Genome-Guided Discovery of Natural Products through Multiplexed Low-Coverage Whole-Genome Sequencing of Soil Actinomycetes on Oxford Nanopore Flongle

Short-read sequencing of GC-rich genomes such as those from actinomycetes results in a fragmented genome assembly and truncated biosynthetic gene clusters (often 10 to >100 kb long), which hinders our ability to understand the biosynthetic potential of a given strain and predict the molecules that can be produced. The current study demonstrates that contiguous DNA assemblies, suitable for analysis of BGCs, can be obtained through low-coverage, multiplexed sequencing on Flongle, which provides a new low-cost workflow ($30 to 40 per strain) for sequencing actinomycete strain libraries.

Isolation of Novel Vincristine and Vinblastine Producing Streptomyces Species from Catharanthus Roseus Rhizospheric Soil

Microorganisms could be used as efficient tools to protect high value therapeutic plants against overexploitation and climate change. This work aimed to isolate alkaloids producing endophytic and rhizospheric soil actinomycetes and fungi of Catharanthus roseus. From a total of eleven actinomycetes and eight fungi strains isolated by dilution and plate methods, six telluric actinomycetes were revealed to produce alkaloids according to the precipitation test of their extracts. Revelation by Thin Layer Chromatography method using vinblastine and vincristine standards on the basis of frontal reference values showed that the strain SC8 and the vinblastine, the strain SC7 and the vincristine displayed the same frontal references (0,89 and 0,88, respectively). Whole genome sequencing method showed that both strains belong to the genus Streptomyces with novel species.Moreover, metabolic pathways analysis from their genomes allowed to detect three enzymes involved in the biosynthesis of terpenoid backbone leading to that of terpenoid indole alkaloids.

ISOLATION, CHARACTERIZATION AND ANTIBACTERIAL SREENING OF ANTIBIOTICS PRODUCED FROM STREPTOMYCES ISOLATED FROM DUMPSITE SOILS IN ILORIN, NORTH CENTRAL NIGERIA

Antibiotics are one of the most exploited metabolites produced by soil actinomycetes. This study isolated fifteen actinomycetes (A1 – A15) from dumpsite soils within Ilorin metropolis & screened them for antibacterial activity. Isolates were identified with morphology & biochemical characteristics.Their activity against clinical bacteria (Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae & Staphylococcus aureus) was determined. Their bioactive metabolites after fermentation was assayed for by agar well diffusion & compared with reference antibiotics. Molecular analysis of two most active isolates was done. The most active metabolite was subjected to GCMS. All isolates were identified as Streptomyces, 7 isolates exhibited activity against 3 test bacteria with highest (10.5mm±0.35) by Streptomyces griseoplanus while S. aureus demonstrated total resistance to all isolates. Secondary activity revealed 7 of the metabolites as effective against the bacteria with highest activity (28.5±1.04mm) by S. sparsogenes showing similar activity with Cefuroxime (28.01±0.01mm). The two most active isolates were Streptomyces griseoplanus strain NR725RL-ISP 5009 & Streptomyces sparsogenes strain NBRC 1308616S & RNA nucleotide similarity revealed close phylogenic relationship. GC-MS revealed10 compounds in S. sparsogenes strain NBRC 1308616S metabolite. Streptomyces from dumpsite soils within Ilorin produced bioactive compounds against clinical test bacteria and thus could be potential sources of antibiotics.

Effect of integrated weed management on groundnut (Arachis hypogea)

An experiment on integrated weed management in groundnut (Arachis hypogea) was conducted at Department of Agronomy during 2009-10. Ten treatments which included three herbicides viz., Pendimethalin, Quizolofop ethyl, Imazethapyr with mechanical weeding were studied in Randomized Block Design. Complete weed free condition recorded highest dry pod yield (1786 kgha-1). Pre-emergence application of Pendimethalin 1.0 kg a.i./ha followed by one hand weeding at 15 days after sowing, recorded 10.8 pods/plant as against 4.97 pods/plant and 60.0 nodule per plant as against 37.5 in unweeded control. Preemergence application of Pendimethalin @ 1.0 kg a.i./ha followed by post-emergence Imazethapyr @ 75 g a.i./ha at 15 days after sowing increased pod yield (1255 kgha-1), shelling % and 100 kernal weight. Application of Pendimethalin recorded increased soil fungal count 16.0X104 cfu g-1, soil actinomycetes count 15.67X106 cfu g-1 and soil bacterial count 20.33X10 cfu g-1 compared to unweeded control.

ISOLATION OF POTASSIUM SOLUBILIZING ACTINOMYCETES FROM CERAMIC INDUSTRY SOILS

Soil fertility and plant nutrition require an adequate management of essential macronutrients such as potassium (K) is mandatory for plant development. Potassium replenishment, particularly in smallholder agriculture, remains a challenge as it is mainly fertilizer dependent. While the user of soluble mineral potassium fertilizers is the obvious best means to combat potassium deficiency in soil, they were limited by high cost of fertilizers and availability at farmer's level. This research is to isolate and select potassium solubilizing soil Actinomycetes from ceramic industry soils. 22 Actinomycetes isolates were inoculated on Aleksandrov agar supplemented with 0.5% potassium aluminium silicate, isolates which gave the high ratio of clear zone were selected. Out of 22 Actinomycetes Isolates two (KSA 09 and KSA 16) were selected which gave highest solubilization in liquid medium by solubilizing insoluble potassium source i.e. feldspar. This two strain selected for further studies for future prospectus.

Biorational insectoacaricides based on avermectins to protect grapes

The article presents an assessment of the biological effectiveness of biorational insectoacaricides based on abamectin and emamectin benzoate – metabolites of soil actinomycetes, to protect grapes from pests. We studied the effectiveness of new drugs: Mekar, ME (18 g/l abamectin) and Mabet, EC (18 g/l abamectin) against Schizotetranychus pruni; Yunona, ME (50 g/l emamectin benzoate), Emakleim, VRG (50 g/l emamectin benzoate) and Proclame Fit, WDG (400 g/kg lufenuron + 50 g/kg emamectin) against Lobesia botrana in the Krasnodar Region. According to the research results, the drugs Mekar, ME (18 g/l), Yunona, ME (50 g/l) and Proclame Fit, WDG (400 g/kg + 50 g/kg) are included in the State Catalog of Pesticides and Agrochemicals Permitted for Use on the territory of the Russian Federation and can be used in biologized and adaptively integrated grape protection systems.