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The potential of phosphate solubilizing bacteria/PSB (Bacillus megaterium, B. pantothenticus, Chromobacterium lividum and Klebsiella aerogenes) were used as biofertilizer to increase the fresh leaf production of green mustard (Brasica caventis Oed.). An experiment was conducted at green house condition. The experiment were used 18 treatments such as single isolate of potential PSB (A,B,C,D), inoculants contain two isolates of potential PSB (E,F,G,H,I,J), inoculants contain three isolates of potential PSB (K, L, M, N), inoculants contain four isolate of potential PSB (O), chemistry fertilizer (P = control 1), organic fertilizer (Q = control 2), and without fertilizer (R = control 3). The treatments were arranged in Completely Randomized Design (CRD) with 5 replications. The result showed that the inoculants of potential PSB increased the fresh plant production of green mustard. The mix of four isolates of potential PSB (inoculants O) was the best to increase the fresh plant production of green mustard until 32.87% than other PSB inoculants, 207.84% than control 1,217.23% than control 2, and 930.60% than control 3. PENDAHULUANFosfor merupakan unsur esensial kedua setelah N yang berperan penting dalam proses pertumbuhan tanaman, serta metabolisme dan proses mikrobiologi tanah. Fosfor dalam tanah, 70% berada dalam keadaan tidak larut (Foth, 1990), hal tersebut sangat berpengaruh terhadap serapan hara lain, khususnya pada saat unsur P menjadi faktor pembatas (Foth dan Ellis, 1988). Ketersediaan unsur P dalam tanah ternyata sangat bergantung pada aktivitas mikroorganisme dalam tanah (Amarisi dan Olsen, 1973), seperti adanya aktivitas dari kelompok bakteri pelarut fosfat/BPF (Rao, 1982).Bakteri pelarut fosfat (BPF) merupakan bakteri tanah yang bersifat non patogen dan termasuk dalam katagori bakteri pemacu pertumbuhan tanaman. Bakteri tersebut menghasilkan vitamin dan fitohormon yang dapat memperbaiki pertumbuhan akar tanaman dan meningkatkan serapan hara (Glick, 1995). Bakteri pelarut fosfat merupakan satu-satunya kelompok bakteri yang dapat melarutkan P yang terjerap permukaan oksida-oksida besi dan almunium sebagai senyawa Fe-P dan Al-P (Hartono, 2000). Bakteri tersebut berperan juga dalam transfer energi, penyusunan protein, koenzim, asam nukleat dan senyawa-senyawa metabolik lainnya yang dapat menambah aktivitas penyerapan P pada tumbuhan yang kekurangan P (Rao, 1994).Hasil penggalian keberadaan dan potensi mikroba tanah di daerah Kebun Biologi Wamena (KBW) menghasilkan 4 jenis bakteri potensial sebagai pupuk biologi, yaitu Bacillus megaterium, B. pantotheticus, Chromobacterium lividum, dan Klebsiella aerogenes (Widawati dkk., 2005). Isolatisolat BPF tersebut adalah bakteri indigenus KBW dengan efektivitas teruji secara laboratoris dan skala rumah kaca pada tanaman legum tahunan seperti kaliandra (Latupapua dan Widawati, 2001), legum tumbuh cepat seperti kacang tanah (Widawati dkk.,2001; Rahayu dkk., 2001), tanaman obat tradisional seperti kumis kucing (Widawati dkk., 2002), dan temu lawak (Sugiharto dan ...

This study aimed to determine the extent of phosphate solubilizing bacteria resistant to salinity and still be able to provide P for paddy plant. Research using completely randomized design with fertilizer treatments: (1) 0% (0 grams / 7 kg soil), (2) 0.1% (7 grams / 7 kg soil), (3) 0.2% (14 g / 7 kg soil), (4) 0.3% (21 g / 7 kg soil), and (5) 0 , 4% (28 g / 7 kg soil). Thirty and one hundred days after transplanting (DAT), and then measured plant height, number of tillers, number and dry weight of whole grain paddy. The results showed that 0,1 % (7 gram/7 kg tanah) salinity is very good for the growth, activity and effectiveness of phosphate solubilizing bacteria and production of paddy, but 0.4% salinity (28 gr/7kg land) is still safe on the growth, activity and effectiveness of phosphate solubilizing bacteria (Pseudomonas fluorescens, Bacillus thuringiensis, B. megaterium, Nocardia mesentrica, Aerobacter aerogenes, spirillum lipoferum and Azotobacter indicus) as biofertilizer or growth promoting rhizobacteria on growth and production of paddy.Key words: Salinity, Phosphate solubilizing bacteria, Paddy INTRODUCTIONSalinity is the dissolved salt content which has units of milligrams per liter (mg / L) or decisiemens per meter (dS/m), with salinity values around 30 dS / m for sea water and 0.3 dS / m for ordinary water (Water, 2007). High salinity is the cause of death of bacteria and plants, especially paddy (Widawati, 2012). As an attempt for the survival of paddy plants, then had to isolate phosphate solubilizing bacteria from saline environments (coastal ecosystems). Bacteria are expected to help provide an element of P for growth and production of paddy in the high saline levels, especially the breeding and the beginning vegetative growth. Phosphor element is the main element (essential) needed in the metabolic processes of plants and plants just absorb it in the orthophosphate ions (H 2 PO 4 -and HPO 4 -)

