Diversity Of Actinobacteria Research Articles

Discovery of two new actinobacteria, Micromonospora palythoicola sp. nov. and Streptomyces poriticola sp. nov., isolated from marine invertebrates

Marine invertebrates represent an underexplored reservoir for actinobacteria, which are known to synthesize novel bioactive compounds. This study isolated 37 actinobacterial strains from five distinct marine invertebrate hosts, namely Chondrilla australiensis, Palythoa sp., Favia sp., Porites lutea, and Acropora cervicornis, while no strains were obtained from Lissoclinum sp. and Lithophyllon sp. These isolates were taxonomically classified into six genera: Gordonia, Microbacterium, Micromonospora, Nocardia, Rhodococcus, and Streptomyces, with Streptomyces and Micromonospora being notably predominant. Comparative genomic analysis facilitated the identification of two novel species: Micromonospora palythoicola sp. nov. (strain S2-005T = TBRC 18343T and NBRC 116545T) and Streptomyces poriticola sp. nov. (strain C6-003T, =TBRC 17807T and NBRC 116425T). Both species exhibited substantial genetic differences from their nearest known species as demonstrated by digital DNA-DNA hybridization and average nucleotide identity scores, which fell below the thresholds of 70% and 95%, respectively. Streptomyces poriticola C6-003T displayed significant antimicrobial activity and selective cytotoxicity against human breast cancer MCF-7 cells, with reduced toxicity towards human dermal papilla cells. Micromonospora palythoicola S2-005T manifested antimicrobial properties against Streptococcus mutans and Kocuria rhizophila. These findings highlight the considerable diversity of actinobacteria within marine invertebrates and underscore their potential as a source of new species with promising biological properties for therapeutic applications.

Existence of rare actinobacterial forms in the Indian sector of Southern Ocean: 16S rRNA based metabarcoding study.

The significance of the Southern Ocean (SO) as a sink of atmospheric CO2 and other greenhouse gases is well established. Earlier studies have highlighted the role of microbes in various SO ecosystem processes. However, the diversity and role of actinobacteria in the Indian sector of SO (ISO) water and sediments are unknown. This study aimed to analyze the diversity of actinobacteria in water and sediment samples of SO based on amplicon microbiome analyses. The taxonomic analysis identified a total number of 27 phyla of which Proteobacteria (40.2%), Actinobacteria (13.6%), and Firmicutes (8.7%) were found to be dominant. The comparative study of water and sediment samples revealed the dominance of different actinobacteria in water and sediments. While the order Streptomycetales was dominant in the water samples, Micrococcales was found to be dominant in the sediment samples. The genus level analysis found the presence of eight and seventeen genera in the sediment and water samples, respectively. The genus Streptomyces, Saccharopolyspora, Nocardioides, Sva0996 marine group, and Mycobacterium were seen both in sediment and water samples. Marmoricola, Ilumatobacter, and Glaciihabitans were observed only in sediment samples whereas Rhodococcus, Corynebacterium, Micrococcus, Turicella, Pseudonocardia, Bifidobacterium, Nesterenkonia, Collinsella, Knoellia, Cadidatus, Actinomarina, Libanicoccus and Cutibacterium were noticed exclusively in water samples. Our study also emphasizes the need for further detailed study to understand the links between actinobacterial diversity and their ecological functions in the ISO. The available metabarcoding data paves the way for future research in cultivable forms of novel and rare Actinobacteria for their bioprospecting applications.

Actinobacteria diversity associated with sponge Amorphinopsis exacavans from Rancabuaya Beach, Garut, Indonesia

Abstract Sponges are complex marine organisms known for their symbiotic relationships with various bacterial communities, which play structural and functional roles within the sponge holobiont. Actinobacteria have received much attention because of their potential pharmaceutical applications. This study examines Amorphinopsis excavans profile, distinguishing between endosymbionts and ectosymbionts. The microbial grouping was characterized using Next Generation Sequencing (NGS) anchored to the 16S rRNA marker. The results showed that Proteobacteria and Firmicutes dominated both the endosymbiont and ectosymbiont communities at the phylum level. The actinobacterial diversity index at the genus level in both communities was 2.77 and 3.11, indicating moderate to high diversity without a dominant genus. For the genus level, the evenness scores of 0.81 and 0.89 indicated a high population type within the bacterial community. Relative abundance revealed the three most prevalent genera in the endosymbiont community were Rothia, Thermoplyspora, and Thermomonospora. In contrast, Kocuria, Mycobacterium, and Bifidobacterium were the three most common genera of ectosymbionts. Leuconostoc citreum was the first species known to be associated with a sponge. This study is a developing metagenomic assessment of actinobacterial diversity in A. excavans, providing novel insights into the sponge’s complex microbial ecosystem.

