Isolation Of Actinobacteria Research Articles

Sustainable bioconversion of rice straw into indole-3-acetic acid by Streptomyces coelicoflavus using response surface methodology

AbstractRice straw is an abundant agricultural waste that poses environmental disposal challenges and can be utilized for biotechnological applications. This study investigates the potential of actinobacteria to enhance rice straw biodegradation and sustainable indole-3-acetic acid (IAA) production, addressing the need for sustainable agricultural practices. Certain actinobacteria strains can effectively degrade rice straw while optimizing IAA production under controlled fermentation conditions. Twenty actinobacteria isolates were screened for lignocellulolytic enzyme activity, and ten were selected for rice straw biodegradation. IAA production was further optimized using response surface methodology based on temperature, pH, and agitation speed (RPM). Isolate S16 achieved a degradation rate of 68.75%, while S18 produced the highest IAA concentration (1040.625 μg/mL) under optimized conditions (25 °C, pH 9, 160 RPM). The purified IAA significantly improved Medicago sativa L. growth. Furthermore, the 16S rRNA gene sequence of isolate S18 was identified it as Streptomyces coelicoflavus strain NSH24 with accession number PP 320383.1. These findings underscore the potential of actinobacteria to efficiently convert agricultural waste into valuable bioproducts and promote sustainable farming practices. By transforming rice straw into high-value products like IAA, this approach contributes to a circular economy, offering an environmentally friendly solution for biomass utilization and agricultural sustainability.

Biosynthesis and Characterization of Zinc Nanoparticles Using Strains of Pseudomonas and Actinobacteria

Research was carried out at the Green Nanotechnology Laboratory, University of Agricultural Sciences, Dharwad, Karnataka, with a specific emphasis on the biosynthesis of zinc nanoparticles using Pseudomonas and Actinobacteria. Collection and screening of Pseudomonas and Actinobacterial isolates were done at Microbial Genetics Laboratory, Department of Agricultural Microbiology, UAS, Dharwad. The ZnNPswere biosynthesized and characterized through UV-Visible spectroscopy, Particle Size Analyzer (PSA), Scanning Electron Microscope (SEM), Energy-dispersive X-ray spectroscopy (EDS), X-Ray Diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR). The ZnNPs synthesized through Pseudomonas(AUDP209) and Actinobacteria(AUDT636)isolates exhibited peak values at 365 and 374 nm, with average sizes of 48.7 nm and 54.9 nm, respectively.SEM images revealed the spherical shape of the biosynthesized ZnNPs, while EDX confirmed the zinc ions presence in the biosynthesized samples and the crystalline structure of the ZnNPswas confirmed by XRD.FTIR spectroscopy confirmed the organic compounds present in the microbial extracts responsible for the capping and stabilizing agents for biosynthesis of ZnNPs.

Isolation, selection, and characterisation of sponge-associated actinobacteria against Staphylococcus aureus in the Kien Giang sea area

Isolation, selection, and characterisation of sponge-associated actinobacteria against Staphylococcus aureus in the Kien Giang sea area

Secondary metabolite profile of Streptomyces spp. changes when grown with the sub-lethal concentration of silver nanoparticles: possible implication in novel compound discovery.

The decline of new antibiotics and the emergence of multidrug resistance in pathogens necessitates a revisit of strategies used for lead compound discovery. This study proposes to induce the production of bioactive compounds with sub-lethal concentrations of silver nanoparticles (Ag-NPs). A total of Forty-two Actinobacteria isolates from four Saudi soil samples were grown with and without sub-lethal concentration of Ag-NPs (50µgml-1). The spent broth grown with Ag-NPs, or without Ag-NPs were screened for antimicrobial activity against four bacteria. Interestingly, out of 42 strains, broths of three strains grown with sub-lethal concentration of Ag-NPs exhibit antimicrobial activity against Staphylococcus aureus and Micrococcus luteus. Among these, two strains S4-4 and S4-21 identified as Streptomyces labedae and Streptomyces tirandamycinicus based on 16S rRNA gene sequence were selected for detailed study. The change in the secondary metabolites profile in the presence of Ag-NPs was evaluated using GC-MS and LC-MS analyses. Butanol extracts of spent broth grown with Ag-NPs exhibit strong antimicrobial activity against M. luteus and S. aureus. While the extracts of the controls with the same concentration of Ag-NPs do not show any activity. GC-analysis revealed a clear change in the secondary metabolite profile when grown with Ag-NPs. Similarly, the LC-MS patterns also differ significantly. Results of this study, strongly suggest that sub-lethal concentrations of Ag-NPs influence the production of secondary metabolites by Streptomyces. Besides, LC-MS results identified possible secondary metabolites, associated with oxidative stress and antimicrobial activities. This strategy can be used to possibly induce cryptic biosynthetic gene clusters for the discovery of new lead compounds.

