A mesophilic, Gram-stain-positive, spore-forming bacterium that formed branched mycelia was isolated from paddy soil in Gunung Salak (Mount Salak), West Java, Indonesia. This strain, designated S-27T, grew at temperatures between 20 and 37 °C; the optimum growth temperature was 25 to 30 °C, and no growth was observed at 15 or 45 °C. The pH range for growth was pH 3.5 to 8.6; the optimum pH was 6.0, and no growth was observed at pH 3.0 or 9.2. Strain S-27T was able to hydrolyse polysaccharides such as starch, cellulose and xylan. The G+C content of the DNA of strain S-27T was 55.7 mol%. The major fatty acids were iso-C17 : 0 and C16 : 1 2-OH, and the major menaquinone was MK-9 (H2). The cell wall of strain S-27T contained d-glutamic acid, glycine, l-alanine, d-alanine, l-ornithine and β-alanine in a molar ratio of 1.0 : 1.6 : 1.4 : 0.6 : 0.9 : 1.1. The polar lipids consisted of phosphatidylglycerol, phosphatidylinositol and two glycolipids. The major cell-wall sugar was arabinose. Detailed phylogenetic analysis based on 16S rRNA gene sequences indicated that strain S-27T belongs to the order Ktedonobacterales and is most closely related to Ktedonobacter racemifer SOSP1-21T (89.6 % sequence identity). On the basis of its chemotaxonomic and phenotypic features and phylogenetic position, we concluded that strain S-27T represents a novel genus and species, for which we propose the name Dictyobacter aurantiacus gen. nov., sp. nov. The type strain of Dictyobacter aurantiacus is strain S-27T (=NBRC 109595T=InaCC B312T). Emendation of the description of the genus Thermosporothrix is also provided.
Irawati W, Ompusunggu NP, Susilowati DN, Yuwono T. 2019. Molecular and physiological characterization of indigenous copper-resistant bacteria from Cikapundung River, West Java, Indonesia. Biodiversitas 20: 344-349. The use of indigenous bacteria as bioremediation agents in wastewater treatments plant is a promising solution for tackling the environmental problem. The objectives of this research were to establish the phylogenetic tree and physiological characterization of copper-resistant bacteria isolated from Cikapundung River, West Java, Indonesia. A phylogenetic tree was constructed based on 16S rDNA sequences. Physiological characterization including growth and the potency of bacterial strain for copper accumulation and copper removal was also studied. Five highly copper-resistant bacteria designated as strains CN1, CN2, CN5, CN6, and CN8 have been isolated from Cikapundung river with the MICs (Minimum Inhibitory Concentration) of 5 mM-8mM. Sequence alignment and phylogenetic analysis showed that strains CN1 and CN6 belong to Klebsiella pneumoniae with the similarity of 99%. Meanwhile, strain CN2, CN5, and CN8 belong to Acinetobacter calcoaceticus, Acinetobacter sp. and Escherichia coli with the similarity of 99%, 96%, and 95%, respectively. The highest resistant bacterial isolates were strains CN6 and CN8 with the MICs of 8 mM. The highest accumulation capability was found in strain CN1 with a total of 4.62 mg/g dry weight of cells. Meanwhile, strain CN8 demonstrated the highest copper removal with the value of 48.15%.
Partial Purification and Characterization of Chitinase from Entomopathogenic Fungus Beauveria bassiana Isolate BB200109. Yadi Suryadi, Tri P. Priyatno, I Made Samudra, Dwi N. Susilowati, Nuni Lawati, and Eman Kustaman. Beauveria bassiana is one of the entomopathogenic fungus that produces chitinase when infecting its host. This study was aimed to purify, isolate and characterize chitinase of B. bassiana isolate BB200109. Pathogen identity was determined both morphologically and molecularly using ITS primer, whilst characterization was done at various conditions i.e. temperature, pH, metal ion and incubation time. Results showed that the BB200109 isolate belonged to B. bassiana. The isolate produced extracellular chitinase with chitinolytic index of 1.035. Partial purification of three saturated ammonium sulphate precipitation (10, 30, and 70%) showed maximum purity of 1.2 times, while dialysis could increase the purity of 1.9 times compared to that of crude enzyme extract. Characterization results showed that the chitinase isolated from B. bassiana isolate BB200109 had an optimum activity at pH 4, temperature 50 o C, and optimum incubation time of 90 minutes. , and Na + acted as inhibitors. The chitinase demonstrated lower affinity to chitin substrate as indicated by high K m value of 0.266 mg/l and a V max of 0.067 mg/l sec. Based on SDS-PAGE, chitinase from B. bassiana isolate BB200109 had molecular weight of 60.25 kDa. The study implied the potency of B. bassiana isolate BB200109 as extracellular chitinase producer with its enzyme charateristics seems to be developed as an insect biocontrol agent.
Rice blast caused by Pyricularia oryzae is a major disease affecting rice production grown in upland and wetland rice. Application of beneficial bacteria as seedling root dip and spraying method to protect against the disease may be an alternative strategy to chemical control. This research was aimed to explore the bacterial consortium that may control blast disease on rice plants. In this study, the following bacterial cultures and their consortiums were used: Bacillus firmus E65, Serratia marcescens E31, Pseudomonas aeruginosa C32b, Bacillus cereus II.14, and its combination for their suppression ability against P. oryzae under in-vitro conditions. The results showed that A2 (Bacillus firmus E65) and A6 consortium (Bacillus firmus E65, Bacillus cereus II.14, and Pseudomonas aeruginosa C32b) significantly reduced the mycelial growth of P. oryzae with the percentage inhibition of 73-85% and 66-83%, respectively. Further greenhouse testing conducted with use of formulative preparation of the two selected best treatments using talc, bentonite, palm oil, and suspensionbased carriers showed that spraying with suspension formulation had good effect in suppressing blast disease compared with that of other carriers evaluated.
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