Actinobacteria diversity associated with marine sediments and a wetland system, Agulhas-South Africa

BackgroundSouth Africa is known for its great biodiversity. The Agulhas Plain represents one such unique environment where low-gradient topography has resulted in extensive wetland formation. It is fed by two major river systems, bringing in brackish, alkaline water. It has been exposed to major marine transgression and regression events, and harbours great Fynbos diversity as well as a Mediterranean-type climate, thereby creating unique ecosystems. It is therefore surprising that little is known about the bacterial diversity associated with the Agulhas Plain and associated marine ecosystems.MethodsIn this study, we focused on the actinobacterial diversity (Phylum Actinomycetota) associated with an emerging peatland on the Agulhas Plain (SF; Areas 1–3) and a marine site (ANP; Ocean, Rocky, Dry) located 10 km away from SF. A combined metataxanomics and isolation approach was taken to evaluate the actinobacterial diversity of the sampling sites and to determine the effect of environmental physicochemical parameters on these populations. Various genome analyses were performed on an Sva0096 marine bin to gain insight into its ecological role.ResultsMetataxanomics showed that the two sites shared defined major taxa, including Blastococcus, Geodermatophilus, Microbacterium, Mycobacterium, Nocardioides, Streptomyces, and the Sva0996 marine group. Analysis of the biosynthetic potential of an Sva0996 marine bin134 (obtained from GenBank) provided insights into the potential ecological role of this group of bacteria in both the marine and terrestrial environments. Higher actinobacterial diversity (Shannon index > 5) was observed for Areas 2 and 3 (SF), as well as the ANP Dry samples. The actinobacterial population composition was found to be driven by salinity, pH, Mn, and Ca, with certain areas of SF exhibiting similar (and even higher) salinity (SF: 70–100 Ω vs. ANP: 100–160 Ω) and lower pH levels (SF: 6.3-8.0 vs. ANP: 8.6–8.9) to that of the marine environment.ConclusionThis snapshot study has provided some insights into the actinobacterial diversity of the two sites studied. Analysis of an Sva0096 marine bin134 provided further insights into the potential ability of the Sva0096 marine group to survive in a unique terrestrial environment that is periodically exposed to environmental pressures that mimic the marine environment.

The Impacts of the Low-FODMAP Diet on the Management of Irritable Bowel Syndrome Symptoms: Possibilities, Feasibility, and Alternatives

Irritable bowel syndrome (IBS) is a common gastrointestinal (GI) condition characterized by a myriad of GI symptoms (e.g., diarrhea, nutrient malabsorption) that vary in severity. Due to its complex and individual nature, there is no known cure for IBS, but many diets have been assessed for their viability in managing symptoms. The low-FODMAP diet has recently been investigated for its potential benefits for IBS patients. FODMAPs, or Fermentable Oligosaccharides, Disaccharides, Monosaccharides, and Polyols are short- and medium-chain carbohydrates that are poorly absorbed in the small intestine and are prone to absorb water and ferment in the colon. Consumption of these FODMAPs correlates with increasing severity of IBS symptoms. The purpose of this randomized controlled trial systematic review was to compile various evidence-based dietary recommendations for the low-FODMAP diet for adult patients suffering from IBS from randomized controlled and clinical trials. The possibilities, feasibilities, and potential alternatives are proposed to determine if there is sufficient evidence to recommend the low-FODMAP diet for this patient population. Over 1,000 studies were screened and 6 were reviewed to determine the benefits of this diet. It was found that the low-FODMAP diet has demonstrated efficacy in delivering IBS symptom relief by changing patients’ metabolomes, microbiomes, and physiology. Specifically, this diet showed a greater overall decrease in abdominal pain, bloating, stool consistency, frequency, and urgency. Greater diversity of actinobacteria was found in the stool samples of these patients. Nociceptive neurons were also shown to be less sensitive and GI gas production was also markedly decreased. Despite these benefits, the low-FODMAP diet is more recommended for acute flare-ups due to its difficult adherence and attrition. Instead, we conclude that the balanced Mediterranean diet contains aspects of the traditional Mediterranean and low-FODMAP diet that can relieve IBS symptoms for daily life, while the low-FODMAP diet can be an effective treatment to ameliorate conditions when severe symptoms are experienced.

