Hasil Pencarian  ::  Simpan CSV :: Kembali

"Microbial communities usually have mixed populations, only in uniqueenvironmental situations do microorganisms live entirely alone. Thus many types of interactions are possible among the members of an ecosystem?s community. In general, the constant association of different organisms in an ecosystem is referred to as symbiosis, with the associates being called symbionts. One type of a symbiosis is antagonism. Antagonism is a symbiotic relationship in whichone population of microorganisms has a harmful effect on the growth of another microbial population (Batzing 2002: 696). A number of microorganisms (bacteria, yeasts, fungi) which effectivelycontrol postharvest pathogens have been identified as antagonists (Mari and Guizzardi 1998:60). A variety of microbial antagonists were reported to control several different pathogens on various fruits. The organism that suppresses the pest or pathogen is referred to as the biological control agent (BCA) (Pal & Mcspadden Gardener 2006: 1). Biological control may in simple terms be defined as the use of one living organism to control another (Druvefors 2004: 4).Often antagonists are isolated on the surface of plants; this natural presence makes them more likely to succeed because of their colonization ability and environmental adaptation (Mari and Guizzardi 1998:60). The use of yeasts as antagonists appears to be quite promising, although the mechanism has not yet been fully elucidated. Some antagonist yeasts have been reported as biocontrol agent of fungal pathogen on fruits. Zhao et al. (2008: 115--116) reported that tomato fruit treated with Pichia guillermondii had an infection rate of 25% which was caused by Rhizopus nigricans, which wassignificantly lower than the control (41.67%). Kalogiannis et al. (2006: 72) reported that Rhodotorula glutinis Y-44 significantly reduced disease incidence caused by Botrytis cinerea on tomato by 52%, compared to the untreated control. Zhang et al. (2004: 84) reported that the application of Cryptococcus laurentii resulted in low average decay incidence caused by B. cinerea in fruit by 7.1%, compared with 40% in the water-treated control fruit. University of Indonesia Culture Collection (UICC) collected epiphytic yeasts from plant samples of Cibodas Botanical Garden, and moulds from decayed tomatoes and infected plants. The ability of the epiphytic yeasts as biocontrol agents against tomato spoilage-causing moulds has not beenreported. This study consists of two parts. Part 1 is The Antagonistic Ability of Epiphytic Yeasts of Cibodas Botanical Garden on Tomato Plant Infected-Causing Moulds. Part 2 is The Potential of Candida sp. UICC Y-328 as a Biocontrol Agent of Aspergillus ochraceus on Postharvest Tomatoes.The purposes of this study were to investigate the ability of six species of epiphytic yeasts in inhibiting the growth of tomato plant infected-causing moulds, and the potential of Candida sp. UICC Y-328 as a biocontrol agent in reducing postharvest tomato spoilage caused by Asp. ochraceus. The media used for growing the yeasts was Yeast Malt Agar (YMA), and maintenance for fungi was Potato Dextose Agar (PDA). The media used for antagonistic test were PDA and Potato Dextrose Broth (PDB). Antagonistic test by strip method was carried out by using the concentrations of yeast cells at (0.7--4.45) x 108 CFU/ml, and Asp. ochraceus at (7.0--8.1) x 107 CFU/ml, Asp. terreus Thom at (7.7--8.6) x 107 CFU/ml andDrechslera sp. at (0.45--3.5) x 105 CFU/ml. The yeast cells were inoculated 4 hours earlier before inoculation of mould spores on PDA in Petri dishes. Results showed that Candida sp. UICC Y-328 has highest percentage of colony reduction of Asp. ochraceus (56.45%), followed by Metschnikowia reukaufii UICC Y-351 on reducing colonies of Asp. terreus and Drechslera sp. (25.42% and 51.28%, respectively) during 6-day incubation. Antagonistic test by co-culture method was carried out by using the concentrations of yeast cells at (0.7--4.45) x 108 CFU/ml, and Asp. ochraceus at (6.0--8.6) x 107 CFU/ml, Asp. terreus at (4.6--9.5) x 107 CFU/ml. The yeast cells were inoculated 8 hours earlier before inoculation of mould spores on PDB. Results showed that Candida sp. UICC Y-328 reduced the size of conidial heads(5.52%) and hyphae (8.29%) of Asp. ochraceus, at 3-day incubation.Cryptococcus laurentii UICC Y-379 reduced the size of conidial heads and hyphae of Asp. ochraceus (15.07% and 11.60% respectively) and Asp.terreus (12.35% and 24.47% respectively) at 3-day incubation. Antagonistic test by slide culture method showed that the yeast cells of four strains (Candida rancensis UICC Y-326, Cr. laurentii UICC Y-319, Cr. laurentii UICC Y-379,and M. reukaufii UICC Y-351) attached to hyphae of Drechslera sp. after 3- and 4-day incubation.Cells of Candida sp. UICC Y-328 attached to hyphae of Drechslera sp. after 4-day incubation. Cells of Cr. laurentii UICC Y-385 was not able to attach to hyphae of Drechslera sp. Candida sp. UICC Y-328 was potential in reducing the growth of Asp. ochraceus, and was investigated further for its potential as a biocontrol agent. Wounds on postharvest tomatoes were inoculated with 25 µl of yeast cellsuspension and 25 µl of mould spore suspension. The yeast cells wereinoculated 24 hours earlier before inoculation of mould spores on wounds of tomatoes. Biocontrol study showed that incidence of spoilage in postharvest tomatoes which were wounded and inoculated with Candida sp. UICC Y-328 and Asp. ochraceus, were reduced by 20% after 15-day incubation at room temperature. All postharvest tomatoes which were wounded and inoculated with Asp. ochraceus as control, were spoiled (100%). Synthetic fungicide Dithane M-45 at a concentration of 0.08% reduced spoilage incidence by 70%. Candida sp.UICC Y-328 was not effective as biofungicide in reducing spoilage incidence."

