The lack of new antibiotics in the pharmaceutical pipeline guides more and more researchers to leave the classical isolation procedures and to look in special niches and ecosystems. Bioprospecting of extremophilic Actinobacteria through mining untapped strains and avoiding resiolation of known biomolecules is among the most promising strategies for this purpose. With this approach, members of acidtolerant, alkalitolerant, psychrotolerant, thermotolerant, halotolerant and xerotolerant Actinobacteria have been obtained from respective habitats. Among these, little survey exists on the diversity of Actinobacteria in arid areas, which are often adapted to relatively high temperatures, salt concentrations, and radiation. Therefore, arid and desert habitats are special ecosystems which can be recruited for the isolation of uncommon Actinobacteria with new metabolic capability. At the time of this writing, members of Streptomyces, Micromonospora, Saccharothrix, Streptosporangium, Cellulomonas, Amycolatopsis, Geodermatophilus, Lechevalieria, Nocardia, and Actinomadura are reported from arid habitats. However, metagenomic data present dominant members of the communities in desiccating condition of areas with limited water availability that are not yet isolated. Furthermore, significant diverse types of polyketide synthase (PKS) and non-ribosomal peptide synthetase (NRPS) genes are detected in xerophilic and xerotolerant Actinobacteria and some bioactive compounds are reported from them. Rather than pharmaceutically active metabolites, molecules with protection activity against drying such as Ectoin and Hydroxyectoin with potential application in industry and agriculture have also been identified from xerophilic Actinobacteria. In addition, numerous biologically active small molecules are expected to be discovered from arid adapted Actinobacteria in the future. In the current survey, the diversity and biotechnological potential of Actinobacteria obtained from arid ecosystems, along with the recent work trend on Iranian arid soils, are reported.

More than 70 species of halotolerant and halophilic actinomycetes belonging to at least 24 genera have been validly described. Halophilic actinomycetes are a less explored source of actinomycetes for discovery of novel bioactive secondary metabolites. Degradation of aliphatic and aromatic organic compounds, detoxification of pollutants, production of new enzymes and other metabolites such as antibiotics, compatible solutes and polymers are other potential industrial applications of halophilic and halotolerant actinomycetes. Especially new bioactive secondary metabolites that are derived from only a small fraction of the investigated halophilic actinomycetes, mainly from marine habitats, have revealed the huge capacity of this physiological group in production of new bioactive chemical entities. Combined high metabolic capacities of actinomycetes and unique features related to extremophilic nature of the halophilic actinomycetes have conferred on them an influential role for future biotechnological applications.

Plant growth promoting (PGP) bacteria are involved in various interactions known to affect plant fitness and soil quality, thereby increasing the productivity of agriculture and stability of soil. Although the potential of actinobacteria in antibiotic production is well-investigated, their capacity to enhance plant growth is not fully surveyed. Due to the following justifications, PGP actinobacteria (PGPA) can be considered as a more promising taxonomical group of PGP bacteria: (1) high numbers of actinobacteria per gram of soil and their filamentous nature, (2) genome dedicated to the secondary metabolite production (~5 to 10 %) is distinctively more than that of other bacteria and (3) number of plant growth promoter genera reported from actinobacteria is 1.3 times higher than that of other bacteria. Mechanisms by which PGPA contribute to the plant growth by association are: (a) enhancing nutrients availability, (b) regulation of plant metabolism, (c) decreasing environmental stress, (d) control of phytopathogens and (e) improvement of soil texture. Taxonomical and chemical diversity of PGPA and their biotechnological application along with their associated challenges are summarized in this paper.

The cell-free extracts of a landomycin E-producing strain, Streptomyces globisporus 1912-2, were shown to contain a low-molecular-weight compound that, like A-factor, restored the landomycin E and streptomycin biosynthesis and sporulation of the defective mutants S. globisporus 1912-B2 and S. griseus 1439, respectively. The compound was purified by thin layer chromatography and HPLC. It had an absorption maximum at λmax=245 nm and a molecular mass of m/z 244. On the basis of NMR spectroscopy ((1)H, (13)C, HSQC, HMBC, COSY and NOE) the chemical structure of the compound was elucidated as 6-benzyl-3-eth-(Z)-ylidene-1-methyl-piperazine-2,6-dione ((L)-N-methylphenylalanyl-dehydrobutyrine diketopiperazine (MDD)). The sequences of arpA genes in S. globisporus 1912-2 and S. griseus NBRC 13350 are highly conserved. An explanation for the observed biological activity of MDD was proposed.