Indole acetic acid (IAA) is a phytohormone which one of the important compounds for plant growth and development, affecting as inducing cell elongation, cell enlargement and cell division. IAA synthesized both in the plants and microorganisms. For microorganisms, production of phytohormone IAA is one of the essential criteria for plant growth promotion. The aim of the present study was to isolate and screen IAA producing bacteria from peat land area in West Kalimantan and optimized some culture conditions for maximum IAA production. The production of IAA was determined in TSB and YEMB liquid medium and the optimization of IAA production in culture media was carried out at different of incubation time, L-Tryptophan concentrations, carbon and nitrogen sources, pH and temperature. The result revealed that maximum IAA production of Bacillus siamensis was achieved at 96 hours of incubation. The YEMB medium supplemented with 250 ppm of tryptophan was obtained as the best medium for IAA production (9.89 μg/ml). This bacterium produced optimum levels of IAA in the presence of sucrose (10.23 μg/ml) and tryptone (16.61 μg/ml) as carbon and nitrogen sources respectively. In the physical parameters, the maximum production of IAA was recorded at T 35°C (8.42 μg/ml) and a pH of 8.0 (13.29 μg/ml).

ABSTRAK. Beberapa mikrob yang bersifat nonpatogenik dan nonsimbiotik yang efektif menambat nitrogen dari udara serta mampu melarutkan P terikat pada Ca, Al, dan Fe dalam tanah, dapat hidup dalam berbagai ekosistem di alam. Sebagian bakteri tersebut dapat diisolasi dari daerah perakaran tanaman hortikultura. Penelitian bertujuan mengetahui peran Azospirillum sp. yang potensial sebagai pendorong pertumbuhan tanaman pada ekosistem pantai dan kondisi lingkungan yang ekstrim. Pengujian terhadap isolat bakteri yang dikumpulkan dari berbagai kondisi ekosistem dilaksanakan di Laboratorium Ekofisiologi, Pusat Penelitian Biologi, LIPI, Bogor dari Bulan Januari sampai dengan Desember 2011. Sebanyak 34 isolat Azospirillum sp. diuji dengan berbagai metode, yaitu (1) uji kualitatif kemampuan isolat Azospirillum sp.  dalam menambat (fiksasi) nitrogen dan kemampuan hidup pada media Okon padat yang mengandung NaCl, (2) uji kualitatif kemampuan isolat Azospirillum sp. dalam melarutkan P terikat pada  Ca3(PO4)2 dalam media  Pikovskaya padat dan indeks efisiensi pelarutan fosfat,  (3) uji kualitatif kemampuan isolat Azospirillum sp. dalam melarutkan P terikat pada media  Pikovskaya cair  dan aktivitas enzim PME-ase asam dan basa, serta kondisi pH selama inkubasi 7 hari pada kultur murni (pH asal= 7), dan (4) analisis kemampuan Azospirillum sp. dalam memproduksi indole acetic acid (IAA).  Hasil penelitian menunjukkan bahwa: (1) semua isolat bakteri yang diuji mampu menambat nitrogen dalam media Okon padat,  (2) isolat B2, B4, B6, B12,  B14, PS2, dan FR13 mampu melarutkan P dari Ca3(PO4)2 dalam medium Pikovskaya padat dengan masing-masing indeks efisiensi pelarutan sebesar  120, 160, 140, 100, 110, 120, dan 100,  (3) isolat B1, B2, B3, B4, B6, B14, B17, PS1, PS2, PS3, FR1, FR5, FR7, FR8, FR10, FR12, dan FR13 mampu tumbuh dalam medium Okon dengan kandungan NaCl sebesar 0, 2, 4, atau 6%, (4)  konsentrasi tertinggi P terlarut dihasilkan oleh isolat B4 (5,80 mg/l), B6 (5,84 mg/l), dan PS2 (5,45 mg/l) dengan PME-ase sebesar 0,58 u m/l, 0,58 u m/l, 0,57 u m/l (asam), 0,52 mg/l, 0,50 mg/l, 0,48 mg/l (basa), dan dengan  pH : 4,20, 4,30, dan 4,22,  dan (5) isolat B4 dan B6 yang diisolasi dari pertanaman padi di pantai Rambut Siwi, Bali, mampu memproduksi IAA tertinggi, yaitu masing-masing sebesar 0,6749 dan 0,4694 ppm pada hari pertama setelah perlakuan. Berdasarkan hasil penelitian ini terbukti bahwa isolat Azospirillum sp. berpotensi sebagai plant growth promoter  untuk ekosistem di daerah pesisir atau pantai. Bakteri tersebut sangat penting untuk pengkayaan nutrisi pada lahan di daerah dataran rendah atau pantai dalam rangka pengembangan tanaman termasuk komoditas hortikultura.<br /><br />ABSTRACT. Widawati, S and Muharam, A 2012. The Laboratory  Test of  Azospirillum sp. Isolated  from Several  Ecosystems. Microbes that are nonpathogenic  and nonsymbiotic bacteria which are effectively fixed up nitrogen from air, and are able to dissolve phosphated bounded on Ca, Al, and Fe in soil, are able to growth in different ecosystems in nature. Some of the bacterial species can be isolated from rizosphere of horticultural crops. The research was aimed to determine the potential role of Azospirillum sp.  as a plant growth promoter in coastal ecosystem and extremely environmental conditions. The laboratory test of Azospirillum sp. isolated from several ecosystems was carried out in the Ecophysiology Laboratory, Research Center for Biology, Indonesian Institute of Sciences, Bogor from January until December 2011. Thirty-four isolates of Azospirillum sp. (B1 to B17;PS1 to PS3; FR1 to FR 14) were investigated with some methods i.e. (1) the qualitative test of the capability of Azospirillum sp. to fix up nitrogen in solid Okon medium containing NaCl, (2) the qualitative test of the capability of Azospirillum sp. in dissolving bounded P in solid Pikovskaya medium and phosphate dissolution efficiency index,  (3) the qualitative test of the capability of Azospirillum sp. in dissolving bounded P in liquid Pikovskaya medium and the activity of acid and base PME-ase, and pH condition after 7 days incubation in pure media, and (4) analysis of the capability of Azospirillum sp. in producing indole acetic acid (IAA).  The results pointed out that : (1) all tested isolates of Azospirillum sp. were  capable to fix up nitrogen in solid Okon medium, (2) isolates of B2, B4, B6, B12,  B14, PS2, and FR13 were capable to solubilize P on Ca3(PO4)2 in solid Pikovskaya medium with its efficiency of  120, 160, 140, 100, 110, 120, and 100, respectively, (3) isolates of B1, B2, B3, B4, B6, B14, B17, PS1, PS2, PS3, FR1, FR5, FR7, FR8, FR10, FR12, and FR13 were able to grow in Okon medium with 0, 2, 4, or 6% of NaCl doses, (4) the highest concentrations of solubilized P was resulted by isolates B4 (5.80 mg/l), B6 (5.84 mg/l), and PS2 (5.45 mg/l) with PME-ase i.e. 0.58 u m/l, 0.58 u m/l, 0.57 u m/l (acid), 0.52 mg/l, 0.50 mg/l, 0.48 mg/l (base), and with pH : 4.20, 4.30, and 4.22, and (5) isolates of B4 and B6 isolated from rice field at Rambut Siwi beach, Bali, were capable to produce highest IAA hormone i.e. 0.6749 and 0.4694 ppm respectively  on the first day after the treatment. Based on the result of this experiment it can be concluded that Azospirillum sp. is a potential plant growth promoting Rhizobacteria for coastal ecosystem. The bacterial species is very important to enrich coastal areas for crop cultivation, including horticulture.<br /><br />