Разнообразие актинобактериальных сообществ в местах захоронения жидких отходов химического предприятия

The composition and taxonomic structure of the phylum Actinobacteria were studied on the example of technosols formed on the territory of the former tailings of liquid waste of a chemical enterprise in the floodplain of the Vyatka River. The diversity of actinobacteria in soil samples taken from three spatially remote monitoring sites (SG, SU1 and SU2), differing in the complex of physico-chemical properties and the nature of the vegetation cover, was studied. The results were compared with the background soil (BS) – alluvial soil selected on the territory of the Nurgush State Nature Reserve. The studies were carried out using high-performance sequencing using Illumina technology and the culture method (seeding). The culture method revealed representatives of the genera Streptomyces, Micromonospora, Streptosporangium and a number of oligospore forms in the actinobacterial complexes. The total number of actinomycetes in the samples of technosols varied from 2.4·104 to 1.8·105 CFU/g, and in the background soil was 8.5·103 CFU/g. Families of actinomycetes established by the seeding method were also detected using the amplicon sequencing of the V4 section of the 16S rRNA gene, but the molecular method made it possible to identify a number of other taxa in the studied samples, including those that do not have cultured representatives or are not yet classified. Using amplicon sequencing, it was found that representatives of the phylum Actinobacteria in samples of technogenically disturbed soils are absolute dominants in relative abundance in the total bacterial diversity. The proportion of actinobacteria in disturbed soils ranges from 33 to 41%, while in the background soil it is only 22%. Actinobacteria in the samples of technosols were represented by the families Micromonosporaceae, Micrococcaceae, Nocardioidaceae, Microbacteriaceae, Thermomonosporaceae, Pseudonocardiaceae, Actinosynnemataceae, and Intrasporangiaceae, etc. The taxonomic spectrum of actinobacteria in the BS sample was similar to technosols, but the proportion of taxa was different. The results obtained will be used in further studies of soil actinobiota in connection with changes in ecosystems disrupted by human economic activity, and are also of interest for the search and isolation of natural strains of actinobacteria for biotechnology purposes.

Morphological diversity of actinobacteria isolated from oil palm compost (Elaeis guineensis).

Composting is a natural process of decomposition of organic matter that occurs by the action of microorganisms such as fungi, bacteria, and actinobacteria. The actinobacteria are present throughout the process due to their resistance to different environmental conditions. They are Gram-positive, filamentous bacteria with a high capacity for producing secondary metabolites of biotechnological importance. Thus, the objective of this work was to isolate and characterize actinobacteria from industrial composting soil of oil palm (Elaeis guineensis) in the municipality of Igarapé-Açu, Pará. Ten samples of the material were collected and seeded on soy tryptone agar, Reasoner's 2A agar, and Columbia agar, using the serial dilution technique. For morphological characterization of the strains, Gram staining and microculture were performed, and for biochemical characterization, the motility, triple sugar iron, Simmons citrate, maltose, phenylalanine, catalase, and DNAse tests were performed. It was observed that compost actinobacteria have a great diversity in morphological and metabolic production, which may be associated with the substrate and cultivation conditions. Therefore, palm oil compost material represents a rich source of bacterial biodiversity, bringing new perspectives for the bioprospecting of actinobacteria of biotechnological importance in little explored environments.