Rhizosphere actinobacteria isolated from Pometia pinnata and its antimicrobial activity

Abstract. Janatiningrum I, Zahra A, Fitriyanti, Anggia V. 2024. Rhizosphere actinobacteria isolated from Pometia pinnata and its antimicrobial activity. Biodiversitas 25: 1007-1014. Actinobacteria are currently the largest antibiotic-producing bacteria due to their extreme environments such as soil, roots and rhizosphere. The diversity of rhizosphere actinobacteria is affected by plant exudates. Pometia pinnata is a plant that has long been used for traditional medicine in Indonesia. This study was aimed at isolating and evaluating isolate and evaluate the actinobacteria rhizosphere of P. pinnata, to screen their antibacterial and antifungal properties. Isolation of actinobacteria was done by using serial dilution method and grown on media. About 34 actinobacteria were successfully isolated from the rhizosphere of P. pinnata and 50% of them showed index antimicrobial activity for Staphylococcus aureus ATCC 6538 (0.52), Streptococcus pneumoniae ATCC 1705 (2.87), and Escherichia coli ATCC 25922 (1.28). Several microbial isolated microbes (20.8%) were found capable in inhibiting fungal growth. The highest antibacterial activity against all bacteria was shown by RM12 isolate. The aqueous fraction of RM12 isolate demonstrated a significant inhibitory activity against S. aureus ATCC 6538 and E. coli ATCC 25922 at concentrations of 250 ppm, 500 ppm and 1000 ppm. TLC bioautography showed that aqueous fraction RM 12 do not belong to the polyphenol or phenol compound group. The RM12 was characterized by using 16S ribosomal RNA sequence found to belong to actinobacteria genera to Streptomyces bungoensis.

Exploring actinobacteria isolated from coral originated from Tulamben Bali in inhibiting multidrug resistance bacteria

Increasing bacterial resistance has reduced the effectiveness of most clinical antibiotics. The limited option of antibiotics to treat Multi-Drug Resistance pathogen infections indicates that there is an urgency to explore new antibiotic candidates. Coral is recognized to produce bioactive compounds that have the potential to develop new medicinal materials with antibacterial properties. The use of marine invertebrates for compound production will reduce populations in nature, therefore associated microbes are preferred due to their environmental friendliness. Actinobacteria is one of the coral-associated microbes capable of producing active compounds of secondary metabolites as antibacterials. This study aimed to identify coral and obtain isolates of Actinobacteria associated with coral potential as an antibacterial against MDR bacteria. This research uses an explorative method. The method used is coral identification based on the morphology and shape of the sclerite. Screening of antibacterial activity was carried out using the agar plug method, microscopic observation using Gram staining and molecular identification of potential isolates by PCR. The results showed that the coral genera obtained were Siphonogorgia sp., Menella sp., Echinomuricea sp., Dendronephthya sp., and Epizoanthus sp. The results of antibacterial activity indicated that 19 isolates inhibited the growth of MDR pathogen bacteria. However, only the potential isolates were identified. The microscopic observations showed isolate III.ISP2.10-2.3 and III.ISP2.10-2.6 have Gram-positive coccus and bacillus-shaped, respectively. Potential isolates III.ISP2.10-2.3 (Micrococcus yunnanensis) were found to have antibacterial activity against Acinetobacter baumanii, Pseudomonas aeruginosa, and Bacillus subtilis, while isolate III.ISP2.10-2.6 (Brevibacterium pigmentatum) had the greatest activity against B. subtilis.

Characterization of Actinobacteria strains in Lebanese soil with an emphasis on investigating their antibacterial activity.