"Fusarium verticillioides is the causal agent of ear, stalk and root rot of maize that results in the severe reduction in yields and quality of infected products. Endophytic fungi have been purported as potential candidates in controlling pathogens since they are considered strong plant mutualists that confer disease resilience to their host. The present study was carried out to determine the in vitro antagonistic activity and biocontrol potential of endophytic Aspergillus spp. associated with P. amboinicus leaves against F. verticillioides. Three fungal endophytes from the genus Aspergillus were isolated and identified from the leaves of P. amboinicus, namely A. flavus, A. terreus and A. niger. The fungal isolates were tested for antagonism against F. verticillioides in dual culture plates. Results indicate that the Aspergillus endophytes can restrict growth of F. verticillioides and employ varying mechanisms of antagonism. A. niger inhibited F. verticillioides by 47.37%, followed by A. flavus (41.02%) and A. terreus (27.91%) respectively. Observations of dual culture plates revealed that A. flavus and A. niger antagonized the pathogen via overgrowth mechanism while A. terreus employed antibiosis to restrict the growth of F. verticillioides. The varying degrees of antagonism exhibited by the Aspergillus endophytes show their potential as biocontrol agents and source of bioactive compounds"

"Vachellia nilotica diintroduksi ke Taman Nasional Baluran (TNB) sejak tahun 1969 sebagai sekat bakar antara savana dan hutan tropis. Namun, tanaman tersebut tumbuh secara tidak terkendali dan menjadi tumbuhan invasif. Pengendalian secara mekanik dan kimia telah digunakan tapi belum berhasil menyelesaikan masalah tersebut. Solusi alternatif seperti penggunaan serangga sebagai agen pengendali hayati perlu diterapkan. Nilai Potensial serangga (NP) ditentukan oleh Indeks Nilai Penting (INP), dan hubungan filogeni serangga Indonesia dan Afrika. Penelitian dilakukan pada bulan Maret 2014 dengan 150 sampel V. nilotica menggunakan purposive sampling method dan line transect, sedangkan serangga dikumpulkan menggunakan metode beating tray. Terdapat 50 jenis serangga ditemukan pada V. nilotica. Lima jenis serangga dengan nilai NP yang tinggi dipilih. Jenis tersebut dikelompokan kedalam suku Geometridae (NP = 2.594 dan 2.004), Pyralididae (NP = 2.391), Aphididae (NP = 2.042), dan Membracidae (NP = 2.004). Geometridae dan Pyralididae adalah serangga yang paling direkomendasikan karena spesifisitas dan dominansinya. Penelitian lebih lanjut dianjurkan untuk melihat aktivitas serangga potensi sebagai pengendali hayati.

---

Vachellia nilotica was introduced to Baluran National Park (BNP) since 1969 as firebreaks between savana and tropical forest . However, this plant grows out of control and becomes invasive. Mechanical and chemical control have been used but have not managed to resolve the problem. Alternative solution such as using insect as biocontrol agent should be applied. Potential Value of insects (PV) is determined by the importance value index (IVI), and insect phylogeny relations between Indonesia and Africa insects. The study was conducted in March 2014, with 150 V. nilotica using purposive sampling method and line transects, while insects collected using beating tray method. There are 50 species of insects found on V. nilotica. Five species whose NP is high are choosen. These species grouped into Family Geometridae (PV= 2.594 and 2.004), Pyralididae (PV = 2.391), Aphididae (PV = 2.042), and Membracidae (PV = 2.004). Geometridae and Pyralididae are the most recommended insect because of their specificity and dominance. Further research need to be conducted to see the activity of insect as biocontrol."