Biodiversity of Actinobacteria Isolated from Marmara and Avşa Islands in Türkiye

The main purpose of this study is to investigate the microbial diversity of Actinobacteria, living in soils in the “Marmara” and “Avşa” Islands and to identify species at genus level based on 16S rRNA gene sequences. These islands are located in the southwest of the Sea of Marmara and in the literature review, no Actinobacteria biodiversity studies related to Marmara and Avşa Islands were found. Such unexplored ecological habitats are potentially rich source for discovery sources of novel species and bioactive molecule. Actinobacteria play an important role in many natural phenomena such as nitrogen fixation, roles of these prokaryotic microorganisms. In this article, we focused on the presence and the diversity of Actinobacteria on the Islands by examining multiple sampling sites and using different selective isolation media. A total of 400 culturable Actinobacteria were isolated using ten different isolation media by dilution-plating method. Among the 400 isolates, 112 isolates were selected according to their morphology in different culture media. The isolates were characterized on the basis of 16S ribosomal RNA gene sequencing and phylogenetic analysis. The results showed a high level of actinobacterial diversity with 16 different genera. These genera obtained as a result of phylogenetic analyzes are Streptomyces, Nonomuraea, Nocardia, Actinomadura, Micromonospora, Kribbella, Mycolicibacterium, Microbispora, Saccharopolyspora, Jiangella, Rhodococcus, Actinopolymorpha, Geodermatophilus, Dactylosporangium, Pseudonocardia and Nocardioides. Many isolates are identified as new species by our current research. Findings from this study showed that the soil of Marmara and Avşa Islands can be a good source of isolation for Actinobacteria.

Genetic and Physiological Diversity of Marine Actinobacteria from the Okha Coast, Gujarat, India

Saline and alkaline habitats of the Okha coastline, Gujarat, India, were explored for the diversity of actinobacteria. Based on the phenotypic and genotypic heterogeneity, nine haloalkaliphilic actinobacterial strains were characterized and identified. The PCR amplification of 16S rDNA using universal and genus-specific primers corroborated the trends that emerged through cultural and physiological characterization. Streptomyces was the most abundant genus amplified with the Streptomyces-specific primers (StreptB/E, StreptB/F), whereas other actinobacterial strains were amplified by the universal primers U1 and U2. Further molecular diversity was investigated by the gradient PCR-DGGE as a fingerprinting tool that generated group-specific DGGE patterns. Based on the nucleotide homology and phylogenetic analysis, strains OK-1 and OK-2 were identified as Streptomyces somaliensis. At the same time, OK-3 and OK-7 were detected as Streptomyces sp., while OK-5, OK-6, OK-8, OK-9, and OK-10 belonged to Nocardiopsis alba. Further, the cluster analysis using the UPGMA method generated 3 clusters based on biochemical characterization, sugar utilization, and enzyme production. The dendrogram based on the DGGE band pattern created with Jaccard-distance revealed two major clades with 33.33% similarity. Further, the study of alpha diversity calculation using phenotypic characteristics discloses highly diverse sugar utilization abilities. Moreover, a stress value of 0.1236 was obtained based on the NMDS analysis of the plots using Bary-Curties dissimilarity. Overall, the distinct phenotypic, metabolic, and molecular profiling illustrated the diversity among marine actinobacteria.

Bioprospecting of desert actinobacteria with special emphases on griseoviridin, mitomycin C and a new bacterial metabolite producing Streptomyces sp. PU-KB10–4

BackgroundBioprospecting of actinobacteria isolated from Kubuqi desert, China for antibacterial, antifungal and cytotoxic metabolites production and their structure elucidation.ResultsA total of 100 actinobacteria strains were selectively isolated from Kubuqi desert, Inner Mongolia, China. The taxonomic characterization revealed Streptomyces as the predominant genus comprising 37 different species, along with the rare actinobacterial genus Lentzea. The methanolic extracts of 60.8% of strains exhibited potent antimicrobial activities against Staphylococcus aureus, Micrococcus luteus, Bacillus subtilis, Escherichia coli, Salmonella enterica, Saccharomyces cerevisiae and high to mild in vitro cytotoxicity against PC3 (prostate cancer) and A549 (lung carcinoma) cell lines. The metabolomics analysis by TLC, HPLC-UV/vis, HPLC-MS and NMR showed the presence of compounds with molecular weights ranging from 100 to 1000 Da. The scale-up fermentation of the prioritized anti-Gram-negative strain PU-KB10–4 (Streptomyces griseoviridis), yielded three pure compounds including; griseoviridin (1; 42.0 mgL− 1) with 20 fold increased production as compared to previous reports and its crystal structure as monohydrate form is herein reported for the first time, mitomycin C (2; 0.3 mgL− 1) and a new bacterial metabolite 4-hydroxycinnamide (3; 0.59 mgL− 1).ConclusionsThis is the first report of the bioprospecting and exploration of actinobacteria from Kubuqi desert and the metabolite 4-hydroxycinnamide (3) is first time isolated from a bacterial source. This study demonstrated that actinobacteria from Kubuqi desert are a potential source of novel bioactive natural products. Underexplored harsh environments like the Kubuqi desert may harbor a wider diversity of actinobacteria, particularly Streptomyces, which produce unique metabolites and are an intriguing source to develop medicinally valuable natural products.

