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Abstrak :
Penggunaan pupuk kimia secara terus menerus dan berlebihan dapat menurunkan kualitas tanah dan dapat menurunkan hasil panen. Salah satu solusi alternatif untuk mengembalikan kesuburan tanah adalah dengan menggunakan tambahan pupuk hayati. Pupuk hayati merupakan pupuk yang berisi mikroorganisme yang memiliki kemampuan meningkatkan pertumbuhan tanaman yang disebut dengan plant growth promoting bacteria (PGPB). Penelitian ini bertujuan untuk mendapatkan bakteri dari sampel kepala udang dilanjutkan karakterisasi jenis genus bakteri dan diuji kemampuan berdasarkan karakter PGPB untuk mendapatkan isolat potensial sebagai pupuk hayati. Isolasi dilakukan dengan teknik quadrant streak dari cairan suspensi pada medium umum. Isolat bakteri yang didapatkan selanjutnya dikarakterisasi berdasarkan Cowan & Steel’s Manual for the Identification of Medical Bacteria dan diuji kemampuannya menyediakan unsur hara bagi tanaman berdasarkan karakter PGPB, yaitu kemampuan memfiksasi nitrogen, melarutkan fosfat, menghasilkan IAA dan siderofor. Kemudian setiap isolat diuji kemampuan dalam menghasilkan enzim ekstraseluler (kitinase, protease, lipase dan amilase) menggunakan medium diferensial untuk mengetahui potesi mendegradasi makromolekul yang dapat dijadikan sumber nutrien bakteri. Hasil penelitian menunjukkan bahwa diperoleh lima isolat bakteri yang diberi kode UD1 hingga UD5, diantaranya 3 isolat Gram positif (UD1, UD4, dan UD5) dan 2 isolat Gram negatif (UD2 dan UD3). Uji kemampuan PGPB terhadap kelima isolat menunjukkan 3 isolat (UD1, UD2, dan UD3) mampu memfiksasi nitrogen, 3 isolat (UD2, UD3, dan UD5) mampu melarutkan fosfat, 4 isolat (UD1, UD2, UD3, dan UD4) mampu menghasilkan IAA, dan 3 isolat (UD2, UD3, dan UD4) mampu menghasilkan siderofor. Hasil uji kemampuan menghasilkan enzim ekstraseluler menunjukkan 2 isolat (UD2 dan UD3) positif terhadap keempat jenis uji. Berdasarkan data tersebut maka bakteri hasil isolasi berpotensi untuk dijadikan agen pupuk hayati. ......The excessive use of chemical fertilizers can decrease soil quality and lead to reduced crop yields. One alternative solution to restore soil fertility is by utilizing biofertilizers. Biofertilizers contain microorganisms with the ability to enhance plant growth, known as Plant Growth Promoting Bacteria (PGPB). This study aimed to isolate bacteria from shrimp head samples, characterize the genera of bacteria, and assess their PGPB characteristics to identify potential isolates for biofertilizer application. Isolation was conducted using the quadrant streak technique from suspension fluid on a standard medium. The isolated bacteria were then characterized based on Cowan & Steel’s Manual for the Identification of Medical Bacteria and tested for their ability to provide nutrients to plants based on PGPB characteristics, including nitrogen fixation, phosphate solubilization, indole-3-acetic acid (IAA) and siderophore production. Subsequently, each isolate was tested for its ability to produce extracellular enzymes (chitinase, protease, lipase, and amylase) using differential media to determine their potential for degrading macromolecules as a bacterial nutrient source. The results showed that five bacterial isolates were obtained, including 3 Gram-positive isolates (UD1, UD4, and UD5) and 2 Gram-negative isolates (UD2 and UD3). PGPB capability tests on these isolates revealed that 3 isolates (UD1, UD2, and UD3) could fix nitrogen, 3 isolates (UD2, UD3, and UD5) could solubilize phosphate, 4 isolates (UD1, UD2, UD3, and UD4) could produce IAA, and 3 isolates (UD2, UD3, and UD4) could produce siderophores. The results of the extracellular enzyme production test indicated that 2 isolates (UD2 and UD3) tested positive for all four types of tests. Based on this data, the isolated bacteria have the potential to be used as biofertilizer agents.

