UJI POTENSI BAKTERI PELARUT FOSFAT: TOLERANSI TERHADAP KEMASAMAN ALUMINIUM SULFAT ATAU KEMAMPUAN MENYINTESIS HORMON IAA

Nitrogen, phosphate, and potassium are elements that are less available in most farmlands and swamps. farmers provide additional fertilizer for the sustainability of agriculture. The three macro elements are used in plants in larger numbers than other important elements (Idiyah, et al., 1995). One of the three elements that has a large influence on plant production is phosphate. Phosphate plays an important role in the process of cell division, flower formation, fruit, seeds, and as an energy transfer for example ATP and ADP (Hardjowigeno, 2015). Phosphate is seen as a regulatory element or determinant of biological productivity (Notohadiprawiro, 1999). Lack of P in the soil is one of the factors that occurs binding (fixation) by Al on acid soils or by Ca on alkaline soils (Hardjowigeno, 2015) so that plants are unable to absorb P in the bound form. Nutrient deficiency in soil can be improved by the addition of biological fertilizers (Haryono, 2013). The use of biological fertilizers can increase the efficiency of inorganic fertilizers and plant productivity significantly (Ekin, 2010). Biofertilizer is an organic fertilizer consisting of various microbial consortia. Research on the exploration and potential of phosphate solvent bacteria is expected to be an alternative agent for phosphate sources for plants. Exploration of multiple functions in bacteria needs to be done to obtain the ability of bacteria to synthesize fitohormones to increase the role and efficiency of these bacteria as well as phosphate Soluble. This research uses a descriptive design using soil samples from reclaimed land from former limestone mine at PT. Semen Indonesia, the media used uses Pikovkaya's selective media. The results of this study obtained three positive phosphate solvent bacterial isolates capable of dissolving phosphate with different abilities and were able to synthesize IAA hormones, and tolerated acidic environments. The highest soluble phosphate was recorded in P2S2 isolates with a potential increase of 13.99% and 34 ppm dissolved phosphate. All bacterial isolates have the ability to synthesize IAA fitohormones with different levels, the highest IAA was recorded in P2S2 isolates of 0.5695 ppm. The bacterial isolate was able to synthesize fitohormone because of the presence of L-Trythopan as the main precursor of IAA formatio