"Bawang merah (Allium ascalonicum L.) adalah komoditas sayuran dengan ancaman penyakit hawar daun bakteri yang disebabkan oleh Pantoea sp. dalam produksinya. Pemanfaatan agen biokontrol dari bakteri yang berasosiasi dengan akar tanaman berpotensi tinggi menghasilkan mekanisme penghambatan patogen pada tanaman. Penelitian ini bertujuan untuk memperoleh isolat bakteri agen biokontrol yang mampu menghambat pertumbuhan patogen Pantoea sp., mempelajari karakterisasi dan mekanisme aktivitas agen biokontrol dalam penghambatan patogen Pantoea sp., serta mengidentifikasi isolat bakteri agen biokontrol. Kultur bakteri kandidat agen biokontrol diisolasi dari tanah perakaran tanaman bawang merah di lahan pertanian bawang merah di Cirebon dan Majalengka, Jawa Barat, serta Brebes, Jawa Tengah. Pengujian aktivitas meliputi uji antagonisme dan karakterisasi aktivitas biokontrol (produksi enzim protease, kitinase, selulase, siderofor, hidrogen sianida, ammonia, peroksidase dan aktivitas katalase) secara in vitro. Identifikasi isolat bakteri agen biokontrol dengan dilakukan gen 16S rRNA dan dilanjutkan dengan pembuatan rekonstruksi pohon filogenetik. Berdasarkan hasil penelitian, diperoleh 5 isolat rizobakteri (I-8, L1-9, L1-12, BM-L3(2), dan BM-L3(3)) yang memiliki kemampuan antagonis terhadap patogen Pantoea sp. penyebab penyakit hawar daun bakteri pada bawang merah. Kelima isolat tersebut menunjukkan hasil positif pada uji aktivitas enzim protease, kitinase, selulase, siderofor, hidrogen sianida, ammonia, peroksidase dan aktivitas katalase. Hanya isolat BM-L3(2) yang tidak memiliki kemampuan dalam produksi enzim kitinase. Isolat BM-L3(2) dan BM-L3(3) teridentifikasi sebagai Brevibacillus schisleri dan Bacillus sp., sedangkan isolat I-8, L1-9, dan L1-12 teridentifikasi sebagai Streptomyces rochei berdasarkan sifat morfologi, analisis sekuens 16S rRNA, dan kekerabatan pada hasil rekonstruksi pohon filogeni.

---

Shallot (Allium ascalonicum L.) is vegetable commodity that has the threat of bacterial leaf blight caused by Pantoea sp. in its production. Utilization of biocontrol agents from bacteria associated with plant roots has high potential to produce pathogen inhibition mechanisms in plants. This research aims to obtain bacterial isolates of biocontrol agents that are able to inhibit the growth of Pantoea sp., study the characterization and mechanism activity of biocontrol agents, and identify bacterial of biocontrol agents. Bacterial of biocontrol agent candidates were isolated from root soil of shallot plants in Cirebon, Majalengka, and Brebes. The activity of the antagonism and biocontrol charaterization (enzyme production of protease, chitinase, cellulase, siderophore, HCN, ammonia, peroxidase and catalase) was tested by in vitro. Identification of biocontrol agent bacterial with the 16S rRNA gene was carried out and continued with phylogenetic tree reconstruction. Based on the results of the study, 5 rhizobacterial isolates (I-8, L1-9, L1-12, BM-L3(2), and BM-L3(3)) were obtained that have antagonism activity as biocontrol agent bacteria against the pathogen Pantoea sp. causing bacterial leaf blight in shallots. The five isolates showed positive results in the enzyme activity tests of protease, chitinase, cellulase, siderophore, hydrogen cyanide, ammonia, peroxidase, and catalase. Only isolate BM-L3 (2) does not have the ability to produce chitinase enzyme. Isolates BM-L3(2) and BM-L3(3) were identified as Brevibacillus schisleri and Bacillus sp., while isolates I-8, L1-9, and L1-12 were identified as Streptomyces rochei based on morphological characters, 16S rRNA sequence analysis, and kinship on phylogeny tree reconstruction results."