Search

Actinobacteria are Gram-positive bacteria that can produce various secondary metabolites, including pigments that have potential as antioxidants. This study assessed the characteristics of yellowish-orange pigmented actinobacteria. The antioxidant activity of their extract pigment was tested by DPPH and analyzed by LC-MS. The identification results based on the 16S rRNA gene showed that the HRA isolate had 99.91% similarity value to Streptomyces gramineus JR-43, the HVA isolate had 99.22% similarities value to S. tendae ATCC 19812 and the HVB isolate had 81.18% similarities value to Rhodococcus ruber DSM 43338. Meanwhile, AGM 2.2 and 2.3 isolates had similarities to S. xanthophaeus NRRL B-5414 with similarity values of 98.95% and 99.82%, respectively. The Inhibitory Concentration (IC50) of actinobacterial crude extract pigments ranges from 53.38 µg/ml to 184.38 µg/ml. The HVB isolates with the major compound luteolin, have the highest antioxidant activity. The crude extract pigment of H [ABSTRACT FROM AUTHOR]

Ficus deltoidea is a medicinal plant that has high endophytic actinobacteria diversity. Endophytic actinobacteria play an important role in producing various types of bioactive compounds including α-glucosidase inhibitor. Screening of 40 endophytic actinobacteria isolates from F. deltoidea showed that 77% of them had inhibitory activity against rat α-glucosidase. The 64% of isolates that have rat α-glucosidase inhibitor activity were derived from leaves. TBL 7, TBL 24, TBS 3, TBS 17 and TBR 20 have high activity. Based on the molecular identification of the 16S rRNA gene, five selected isolates have similarity with Streptomyces spp. The aqueous and n-hexane extracts of TBL 7 isolates had the lowest IC50 values of 159.25 µg/ml and 118.52 µg/ml, respectively. Qualitative phytochemical analysis showed that aqueous and n-hexane extracts of TBL 7 contained flavonoids, phenols, alkaloids, triterpenoids, tannins, and saponins. These results showed that endophytic actinobacteria from F. detoidea have the potential to be developed as α-glucosidase inhibitor. [ABSTRACT FROM AUTHOR]

One source of bacteria that has not been widely explored is lactic acid bacteria originating from honeycomb (hive). Timor Island has a wealth of giant honey bees (Apis dorsata). Lactic acid bacteria from the Apis dorsata hive in Timor Island need to be investigated to obtain probiotic candidates with specific functional properties. Lactic acid bacteria were isolated from honeycomb by using de Mann, Rogosa, and Sharpe agar supplemented with 1% of CaCO3. Bacterial isolates that formed clear zones and were Gram-positive and catalase-negative were determined as lactic acid bacteria. The probiotic candidates are isolates that are resistant to bile salts and low pH; susceptible to antibiotics; are able to aggregate, autoaggregate, and coaggregate; and have antibacterial activities. Isolate MC7 was selected as a probiotic candidate and had inhibitory activity against angiotensin-converting enzyme (ACE) with IC50 263,098 ppm. Isolate MC7 showed weak inhibition against α-glucosidase activity. Molecular identification based on 16S rRNA gene showed that MC7 isolate was closely related to Lactobacillus rhamnosus with 100% similarity. Therefore, isolate MC7 was recommended as a probiotic candidate with a functional property as an inhibitor of ACE. [ABSTRACT FROM AUTHOR]

Sponge-associated actinobacteria are known as bioactive compounds producers with various biological functions, but their potency as plant growth promoters is rarely reported. This research aimed to investigate the potency of sponge-associated actinobacteria as plant growth promoters. Sponges used in these study were Callyspongia sp., Callyspongia aerizusa, Carteriospongia contorta, Chelanoplysilla sp., and Diacarnus bismarckensis. A total of 53 isolates have been isolated from that sponges by serial dilution method. All isolates classified into two groups, including non-Streptomyces and Streptomyces based on their morphological characters. Screening of sponge-associated actinobacteria isolates showed from 53 isolates there are 47 isolates produced indole acetic acid (IAA), 33 isolates inhibited the growth of Xanthomonas oryzae, 29 isolates grew on free N medium, 22 isolates produced HCN, eleven isolates inhibited the growth of Pyricularia oryzae, and five isolates had the capacity to solubilize phosphate. The results suggested that sponge-associated actinobacteria have the potency as plant growth promoter candidates and might be as biofertilizer on tidal lands. [ABSTRACT FROM AUTHOR]