Diversity and Bioactivity of Endophytic Actinobacteria Associated with Grapevines

Grapevine trunk diseases (GTDs) are a significant problem for New Zealand viticulture. Endophytic actinobacteria are of interest as potential biocontrol agents due to their ability to inhibit plant pathogens and improve plant growth. However, no studies have investigated the diversity of actinobacteria associated with grapevines in New Zealand vineyards and their bioactivity. Actinobacteria diversity in different ‘Sauvignon blanc’ vine tissues from three vineyards (conventional and organic management, and different vine ages) was assessed using different methods and media. Forty-six endophytic actinobacteria were isolated, with more isolates recovered from roots (n = 45) than leaves (n = 1) and shoot internodes (n = 0). More isolates were recovered from the organic (n = 21) than conventional (n = 8) vineyard, mature (25-year old; n = 21) than young (2-year old; n = 2) vines and using a tissue maceration technique (n = 40). Actinomycete Isolation Agar, International Streptomyces Project 2, and Starch Casein media were effective for actinobacteria isolation. Most of the isolates recovered belonged to Streptomyces, with one isolate identified as Mycolicibacterium. Forty isolates were assessed for antifungal activity and plant growth-promoting (PGP) characteristics. Of these, 13 isolates had antifungal activity against test GTD pathogens (Dactylonectria macrodidyma, Eutypa lata, Ilyonectria liriodendri, Neofusicoccum parvum, and N. luteum). Eighteen isolates exhibited more than one PGP trait; 25siderophore production (n = 25), phosphate solubilization (n = 6), and indole acetic acid production (n = 16). Two strains, Streptomyces sp. LUVPK-22 and Streptomyces sp. LUVPK-30, exhibited the best antifungal and PGP properties. This study revealed the diversity of culturable endophytic actinobacteria from grapevines in New Zealand vineyards and their biocontrol potential against GTD pathogens.

Actinobacteria Community and Their Antibacterial and Cytotoxic Activity on the Weizhou and Xieyang Volcanic Islands in the Beibu Gulf of China.

Weizhou Island and Xieyang Island are two large and young volcanic sea islands in the northern part of the South China Sea. In this study, high-throughput sequencing (HTS) of 16S rRNA genes was used to explore the diversity of Actinobacteria in the Weizhou and Xieyang Islands. Moreover, a traditional culture-dependent method was utilized to isolate Actinobacteria, and their antibacterial and cytotoxic activities were detected. The alpha diversity indices (ACE metric) of the overall bacterial communities for the larger island (Weizhou) were higher than those for the smaller island (Xieyang). A beta diversity analysis showed a more dispersive pattern of overall bacterial and actinobacterial communities on a larger island (Weizhou). At the order level, Frankiales, Propionibacteriales, Streptomycetales, Micrococcales, Pseudonocardiales, Micromonosporales, Glycomycetales, Corynebacteriales, and Streptosporangiales were the predominant Actinobacteria. A total of 22.7% of the OTUs shared 88%–95% similarity with some known groups. More interestingly, 15 OTUs formed a distinct and most predominant clade, and shared identities of less than 95% with any known families. This is the first report about this unknown group and their 16S rRNA sequences obtained from volcanic soils. A total of 268 actinobacterial strains were isolated by the culture-dependent method. Among them, 55 Streptomyces species were isolated, representing that 76.6% of the total. S. variabilis and S. flavogriseus were the most abundant. Moreover, some rare Actinobacteria were isolated. These included Micromonospora spp., Nocardia spp., Amycolatopsis spp., Tsukamurella spp., Mycobacterium spp., and Nonomuraea spp. Among them, eight Streptomyces spp. exhibited antibacterial activity against Bacillus cereus. Only three strains inhibited the growth of Escherichia coli. Four strains showed good activity against aquatic pathogenic bacterial strains of Streptococcus iniae. The cytotoxicity assay results showed that 27 strains (10.07%) exhibited cytotoxic activity against HeLa and A549 cell lines. Many actinobacterial strains with cytotoxic activity were identified as rare Actinobacteria, which illustrated that volcanic islands are vast reservoirs for Actinobacteria with promising antibacterial and cytotoxic activity. This study may significantly improve our understanding of actinobacterial communities on volcanic islands. The isolated Actinobacteria showed promising prospects for future use.

