Metagenomic library and natural product discovery platform

Example 1

Modeling to Establish Optimum Metagenomic Library Parameters

[0417]The present invention is based, in part, on the inventor's discovery of metagenomic library parameters that enable in silico natural product discovery. The authors hypothesized that prior attempts to generate metagenomic libraries that would be useful for MGC discovery had failed by creating libraries that either i) failed to produce sufficiently long assemblies due to overly-complex DNA mixtures, or ii) failed to capture meaningful diversity within an environmental sample, due to the selection of only a few cells / cosmids for sequencing. That is, prior attempts had either not taken sufficient steps to reduce complexity, or had reduced complexity so much that it failed to capture the diversity of the sample.

[0418]As an initial step, the inventors analyzed the rate of MGC discovery with libraries of different N50 lengths. A variety of digital metagenomic libraries (DML) from samples of similar complexity were se

Example 2

Modeling to Establish Optimum Pooling Parameters

[0422]The present disclosure teaches methods of pooling clones from environmental samples into separate silos as a way to reduce complexity of metagenomic libraries for subsequent assembly. Pooling also allows for greater sampling of the environmental sample, and for more efficient use of the sequencer's bandwidth and can result in larger overall libraries per run. In order to determine the optimal level of pooling to produce DMLs for natural product discovery, a series of simulations were conducted.

[0423]In order to generate simulated sequencing and sequencing assembly of pools of cosmids of different sizes (1, 5, 10, 100, 200, 6,000, 12,000, and 60,000 cosmids), raw paired-end fasq (Illumina) data generated from multiple empirically sequenced metagenomic libraries of different sizes were concatenated to yield the desired simulated number of cosmids. The raw fastq files for these simulated pools were first trimmed using bbduk fr

Example 3

Preparation of Metagenomic Libraries

Collection

[0428]Approximately 1 kg of soil sample from a private field was collected and rocks, branches, and other non-soil matter were removed by passing the soil through a 2 mm wire sieve. DNA was extracted from ˜250 g of soil by first adding 300 mL of a CTAB-based lysis buffer (100 mM Tris-HCl, 100 mM EDTA, 1.5M NaCl, 1%(w / v) CTAB, 2%(w / v) SDS, pH 8.0), followed by incubation at 70° C. for 2 h with consistent inversion to mix. The sample was centrifuged at 4,000 g for 20 min. at 4° C. Supernatant was transferred to a clean bottle and centrifuged a second time at 4,000 g for 20 min. at 4° C. The resulting lysate was transferred to a new bottle and 0.7 volumes of isopropanol was added and gently mixed for 30 min. Precipitated DNA was pelleted by two rounds of centrifugation at 4,000 g for 30 min. at 4° C., washed with 70% ethanol between the first and second centrifugation. The supernatant was discarded, the DNA pellet was allowed to d