The isolation, identification and population of soil microbes from rizosphere at WBiG had been done in the Soil Laboratories Microbiology,

Phosphate solubilizing bacteria (PSB) were collected from plant rhizosphere at Cikaniki (1100 m asl.), soil at Botol Mountain (1000, 1500, and 1800 m asl.), and Ciptarasa (600, 1000, and 1500 m asl.), area at Gunung Halimun National Park (GHNP). The soil ware collected randomly from 3 areas and taken from 0-15 cm depth in the plants rhizosphere at Cikaniki and forest floor soil in Gunung Botol and Ciptarasa. The result showed that the difference of elevation area, soil pH, forest vegetation, and microbial habitat (rhizosphere and forest floor) were not the inhabitation factors of the biodiversity of PSB and their ability to solubilize insoluble phosphate, but the inhabitation factors on the growth of the PSB population. The highest population of PSB at GHNP was founded in the plant rhizosphere of Altingia exelsa Norona and Schima wallichii (Dc.) Korth (10 7 sel/g soil) at Cikaniki and in the forest floor soil (10 8 sel/g soil) at Botol Mountain (1000 m asl.). Pseudomonas sp., Bacillus sp., Bacillus megaterium, and Chromobacterium sp. dominated Cikaniki, Botol Mountain and Ciptarasa area. Those isolates could solubilize insoluble phosphate on solid Pikovskaya medium with the range of diameter is 1.5-2.5 cm.

A study was undertaken to investigate the occurrence of phosphate solubilizing bacteria (PSB) and nitrogen-fixing bacteria (NFB) from soil samples of Wamena Biological Garden (WbiG). Eleven soil samples were collected randomly to estimate microbial population which used plate count method. The result showed that the microbial population ranged from 5.0x10 3-7.5x10 6 cells of bacteria/gram of soil and 5.0x10 3-1.5x10 7 cells of bacteria/gram of soil for PSB and NFB respectively. There were 17 isolates which have been identified till genus and species. The isolated microorganism were identified as PSB i.e.