With the alarming rise of drug resistant pathogens, the quest for new bioactive compounds from natural habitats has increased. Actinobacteria are Gram-positive bacteria, considered prominent natural antibiotic synthesizers. This study aimed at isolating Actinobacteria from agricultural soil samples of Tamnine El Tahta and Haddatha, with an emphasis on the physicochemical soil characteristics. It also aimed at screening and identifying the antibacterial-producing Actinobacteria, with a determination of the chemical composition of the extract. Forty-six Actinobacteria were isolated from six soil samples. Actinobacteria load exhibited a positive correlation with moisture content, and a negative correlation with pH, salinity, and organic matter content. Primary screening for antibacterial activity was performed against various Gram-positive and Gram-negative bacteria by cross-streak method. Fourteen Actinobacteria isolates were potent against the test microorganisms, and the most effective isolate (T25) was selected for identification, and extract preparation. The antibacterial activity of the extract was tested using secondary screening, in addition to minimal inhibitory concentration (MIC), and minimal bactericidal concentration (MBC) determination. T25 isolate exhibited a 92% similarity with Micrococcus luteus/lylae. MIC recorded was 12.5mg/ml and the MBC was higher than 100mg/ml against all test microorganisms. Total phenol content was estimated to be 18.5 ± 0.0015mg GAE/g dry weight using Folin-Ciocalteu method, and total flavonoid content recorded 2.3 ± 0.02mg RE/g dry weight using aluminum nitrate colorimetric method. This study revealed that the physicochemical parameters in soils impact the distribution of Actinobacteria. Moreover, it focuses on Micrococcus luteus/lylae strain, considered a promising antibacterial resource for further potential clinical investigations.

Control of pathogenic bacteria using marine actinobacterial extract with antiquorum sensing and antibiofilm activity

ObjectiveThe objectives of this research were to screen the anti-quorum sensing and antibiofilm activity of marine actinobacteria, isolated from several aquatic environments in Indonesia against several pathogenic bacteria, such as Staphylococcus aureus, Bacillus cereus, Enterococcus faecalis, Vibrio cholerae, Salmonella Typhimurium, and Pseudomonas aeruginosa.ResultsTen out of 40 actinobacteria were found to have anti-quorum sensing activity against wild-type Chromobacterium violaceum (ATCC 12472); however, the validation assay showed that only eight of 10 significantly inhibited the quorum sensing system of Chromobacterium violaceum CV026. The crude actinobacteria extracts inhibited and disrupted biofilm formation produced by pathogens. The highest antibiofilm inhibition was discovered in isolates 11AC (90%), 1AC (90%), CW17 (84%), TB12 (94%), 20PM (85%), CW01 (93%) against Staphylococcus aureus, Bacillus cereus, Enterococcus faecalis, Vibrio cholerae, Salmonella Typhimurium, and Pseudomonas aeruginosa, respectively. The highest biofilm destruction activity was observed for isolate 1AC (77%), 20PM (85%), 16PM (72%), CW01 (73%), 18PM (82%), 16PM (63%) against Staphylococcus aureus, Bacillus cereus, Enterococcus faecalis, Vibrio cholerae, Salmonella Typhimurium, and Pseudomonas aeruginosa, respectively. Actinobacteria isolates demonstrated promising anti-quorum and/or antibiofilm activity, interfering with the biofilm formation of tested pathogens. Appropriate formulations of these extracts could be developed as effective disinfectants, eradicating biofilms in many industries.

Detection of actinobacteria from sediment soil: Exploration of metabolites as fungal plant pathogen inhibitors and plant growth promoters

The rhizosphere is an area with dense microbial activity. Actinobacteria are one among the rhizomicroflora inhabiting in the plant rhizosphere by protecting plants from pathogens by producing secondary metabolites, as plant growth promoters and by producing hydrolytic enzymes. But in the modern era of agriculture, the outrageous use of chemical fertilizers in the agriculture fields is causing major environmental pollution and the agricultural soil is losing its texture and fertility. So, in the present study, we aimed to isolate and screen indigenous actinobacterial strains which are capable of producing antifungal metabolites, plant growth promoting ability and hydrolytic enzymes. A total of 23 isolates of actinobacteria have been isolated. Among all the other actinobacterial isolates, Streptomyces sp. DRPG-15, which was isolated from the sediment soil of the Tamankal River, revealed a noticeable antagonistic activity against Macrophomina phaseolina for Sorghum and Sclerotium rolfsii for Chickpeas respectively. 16S rRNA sequence analysis showed that the Streptomyces sp. DRPG-15 exhibited 100% homology with Streptomyces enissocaesilis DRPG-15 OP985046. All 23 isolates were screened for the production of indole acetic acid, hydrogen cyanide, ammonia production and nitrate reduction and were also screened for various hydrolytic enzymes like Caseinase, Protease, Cellulase, Amylase, Chitinase, Pectinase, Gelatinase, L-asparaginase and Streptomyces sp. DRPG-15 was the only isolate that showed positive results for antagonistic activity, plant growth-promoting ability and enzymatic activity. The entire study indicates that the selected strain of Streptomyces sp. DRPG-15 is implying its possible utilization as a natural bioinoculant for sustainable agriculture.