Community of Soil Actinobacteria in PTPN VI Oil Palm Plantation Jambi (Sumatra, Indonesia) Based on Amplicon Sequencing of 16S rRNA Gene

In Sumatra, Indonesia, increased oil palm production encourages land expansion for oil palm plantations. And soil Actinobacteria have a potential role in agriculture and plantations ecosystems. The use of fertilizer and herbicide affects soil microbial diversity, including Actinobacteria. This research analyzed and investigated the community composition and diversity of Actinobacteria in soils of oil palm plantations in Jambi Sumatra. Amplicon-based analysis of the 16S rRNA gene (V3-V4 hypervariable region) was used to amplify actinobacterial full-length 16S sequences. The V3-V4 actinobacterial specific 16S rRNA gene sequencing was done using Next-Generation Sequencing. This study confirmed that actinobacterial specific 16S rRNA gene primer could amplify the actinobacterial 16S rRNA gene. Frankiales dominated the community composition of soilborne Actinobacteria. The diversity and community composition of soilborne Actinobacteria were not significantly affected by the interaction between fertilization and weed treatments. Furthermore, the use of NPK fertilizer significantly affected the abundance of Kineosporiales, whose abundance increased with the increasing concentration of NPK fertilizer. The interaction between fertilization and weeding treatments in the oil palm plantations has no impact on soil Actinobacteria's community composition and diversity.

Phylogenetic diversity of Actinobacteria from Momela soda lakes, Arusha National Park, Tanzania

The Momela soda lakes consist of seven small, hypersaline, alkaline lakes, situated in the East African rift valley at Arusha National Park, Tanzania. The lakes are fed by separate underground water sources with slightly varying mineral contents resulting in colour variation and supporting different kinds of prokaryotic and eukaryotic species. In this study, the diversity of Actinobacteria in surface water and sediments of five Lakes were investigated using culture-dependent and culture-independent molecular techniques. A total of 34 out of 112, and 13 out of 85, representatives of Actinobacteria isolates and clones, respectively, were selected for gene sequencing using the CD-HIT program. Analysis of their 16S rRNA gene sequences displayed the presence of species affiliated to 15 different genera, namely Mycobacterium, Rhodococcus, Microbacterium, Isoptericola, Dietzia, Leucobacter, Jonesia, Nesterenkonia, Micrococcus, Streptomyces, Hoyosella, Norcadiopsis, Cellulomonas, Bogoriella, and Agromyces. The results showed 5 and 12 putative new Actinobacteria isolates and clones, respectively. This is the first report of isolation of bacteria from the genus Mycobacterium from a soda lake globally, as well as the genera Hoyosella, Isoptericola, Jonesia, Micrococcus, Leucobacter and Agromyces from a soda lake in East Africa. Because Actinobacteria are known as a source of biotechnologically important compounds, the species revealed set a platform to search for novel bioactive compounds.

Evaluation of antimicrobial and antiproliferative activities of Actinobacteria isolated from the saline lagoons of northwestern Peru.

Extreme environments Morrope and Bayovar Salt lagoons, several ecosystems and microhabitats remain unexplored, and little is known about the diversity of Actinobacteria. We suggest that the endemic bacteria present in this extreme environment is a source of active molecules with anticancer, antimicrobial, and antiparasitic properties. Using phenotypic and genotypic characterization techniques, including 16S rRNA sequencing, we identified these bacteria as members of the genera Streptomyces, Pseudonocardia, Staphylococcus, Bacillus, and Pseudomonas. Actinobacteria strains were found predominantly. Phylogenetic analysis revealed 13 Actinobacteria clusters of Streptomyces, the main genus. Three Streptomycetes, strains MW562814, MW562805, and MW562807 showed antiproliferative activities against three tumor cell lines: U251 glioma, MCF7 breast, and NCI-H460 lung (non-small cell type); and antibacterial activity against Staphylococcus aureus ATCC 6538, Escherichia coli ATCC 10536, and the multidrug resistant Acinetobacter baumannii AC-972. The antiproliferative activities (measured as total growth inhibition [TGI]) of Streptomyces sp. MW562807 were 0.57 μg/mL, for 0.61 μg/mL, and 0.80 μg/mL for glioma, lung non-small cell type, and breast cancer cell lines, respectively; the methanolic fraction of the crude extract showed a better antiproliferative activity and could inhibit the growth of (U251 (TGI = 38.3 μg/mL), OVCAR-03 (TGI = 62.1 μg/mL), and K562 (TGI = 81.5 μg/mL)) of nine tumor cells types and one nontumor cell type. Extreme enviroments, such as the Morrope and Bayovar Salt saloons are promising sources of new bacteria, whose compounds may be useful for treating various infectious diseases or even some types of cancer.