The research was conducted to study the metagenomic of actinomycetes based on 16S ribosomal RNA (rRNA) and bacterial nifH genes in soil and roots of four rice cultivars. The denaturing gradient gel electrophoresis profile based on 16S rRNA gene showed that the diversity of actinomycetes in roots was higher than soil samples. The profile also showed that the diversity of actinomycetes was similar in four varieties of rice plant and three types of agroecosystem. The profile was partially sequenced and compared to GenBank database indicating their identity with closely related microbes. The blast results showed that 17 bands were closely related ranging from 93% to 100% of maximum identity with five genera of actinomycetes, which is Geodermatophilus, Actinokineospora, Actinoplanes, Streptomyces and Kocuria. Our study found that Streptomyces species in soil and roots of rice plants were more varied than other genera, with a dominance of Streptomyces alboniger and Streptomyces acidiscabies in almost all the samples. Bacterial community analyses based on nifH gene denaturing gradient gel electrophoresis showed that diversity of bacteria in soils which have nifH gene was higher than that in rice plant roots. The profile also showed that the diversity of those bacteria was similar in four varieties of rice plant and three types of agroecosystem. Five bands were closely related with nifH gene from uncultured bacterium clone J50, uncultured bacterium clone clod-38, and uncultured bacterium clone BG2.37 with maximum identity 99%, 98%, and 92%, respectively. The diversity analysis based on 16S rRNA gene differed from nifH gene and may not correlate with each other. The findings indicated the diversity of actinomycetes and several bacterial genomes analyzed here have an ability to fix nitrogen in soil and roots of rice plant. [ABSTRACT FROM AUTHOR]

This study aimed to isolate and screening the biological activity of paddy rhizosphere actinobacteria as indicated by their ability to produce extracellular enzymes, to function as antimicrobials agent, and as plant growth-promoting bioactive compounds producer. A total of 12 actinobacteria isolates was morphologically characterized based on their macroscopic and microscopic character of the colony. The Ts-23 isolate had the ability to inhibit the growth of Escherichia coli, while Ts-17 inhibited the growth of Staphylococcus aureus with 14.7 and 13.1 mm respectively. Four isolates are known to have the ability to inhibit the growth of Sclerotium rolfsii, i.e Ts-8, Ts-13, Ts-23, and Ts-24 isolates. All isolates have different abilities to produce extracellular enzymes. For amylase enzyme activity, Ts-16 yield 8.3 mm diameter of clear zone, while for protease activity Ts-8 produced 18.8 mm. The Ts-24 produced 30 mm clear zone cellulase activity. The Ts-24 was also capable to produce 7.5 mg.L-1 IAA. Based on 16S rRNA gene sequence analysis, the selected Ts-24 was closely related with Streptomyces sp. [ABSTRACT FROM AUTHOR]

The taxonomic positions of actinomycete strains ID03-0915T and ID03-0825, isolated from soil on the Indonesian island of Bali, were examined using a polyphasic taxonomic approach. The morphological and chemotaxonomic characteristics of these organisms are typical of the genus Streptomyces. Phylogenetic analyses performed using almost-complete 16S rRNA gene sequences demonstrated that the strains were closely related to Streptomyces glauciniger and Streptomyces lilacinus. However, DNA-DNA hybridization and phenotypic characteristics revealed that the strains differed from known Streptomyces species. Therefore, we conclude that strains ID03-0915T and ID03-0825 (=BTCC B-563) represent a novel species of the genus Streptomyces, for which we propose the name Streptomyces baliensis sp. nov. The type strain is strain ID03-0915T (=BTCC B-608T=NBRC 104276T).