Genetic diversity, plant growth promotion potential, and antimicrobial activity of culturable endophytic actinobacteria isolated from Aconitum carmichaelii Debeaux.

This study evaluated the phylogenetic diversity, plant growth promotion capacity, antifungal activity, and biocontrol potential of culturable actinobacterial endophytes isolated from the medicinal plant Aconitum carmichaelii Debeaux. Isolation of actinobacteria from healthy A. carmichaelii plants was carried out on six different media. Full-length 16S rRNA gene was amplified by PCR from the genomic DNA of each strain. Indole-3-acetic acid and siderophore production were quantitatively assessed by the Salkowski and Chrome Azurol S methods, respectively. Rice seeds germination and seedling growth were employed to evaluate plant growth promotion capacities of candidate strains. Dual-culture assay and pot experiments were performed to investigate the antifungal and biocontrol potential of isolates. We obtained 129 actinobacterial isolates from A. carmichaelii, and they belonged to 49 species in 7 genera. These strains exhibited diverse plant growth promotion ability, among which one strain significantly enhanced rice seeds germination, while 31 strains significantly facilitated rice seedling growth. SWUST-123 showed strong antifungal activity against four pathogens in vitro and was most compatible with Qingchuan cultivar. SWUST-123 reduced around 40% of southern blight disease occurrence compared to blank control treatment. . Aconitum carmichaelii harbored genetically diverse actinobacterial endophytes exhibiting diverse plant growth promotion and antifungal potential, some of which can be served as good candidates for biofertilizers and biocontrol agents.

Taxonomic and ecophysiological characteristics of actinobacteria in soils of the dry steppe zone of the Selenga Highlands (Western Transbaikalia).

Arid habitats have recently attracted increasing attention in terms of biodiversity research and the discovery of new bacterial species. These habitats are among the target ecosystems suitable for isolating new strains of actinobacteria that are likely to produce new metabolites. This paper presents the results on the isolation of actinobacteria from soils of the dry steppe zone of the Selenga Highlands, the characterization of their taxonomic diversity, as well as ecological and trophic properties. The bacterial counts on ISP 4 medium ranged from 6.6 × 105 to 7.1 × 106 CFU/g. The highest bacterial counts were observed in the subsurface and middle horizons of the studied soils. 28 strains of Gram-positive bacteria represented by thin-branched mycelium, coccoid and bacilliform forms were isolated. According to the results of 16S rRNA gene analysis, the isolated strains were representatives of Streptomyces, Arthrobacter, Glycomyces, Kocuria, Microbacterium, Micromonospora, Nocardioides, Pseudarthrobacter, and Rhodococcus (Actinomycetota). One isolate that showed low 16S rRNA gene sequence similarity with previously isolated and validly described species was a new species of the genus Glycomyces. It was shown that all tested strains are mesophilic, prefer neutral or slightly alkaline conditions, have growth limits in the temperature range of 5-45 °C and pH 6-9. The optimal NaCl concentration for growth of most strains was 0-1 %. The strains under study were capable of utilizing a wide range of mono- and disaccharides and polyatomic alcohols as a carbon source. The isolated strains were capable of using both organic (proteins and amino acids) and inorganic (ammonium salts and nitrates) compounds as nitrogen sources. The examinations of extracellular enzymes showed that all isolates were capable of producing catalase and amylase; 78.6 % of the total number of isolates produced protease and lipase; 53.6 %, cellulase; and 28.6 %, urease. The data obtained expand current knowledge about the diversity of microbial communities in soils of the Selenga Highlands and also confirm the potential of searching for new actinobacteria species in these soils.