Natural products (NPs) are a valuable source in the food, pharmaceutical, agricultural, environmental, and many other industrial sectors. Their beneficial properties along with their potential toxicities make the detection, determination or quantification of NPs essential for their application. The advanced instrumental methods require time-consuming sample preparation and analysis. In contrast, biosensors allow rapid detection of NPs, especially in complex media, and are the preferred choice of detection when speed and high throughput are intended. Here, we review diverse biosensors reported for the detection of NPs. The emerging approaches for improving the efficiency of biosensors, such as microfluidics, nanotechnology, and magnetic beads, are also discussed. The simultaneous use of two detection techniques is suggested as a robust strategy for precise detection of a specific NP with structural complexity in complicated matrices. The parallel detection of a variety of NPs structures or biological activities in a mixture of extract in a single detection phase is among the anticipated future advancements in this field which can be achieved using multisystem biosensors applying multiple flow cells, sensing elements, and detection mechanisms on miniaturized folded chips.

Problem The lately emerged SARS-CoV-2 infection, which has put the whole world in an aberrant demanding situation, has generated an urgent need for developing effective responses through artificial intelligence (AI). Aim This paper aims to overview the recent applications of machine learning techniques contributing to prevention, diagnosis, monitoring, and treatment of coronavirus disease (SARS-CoV-2). Methods A progressive investigation of the recent publications up to November 2020, related to AI approaches towards managing the challenges of COVID-19 infection was made. Results For patient diagnosis and screening, Convolutional Neural Network (CNN) and Support Vector Machine (SVM) are broadly applied for classification purposes. Moreover, Deep Neural Network (DNN) and homology modeling are the most used SARS-CoV-2 drug repurposing models. Conclusion While the fields of diagnosis of the SARS-CoV-2 infection by medical image processing and its dissemination pattern through machine learning have been sufficiently studied, some areas such as treatment outcome in patients and drug development need to be further investigated using AI approaches.

A novel streptomycete, designated strain HM 35 T , was isolated from soil in Isfahan city, Iran. Strain HM 35 T produced a branched substrate mycelium and aerial hyphae that developed into short, compact, spiral spore chains with grey rugose spores at the tips of the aerial hyphae. On some media, these spirals coalesced into dark masses of spores with age. Whole-cell hydrolysates of strain HM 35 T contained LL-diaminopimelic acid, glucose and ribose. Phospholipids detected were phosphatidylglycerol, phosphatidylinositol, phosphatidylethanolamine, phosphatidylinositol mannosides, hydroxy-phosphatidylethanolamine, lyso-phosphatidylethanolamine and hydroxy-lyso-phosphatidylethanolamine. MK-9(H 4 ), ) and MK-9(H 8 ) were the predominant menaquinones. The major fatty acids were iso-and anteisobranched components. The chemotaxonomic characteristics of the novel isolate matched those described for members of the genus Streptomyces. Based on 16S rRNA gene sequence analysis, strain HM 35 T showed highest similarity to Streptomyces rapamycinicus NRRL 5491 T (99.2 %), Streptomyces violaceusniger DSM 40563 T (99.1 %), Streptomyces javensis DSM 41764 T (99.1 %) and Streptomyces yogyakartensis DSM 41766 T (99.1 %). The novel strain formed a distinct monophyletic line within the 16S rRNA gene sequence tree. The level of DNA-DNA relatedness between strain HM 35 T and the type strain of S. rapamycinicus was 72.7 %. Strain HM 35 T showed the typical morphology found among members of the S. violaceusniger/ Streptomyces hygroscopicus group but could be clearly differentiated from closely related species based on other phenotypic markers. Phenotypic and genotypic data thus indicate that strain HM 35 T represents a novel species of the genus Streptomyces, for which the name Streptomyces iranensis is proposed. The type strain is HM 35 T (5DSM 41954 T 5CCUG 57623 T ).The genus Streptomyces was proposed by Waksman & Henrici (1943) to accommodate aerobic, spore-forming actinomycetes. The genus comprises Gram-positive bacteria that have a high DNA G+C content (69-73 mol%), contain LL-diaminopimelic acid in the peptidoglycan and lack diagnostic sugars in whole-cell hydrolysates. More than 500 Streptomyces species have been described, the largest number of any bacterial genus (Euzéby, 2009). Although molecular systematic data show that the genus is clearly over-speciated (Lanoot et al., 2004), other polyphasic studies based on a combination of genotypic and phenotypic features continue to identify novel species and indicate that the genus Streptomyces as a whole is underspeciated (Kim & Goodfellow, 2002). Members of novel Streptomyces species are in demand as a source of new, commercially significant, bioactive compounds (Berdy, 1995;Fiedler et al., 2005).The Microbial Biotechnology Laboratory of the University of Tehran has been interested in isolating actinomycetes from Iranian soils, with the purpose of selecting strains with potential for biotechnological application.The aim of the present study was to classify a Streptomyceslike strai...

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