3 – 55 ppm. The highest IAA concentration was in the LOB after 5 months preservation, followed by 1 year, 1 week and fresh LOB