PENGARUH SUMBER KARBON DALAM BIOAKTIVASI BATUAN FOSFAT MENGGUNAKAN Aspergillus niger

Abstract

Bioactivation of phosphate rock (PR) using
phosphate solubilizing microorganism is possibly
able to increase effectivity of PR to supply
phosphorus (P) for plant. The research was aimed
to study effect of carbon source to increase
solubility of RP that was activated by Aspergillus
niger. Christmas Island phosphate rock was used
as P source. Kind of carbon sources included
glucose; cane molasses; organic material consists
of tapioca waste, rice bran, and starch (BOC); and
humic substance extracted from peat using 0.5 M
NaOH. Inoculum of A. niger was prepared by
Laboratory of Microbiology of Agriculture
Faculty, Gadjah Mada University. Amount of
soluble P were determined using spectrofotometry
method, while the amount of A. niger were
determined using plate count method. Result of
the study showed that the kind and the amount of
the carbon source influenced the PR solubility that
was activated by A. niger. Glucose, cane
molasses, BOC, and humic substance increased
water-dissolved P i.e. 552.0%, 831.4%, 919.3%,
and 491.0%, respectively, while 2% citric aciddissolved
P reached 68.3%, 67.8%, 65.9%, and -
31.2%, respectively. Addition of cane molasses up
to 20% and humic substance up to 10% decreased
the solubility of PR in 2% citric acid.