Existence in cellulose shelters: industrial and pharmaceutical leads of symbiotic actinobacteria from ascidian Phallusia nigra, Andaman Islands.

The diversity of actinobacteria associated with marine ascidian Phallusia nigra from Andaman Islands was investigated. A total of 10 actinobacteria were isolated and based on the biochemical and molecular characterization, the isolates were assigned to 7 different actinobacterial genera. Eight putatively novel species belonging to genera Rhodococcus, Kineococcus, Kocuria, Janibacter, Salinispora and Arthrobacter were identified based on 16S rDNA sequence similarity with the NCBI database. The organic extracts of ten isolates displayed considerable bioactivity against test pathogens, which were Gram-positive and Gram-negative in nature. PCR-based screening for type I and type II polyketide synthases (PKS-I, PKS-II) and nonribosomal peptide synthetases (NRPS) revealed that, 10 actinobacterial isolates encoded at least one type of polyketide synthases biosynthesis gene. Majority of the isolates found to produce industrially important enzymes; amylase, protease, gelatinase, lipase, DNase, cellulase, urease, phosphatase and L-asparaginase. The present study emphasized that, ascidians are a prolific resource for novel bioactive actinobacteria with potential for novel drug discovery. This result expands the scope to functionally characterize the novel ascidian associated marine actinobacteria and their metabolites could be a source for the novel molecules of commercial interest.

A Simple Culture Method Enhances the Recovery of Culturable Actinobacteria From Coastal Sediments.

Molecular methods revealed that the majority of microbes in natural environments remains uncultivated. To fully understand the physiological and metabolic characteristics of microbes, however, culturing is still critical for microbial studies. Here, we used bacterial community analysis and four culture media, namely, traditional marine broth 2216 (MB), water extracted matter (WEM), methanol extracted matter (MEM), and starch casein agar (SCA), to investigate the diversity of cultivated bacteria in coastal sediments. A total of 1,036 isolates were obtained in pure culture, and they were classified into five groups, namely, Alphaproteobacteria (52.51%), Gammaproteobacteria (23.26%), Actinobacteria (13.32%), Firmicutes, and Bacteroidetes. Compared to other three media, WEM recovered a high diversity of actinobacteria (42 of 63 genotypes), with Micromonospora and Streptomyces as the most cultivated genera. Amplicon sequencing of the bacterial 16S ribosomal RNA (rRNA) gene V3–V4 fragment revealed eight dominant groups, Alphaproteobacteria (12.81%), Gammaproteobacteria (20.07%), Deltaproteobacteria (12.95%), Chloroflexi (13.09%), Bacteroidetes (8.28%), Actinobacteria (7.34%), Cyanobacteria (6.20%), and Acidobacteria (5.71%). The dominant members affiliated to Actinobacteria belonged to “Candidatus Actinomarinales,” “Candidatus Microtrichales,” and Nitriliruptorales. The cultivated actinobacteria accounted for a small proportion (<5%) compared to the actinobacterial community, which supported that the majority of actinobacteria are still waiting for cultivation. Our study concluded that WEM could be a useful and simple culture medium that enhanced the recovery of culturable actinobacteria from coastal sediments.

Diversity of actinobacteria in sediments of Qaidam Lake and Qinghai Lake, China.