Isolation and Characterization of Actinobacteria from Algerian Saline Soil Samples with Antimicrobial Activities

SECOND RESEARCH PAPER: Isolation and Characterization of Actinobacteria from Algerian Saline Soil Samples with Antimicrobial Activities

IMPACT OF ACTINOBACTERIA ON THE GROWTH AND ACCLIMATIZATION OF MICROPROPAGATED RUBUS FRUTICOSUS L. PLANTS TO EX VITRO CONDITIONS

Microcloning is an effective method of plant reproduction that is actively developing in Ukraine for the mass propagation of valuable food crops such as blackberries. However, the problem of losing a large number of microclones often arises during the ex vitro acclimatization stage. Inoculation of the rhizosphere with potentially useful microorganisms could have a positive impact on the survival rate and biometric characteristics of acclimatized seedlings. The aim of this study was to establish the impact of 23 actinobacteria isolates on blackberry microclones (Rubus fruticosus L.) during acclimatization to ex vitro conditions, and to determine the protective potential and plant growth-promoting effects of these bacteria. Methods. The antagonistic properties of the experimental microorganisms were determined using the agar block method. Bacteria were inoculated into the rhizosphere of blackberry microclones before planting in the soil. Results. The antagonistic activity of actinobacteria against phytopathogenic fungi P. expansum, P. variotii, A. niger, C. cladosporioides, F. oxysporum, A. alternata, R. cerealis, and A. tenuissima was established. The positive effect of bacteria on micropropagated blackberry plants during acclimatization to ex vitro conditions resulted in an increase in the survival rate of microclones in the soil by 34.8%, average height of experimental plants by 2.0 cm, node number by 3.4 nodes, and leaf area by 0.4 cm2. Conclusion. It was established that isolates of mycelial actinobacteria Lim4, Myt7ch, Conc32, Conc4 were promising inoculants for ex vitro acclimatization of micropropagated plants and could be recommended for the subsequent research in order to establish the interaction mechanisms between these microorganisms and plants.

Potential of actinobacteria as biocontrol agents to Xanthomonas oryzae pv. oryzae in vitro

Xanthomans oryzae pv. oryzae (Xoo) is a pathogen that causes bacterial leaf blight in rice plants.Biological control using microorganisms, one of which incorporates actinobacteria, is one of the most extensively used control techniques. This work aimed to find actinobacteria isolates from rice that can inhibit Xoo growth in vitro. A Completely Randomized Design (CRD) was employed in this experiment, with 14 treatments and three replications. There are 13 isolates used: Act-Hr 49, Act-Hr 21, Act-Hr 24, Act-Pha 4, Act-Mn2, Act-LB3, Act Pha 2.3, Act Pha 3.4, Act-Pha 3.3, Act-Hr 47, Act Pha 3.5, Act-Krj 21, Act-SK2 and control (Xoo without Actinobacteria treatment). The ability of actinobacterial isolates to reduce Xoo growth in vitro and the enzyme activity of each isolate were measured. The study revealed that three Actinobacteria isolates, Act-LB3, Act-Mn2, and Act-Pha4, could potentially suppress Xoo bacteria’s growth with inhibition indices ranging from 12 mm to 15 mm Act-LB3 isolate produced catalase enzyme, while Act-Pha4 isolate produced both catalase and protease enzyme. The results indicate that actinobacteria from the rice rhizosphere could produce antibacterial metabolites and enzyme activity.

Actinobacteria from Arctic and Atlantic deep-sea sediments-Biodiversity and bioactive potential.

The deep-sea covers over 70% of the Earth's surface and harbors predominantly uncharacterized bacterial communities. Actinobacteria are the major prokaryotic source of bioactive natural products that find their way into drug discovery programs, and the deep-sea is a promising source of biotechnologically relevant actinobacteria. Previous studies on actinobacteria in deep-sea sediments were either regionally restricted or did not combine a community characterization with the analysis of their bioactive potential. Here we characterized the actinobacterial communities of upper layers of deep-sea sediments from the Arctic and the Atlantic (Azores and Madeira) ocean basins, employing 16S rRNA metabarcoding, and studied the biosynthetic potential of cultivable actinobacteria retrieved from those samples. Metabarcoding analysis showed that the actinobacterial composition varied between the sampled regions, with higher abundance in the Arctic samples but higher diversity in the Atlantic ones. Twenty actinobacterial genera were detected using metabarcoding, as a culture-independent method, while culture-dependent methods only allowed the identification of nine genera. Isolation of actinobacteria resulted on the retrieval of 44 isolates, mainly associated with Brachybacterium, Microbacterium, and Brevibacterium genera. Some of these isolates were only identified on a specific sampled region. Chemical extracts of the actinobacterial isolates were subsequently screened for their antimicrobial, anticancer and anti-inflammatory activities. Extracts from two Streptomyces strains demonstrated activity against Candida albicans. Additionally, eight extracts (obtained from Brachybacterium, Brevibacterium, Microbacterium, Rhodococcus, and Streptomyces isolates) showed significant activity against at least one of the tested cancer cell lines (HepG2 and T-47D). Furthermore, 15 actinobacterial extracts showed anti-inflammatory potential in the RAW 264.4 cell model assay, with no concomitant cytotoxic response. Dereplication and molecular networking analysis of the bioactive actinobacterial extracts showed the presence of some metabolites associated with known natural products, but one of the analyzed clusters did not show any match with the natural products described as responsible for these bioactivities. Overall, we were able to recover taxonomically diverse actinobacteria with different bioactivities from the studied deep-sea samples. The conjugation of culture-dependent and -independent methods allows a better understanding of the actinobacterial diversity of deep-sea environments, which is important for the optimization of approaches to obtain novel chemically-rich isolates.

