| Summary: | Indole Acetic Acid (IAA) is a great plant hormone for orchid growth and
development. The existence of orchids that grow naturally indicate there are a
number of plant hormone in their environment. Hormone can be derived from
bacteria in soil rhizoplane. The populations terrestrial orchid Pecteilis susannae have
been rare. Therefore, this study aim to obtain IAA-producing bacteria from
rhizoplane of terrestrial orchid P. susannae, to select bacterial isolates with the
highest ability of IAA production, as well as studying effect of tryptophan on
bacterial IAA production. Bacteria was isolated from rhizoplane of terrestrial orchid
P. susannae at the Hutan Adat Wonosadi, DIY. Selection of capability of IAA
producing performed on Nutrient Broth medium suplemented with 200μg/ml
tryptophan. The test of selected isolates on growth and IAA production performed on
synthetic medium Czapek Dox Liquid Modified which supplemented with 200μg/ml
tryptophan. Test the influence of tryptophan on IAA production of selected isolates
were performed on Nutrient Broth medium supplemented with 0, 50 and 100μg/ml
tryptophan as well as on Czapek Dox Liquid Modified medium supplemented with 0,
50, 100 and 200μg/ml tryptophan. Nearly 81% of the total population of bacteria
found on the ground orchid rhizoplane P.susannae capable to produce IAA. The
highest IAA producing bacteria is BRAWI-9 isolates which requires tryptophan to
produce the highest IAA. The characteristics of BRAWI-9 bacteria isolates have
similar to the family Enterobacteriaceae, Enterobacter genera. Up to concentration
200μg/ml of tryptophan influenced an increase on IAA production significantly by
selected bacterial isolates.
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