Abstrak :
Telah dilakukan penelitian mengenai potensi bakteri basil indigenous sebagai plant growth promoting bacteria (PGPB). Isolat G7, G10 dan G18 yang berpotensi dalam meningkatkan pertumbuhan tanaman diisolasi dari saluran pencernaan larva lalat tentara hitam, sedangkan isolat B. siamensis LDR dengan potensi sebagai agen biokontrol diisolasi dari cocopeat. Penelitian ini dilakukan untuk untuk mengetahui karakterisasi pertumbuhan dari isolat G7, G10 dan G18, meliputi pH medium (5, 6, 7, 8, 9) dan suhu inkubasi (30, 40, 50 oC). Uji antagonisme dilakukan antara isolat G7, G10 dan G18 dengan B. siamensis LDR guna melihat kemungkinan isolat-isolat tersebut untuk disatukan dalam satu konsorsium. Uji kemampuan memfiksasi nitrogen dan memproduksi siderofor dilakukan pada isolat G7, G10, G18 dan B. siamensis LDR.  Hasil menunjukkan bahwa isolat G7, G10 dan G18 dapat tumbuh pada pH 5—9 dengan pertumbuhan optimum pada kisaran pH 7—9. Suhu optimum bagi ketiga isolat diketahui pada 40 oC. Terdapat hubungan antagonisme isolat G7, G10 dan G18 terhadap B. siamensis LDR sehingga isolat-isolat tersebut tidak dapat disatukan dalam satu konsorsium. Kemampuan memfiksasi nitrogen ditunjukkan oleh isolat G7 dan G10. Kemampuan memproduksi siderofor dimiliki oleh semua isolat, yaitu G7, G10, G18 dan juga B. siamensis LDR. Isolat G7 dan G10 yang mampu memfiksasi nitrogen serta memproduksi siderofor merupakan isolat yang lebih unggul karena memiliki karakteristik PGPB yang lebih lengkap. ......Research has been carried out on the potential of several indigenous bacili bacteria as plant growth promoting bacteria (PGPB). Isolates G7, G10 and G18 with potential to increase plant growth were isolated from the digestive tract of black soldier fly larvae, while B. siamensis LDR with potential as a biocontrol agent was isolated from cocopeat. This research was conducted to determine the growth characteristics of isolates G7, G10 and G18, including medium pH (5, 6, 7, 8, 9) and incubation temperature (30, 40, 50 oC). Antagonism test was carried out between isolates G7, G10 and G18 against B. siamensis LDR to see the possibility of these isolates to be combined in one consortium. The ability to fix nitrogen and produce siderophores were carried out on isolates G7, G10, G18 and B. siamensis LDR. The results showed that isolates G7, G10 and G18 could grow at pH 5—9 with optimal growth in the range of pH 7—9. The optimum temperature for the three isolates was at 40 oC. There was an antagonistic relationship between isolates G7, G10 and G18 towards B. siamensis LDR so these isolates could not be combined into one consortium. The ability to fix nitrogen was shown by isolates G7 and G10. The ability to produce siderophores was shown by all isolates, namely G7, G10, G18 and also B. siamensis LDR. Isolates G7 and G10 which are able to fix nitrogen and produce siderophores, were the best isolates because they have more complete characteristics as PGPB.

Abstrak :
Soil fungi occurred in the rhizosphere in many cultivated crops and wild grasses in the sandy soil were effective in enhancing the growth promoting of plant. A field experiment to study the effect of soil fungi from sandy soil as plant growth promoting fungi (PGPF). The experiment was conducted in Clinical Laboratory of Plant Pathology and glass house Faculty of Agriculture Gadjah Mada University in Yogyakarta. The sandy soil was located in Samas and Bugel Yogyakarta. The treatment was conducted in Complete Randomize Design (CRD) with 5 replications. Among 33 rhizosphere fungi tested, 26 fungal isolates were hypovirulent isolate and showed the ability as PGPF i.e. Trichoderma spp. (SB32 , CB32, SB33, CB33 and CB21). They enchanced significantly the height and dry biomass of plants compare with control.

Abstrak :
Saline soil is a common problem in coastal paddy field, especially in Indonesia. Salinity affects rice growth and the activities of soil functional microbes, including functional bacteria, which play roles in plant growth. Some of these microbes are associated with rice plants and are able to survive under saline condition. The presence of functional microbes is also important to improve soil quality. Nitrogen and phosphate are essential soil nutrients and is available in soil due to the activities of nitrogen-fixing bacteria and free-living plant-associated bacteria. The objective of the present study was to obtain nitrogen-fixing, phosphate solubilizing and Indole Acetic Acid  (IAA)-producing bacteria that are able to survive and promote the growth of rice under saline conditions. From rice and peanut rhizosphere, Ca-phosphate (Ca-P) solubilizing and nitrogen-fixing bacteria were isolated separately using specific media. Then, the Ca-P solubilizing ability, phosphomonoesterase activity and IAA-producing ability were quantitatively examined. Based on the abilities, 20 strains were selected and identified as Burkholderia cepacia-complex, Burkholderia anthina, Burkholderia cenocepacia, Bacillus cereus-complex (three strains), Achromobacter spanius, Azospirillum sp. (four strains), Azotobacter sp. (three strains), Rhizobium leguminosarum, Rhizobium sp. (two strains), and Pseudomonas sp. (three strains). The inoculation of several single strains or the mixture of the selected strains promoted the growth of rice under saline conditions. These inoculants could be potential as biofertilizer in saline paddy fields.

Abstrak :
Bacteria in agrobiology : stress management, covers the major aspects on PGPR in amelioration of both abiotic and biotic stresses. PGPR mediated in priming of plant defense reactions, nutrient availability and management in saline and cold environment, hormonal signaling, ACC deaminase and its role in ethylene regulation under harsh conditions are suitably described.