Screening of indigenous actinobacteria as biological control agents of Colletotrichum capsici and increasing chili production

BackgroundAnthracnose disease caused by Colletotrichum capsici is a major disease in chili plants that is difficult to control. Actinobacteria have potential biological control agents for C. capsici because of their antifungal properties and dominant presence in soil. The study aimed to obtain actinobacteria isolates that have the potential to control anthracnose in planta and increase the growth and production of chili plants. The study consisted of three stages: isolation, selection, and characterization of the best actinobacteria isolates. A total of 20 isolates of indigenous actinobacteria were isolated, and 16 isolates were successfully selected based on the results of the biosafety test.ResultsThe in planta test showed that eight isolates could control anthracnose with 100% effectiveness. Of the eight isolates, as many as five players increased the production of chili plants by 169.51–218.53 g. Actinobacterial isolates that have the potential to control anthracnose disease in planta and increase the growth and production of chili plants are ARAI 3221, ARAC 3221, ARAC 2211, ARAC 3321, and ARTI 1312. These isolates produced indole acetic acid (IAA) with concentrations of 25.82–88.87 ppm, and four isolates were able to dissolve phosphate. Five isolates produced chitinase enzyme with the chitinolytic index of 0.32–1.78.ConclusionThe introduction of actinobacteria in chili plants was also proven to extend the incubation period, reduce the incidence of disease, and reduce the severity of anthracnose disease compared to negative controls and mancozeb. Actinobacteria can suppress pathogenic microorganisms that can inhibit plant growth. Actinobacteria have the potential to increase the growth and production of chili plants. The results of 16S rRNA sequences showed that the five potential isolates were identified as Streptomyces cellulose, S. fradiae, S. olivaceus, S. pseudogriseolus, and S. griseoflavus.

Multifeature analysis of age-related microbiome structures reveals defense mechanisms of Populus tomentosa trees.

Root microbiota composition shifts during the development of most annual plants. Although some perennial plants can live for centuries, the host-microbiome partnerships and interaction mechanisms underlying their longevity remain unclear. To address this gap, we investigated age-related changes in the root metabolites, transcriptomes, and microbiome compositions of 1- to 35-yr-old Populus tomentosa trees. Ten co-response clusters were obtained according to their accumulation patterns, and members of each cluster displayed a uniform and clear pattern of abundance. Multi-omics network analysis demonstrated that the increased abundance of Actinobacteria with tree age was strongly associated with the flavonoid biosynthesis. Using genetic approaches, we demonstrate that the flavonoid biosynthesis regulator gene Transparent Testa 8 is associated with the recruitment of flavonoid-associated Actinobacteria. Further inoculation experiments of Actinobacteria isolates indicated that their colonization could significantly improve the host's phenotype. Site-directed mutagenesis revealed that the hyBl gene cluster, involved in biosynthesis of an aminocyclitol hygromycin B analog in Streptomyces isolate bj1, is associated with disease suppression. We hypothesize that interactions between perennial plants and soil microorganisms lead to gradual enrichment of a subset of microorganisms that may harbor a wealth of currently unknown functional traits.