Using 16S rRNA gene analysis and high-throughput, the diversity and community structure of actinobacteria in the sediments of Qaidam Lake and Qinghai Lake with different salinity and alkalinity in Qinghai-Xizang Plateau were studied, and the differences of actinobacteria community structure and their relationship with environmental factors were discussed. A total of 77 genera belonging to actinobacteria were found in the samples, of which 31 genera were found in the sediment samples of Qaidam Lake with 19 genera being dominant genera, such as Actinomycetes, Corynebacterium, Morella, Bifidobacterium, and 69 genera were found in the sediment samples of Qinghai Lake with 17 genera becoming dominant, such as Ilumattalaer, Actinotalea, Aquihaans and so on. The correlation analysis of environmental factors and community showed that the community structure of the two salt lakes was mainly affected by total salinity, total organic carbon) (TOC) and CO32-, among which TOC was the most influential factor. The functional differences of metabolic pathway enrichment analysis (KEGG) showed that there was a high abundance of metabolic-related functions in the two salt lakes. There were significant differences in the biosynthesis of energy metabolism and other secondary metabolites between the two salt lakes, which may be the main reason for the difference of actinomycete community. The results show that the actinobacteria diversity was rich in the plateau salt lakes, and affected by a variety of physicochemical factors. In addition, there were a large number of unculturable actinobacteria in the sediment, which provides a theoretical basis for the excavation and utilization of actinobacteria resources in salt lakes.

Isolation and characterization of culturable actinobacteria associated with Polytrichum strictum (Galindez Island, the maritime Antarctic)

The main objective of the study is the evaluation of the diversity of actinobacteria associated with Polytrichum strictum — dominant species of widespread Antarctic Тall moss turf subformation and their characteristics as the producers of biologically active compounds. The actinobacterial isolates were isolated by direct inoculation, phenol pretreatment, and heated treatment. The cultural properties of the isolates were evaluated using diagnostic media. The antimicrobial activity of the isolates was determined by the point inoculations method. The phylogenetic analysis was based on sequence analysis of the 16S rRNA gene. The biosynthetic genes screening was performed using polymerase chain reaction. A total of 23 actinobacterial isolates associated with P. strictum were isolated, the four identified genera being Streptomyces (7 isolates), Micromonospora (14 isolates), Kribbella (1 isolate), and Micrococcus (1 isolate). Eight psychrotrophic strains of all identified genera were identified. The optimal pH values for all isolates were in the range 6–10. Four isolates grew on the medium with 7.5% NaCl. A significant number of the isolates showed a wide range of enzymatic activities. Antagonists of a wide range of pathogenic microorganisms were found, including against multidrug-resistant strain of Candida albicans and Methicillin-resistant Staphylococcus aureus. Some strains were active against phytopathogenic bacteria, namely three strains against Erwinia amylovora, one strain against Agrobacterium tumefaciens, and one strain against Pectobacterium carotovorum. More than half of the isolates showed antifungal activity against Fusarium oxysporum and Aspergillus niger. The biosynthetic genes involved in synthesizing a wide range of bioactive compounds were found in more than 80% of isolates. Antarctic actinobacteria isolated in this study demonstrate potential as the producers of a wide range of biologically active compounds. Further studies of these actinobacteria may lead to the identification of previously unknown biologically active compounds.

Diversity of Actinobacteria Isolated from Date Palms Rhizosphere and Saline Environments: Isolation, Identification and Biological Activity Evaluation.

The diversity of cultural Actinobacteria in two types of Algerian Sahara environments, including saline environments and date palms rhizosphere, was investigated. In this study, a total of 40 strains of actinomycetes was isolated from different soil samples, using a rehydration and centrifugation method. Molecular identification, based on 16S rRNA gene sequence analysis, revealed that these isolates were affiliated to six clusters corresponding to eight genera, including Streptomyces, Nocardiopsis, Saccharopolyspora, Actinomadura, Actinocorallia, Micromonospora, Couchioplanes, and Planomonospora. A taxonomic analysis, based on the morphological, physiological, biochemical, and molecular investigation, of selected strains, which belong to the rare Actinobacteria, was undertaken. Four strains (CG3, A111, A93, and A79) were found to form distinct phyletic lines and represent new actinobacterial taxa. An assessment of antimicrobial proprieties of the 40 obtained actinomycetes strains, showed moderate to strong antimicrobial activities against fungi and bacteria. This study demonstrated the richness of Algerian Sahara with rare Actinobacteria, which can provide novel bioactive metabolites, to solving some of the most challenging problems of the day, such as multi-drug resistance.