Isolation and Celulolytic Activity Assay of Actinobacteria Isolated from Palm Oil Wastewater

Cellulose plays an important role in the carbon cycle in nature and is the largest compound. This study aimed to isolate, to characterize and to determine actinobacteria that capable of producing cellulases. The sampling method in this study was carried out by purposive sampling at the outlet point of aeration pond of the wastewater treatment plant (IPAL) from palm oil waste station of PT. Teupin Lada. Isolation of actinobacteria was carried out on Humic Acid Vitamin b Agar (HVA), morphological characterization was carried out on Yeast Malt Agar (YMA), Yeast Starch Agar (YSA), Oatmeal Agar (OA), and microscopic characterization of actinobacteria and measuring the diameter of the clear zone formed on Carboxymethyl Cellulose (CMC) medium using the indicator Congo Red. Eight isolates were obtained from the isolation. Of the 8 isolates obtained, 7 of them were able to produce cellulase enzymes which were measured based on the clear zone formed in the test Congo Red on Carboxymethil Cellulose (CMC), and one isolate did not show any clear zones. The highest value of Cellulolytic Index (IS) was obtained from isolate ATLS-05, namely 8.38 mm. HIGHLIGHTS Cellulose plays an important role in the carbon cycle in nature and is the largest compound The high waste load especially palm oil mill effluent (Elaeis guineensis) or known as Palm Oil Mill Effluent(POME) could cause various problems for the environment and society. POME is wastewater from the palm oil industry, which is one of the most polluting agro-industrial wastes Actinobacteria are one of the soil microbes which have the greatest abundance and play an important role in the decomposition process. One of the roles of soil microbes is too degrading cellulose GRAPHICAL ABSTRACT

Exploring the Antimicrobials Production Potential of Actinobacteria Isolated from Caves at Bahadurkhel Karak, Pakistan

Cave actinobacteria are relatively less explored and are considered as the new targets for the discovery of novel antimicrobials, specifically against highly resistant pathogens such as extensively drug-resistant (XDR) Salmonella. In this study N=20 actinobacteria isolates were retrieved from the least disturbed caves situated at Bahadurkhel Karak, Pakistan (33° 16’ 52” North, 70° 79’ 07” East) and (33° 15’ 90” North, 70° 94’ 72” East). The isolates were identified using standard morphological and biochemical characterization procedures as well as by 16S rDNA sequencing. N= 16 isolates were targeted for further antimicrobial activity screening based on their preliminary morphological and biochemical identification. The methanolic extracts were prepared from the culture broth of the isolates by using Amberlite® XAD-16 resin to execute in situ solid phase extraction. The thin layer chromatography (TLC) showed the presence of a variety of different compounds in the crude extracts of the secondary metabolites. The extracts’ antimicrobial potential was analyzed against several test strains, including Salmonella enterica, Staphylococcus aureus, Bacillus subtilis, Klebsiella pneumoniae, and Escherichia coli. Among the isolated strains, the isolates SNK 93 and SNK47 were found to be the most active against the tested pathogenic bacteria, showing growth inhibition zones of 20 mm and 27 mm respectively against extensively drug-resistant (XDR) Salmonella. Based on these results it can be concluded that cave actinobacteria are a promising source of potentially novel antimicrobials against multidrug-resistant (MDR) and XDR pathogens.

Bacterial Community Composition and Isolation of Actinobacteria from the Soil of Flaming Mountain in Xinjiang, China

In this work, bacterial community composition and actinobacteria resources were explored in extremely hot and hyper-arid areas of Flaming Mountain. This was achieved through a combination of PCR amplicon sequencing of bacterial 16S rRNA gene and cultivation-dependent isolation and characterization efforts. According to the high-throughput sequencing results and soil characteristics, 11 kinds of media were firstly designed to isolate actinobacteria, following the screening and identification of related strains. The results showed that a total of 2994 operational taxonomic units (OTUs) were obtained, involving 22 phyla, 77 orders and 121 genera. Among them, actinobacteria with the relative abundance of 8% ranked third, accounting for 33 genera and 47 species. A total of 132 strains distributed by eight families and 11 genera of actinobacteria were isolated from 11 media, of which six strains were potential new species. Furthermore, the functional characteristics of isolated strains were preliminarily evaluated. The results showed that the obtained strains generally had tolerance against heat, salt and alkali. Fifty-two strains had antibacterial activity, 69 strains could produce hydrolases, and 12.4% of the strains had quorum sensing inhibitory activity. The present study has laid a solid foundation for further understanding the bacterial diversity and exploiting actinobacteria resources in the Flaming Mountain area.