Methods and systems for isolating and identifying nucleic acid from a plurality of microorganisms and viruses

1. A method for isolating nucleic acid from a plurality of microorganisms or viruses, comprising:

a. obtaining a sample from a plurality of microorganisms or viruses comprising:

a. obtaining a sample comprising nucleic acid from a plurality of microorganisms or viruses,

b. subjecting the sample to a serial centrifugation procedure comprising,

i. performing a first centrifugation under conditions that subject the nucleic acid in the sample to a force of between around 8,000 to around 12,000 ×g,

ii. isolating a first supernatant and a first pellet,

iii. performing a second centrifugation of said first supernatant under conditions that subject the nucleic acid in the sample to a force of between around 22,000 to around 35,000 ×g, in the presence or absence of a liquid centrifugation medium, and

iv. isolating a second supernatant and a second pellet, wherein said nucleic acid is isolated from the plurality of microorganisms or viruses, wherein the sample is collected from a host organism comprising said plurality of microorganisms or viruses, and wherein the host organism is a mammal.

2. The method of claim 1 , wherein the sample is blood, serum, tissue, plasma, saliva, fecal matter, urine, cerebrospinal fluid, soil, or water.

3. A method for isolating nucleic acid from a plurality of microorganisms or viruses, comprising:

a. obtaining a sample comprising nucleic acid from a plurality of microorganisms or viruses,

b. subjecting the sample to a serial centrifugation procedure comprising,

i. performing a first centrifugation is performed under conditions that subject the nucleic acid in the sample to a force around 8,000 to around 12,000 ×g,

ii. isolating a first supernatant and a first pellet,

iii. performing a second centrifugation of said first supernatant under conditions that subject the nucleic acid in the sample to a force of between around 22,000 ×g to around 35,000 ×g, in the presence or absence of a liquid centrifugation medium and

iv. isolating a second supernatant and a second pellet, wherein said nucleic acid is isolated from the plurality of microorganisms or viruses, wherein the sample is blood, serum, tissue, plasma, saliva, fecal matter, soil, or water.

4. The method of claim 3 wherein the density centrifugation medium has a density of between 1.1 and 1.5 grams per cubic centimeter.

5. The method of claim 3 , wherein the density centrifugation medium is sucrose or OptiPrep™.

6. The method of claim 1 , wherein nucleic acid in the sample from the host organism is removed by exposing any of the second supernatant, or the first or second pellet, to one or more nucleases.

7. A method for isolating nucleic acid from a plurality of microorganisms or viruses, comprising:

a. obtaining a sample comprising nucleic acid from a plurality of microorganisms or viruses,

b. subjecting the sample to a serial centrifugation procedure comprising,

i. performing a first centrifugation under conditions that subject the nucleic acid in the sample to a force of between around 8,000 to around 12,000 ×g,

ii. isolating a first supernatant and a first pellet,

iii. performing a second centrifugation of said first supernatant under conditions that subject the nucleic acid in the sample to a force of between around 22,000 to around 35,000 ×g, in the presence or absence of a liquid centrifugation medium, and

iv. isolating a second supernatant and a second pellet,

wherein said nucleic acid is isolated from the plurality of microorganisms or viruses wherein the sample is collected from a host organism comprising said plurality of microorganisms or viruses, and

wherein nucleic acid in the sample from the host organism is removed by exposing any of the second supernatant, or the first or second pellet, to one or more DNA or RNA nucleases.

8. The method of claim 1 , wherein the nucleic acid is DNA or RNA.

9. A method for isolating nucleic acid from a plurality of microorganisms or viruses, comprising:

a. isolating nucleic acid from a plurality of microorganisms or viruses

b. subjecting the sample to a serial centrifugation procedure comprising,

i. performing a first centrifugation under conditions that subject the nucleic acid in the sample to a force of between around 8,000 to around 12,000 ×g,

ii. isolating a first supernatant and a first pellet,

iii. performing a second centrifugation of said first supernatant under conditions that subject the nucleic acid in the sample to a force of between around 22,000 to around 35,000 ×g, in the presence or absence of a liquid centrifugation medium, and

iv. isolating a second supernatant and a second pellet,

wherein said nucleic acid is isolated from the plurality of microorganisms or viruses wherein the sample is blood, serum, tissue, plasma, saliva, fecal matter, soil, or water,

wherein the density centrifugation medium is sucrose or OptiPrep™, wherein the one or more nucleases comprises at least one of a DNA or a RNA nuclease, and wherein the nucleic acid is DNA or RNA.

10. A method for preparing a library of nucleic acid from a plurality of viruses or other microorganisms, comprising:

a. obtaining a biological sample comprising a plurality of viruses or other microorganisms from a host organism,

b. subjecting the biological sample to a serial centrifugation procedure comprising,

i. centrifuging the sample under conditions that subject the sample to a force of about 8,000 to about 12,000 ×g,

ii. isolating a first supernatant and a first pellet,

iii. centrifuging said first supernatant under conditions that subject the sample to a force of about 22,000 to about 30,000 ×g, or through a liquid centrifugation medium,

iv. isolating a second supernatant and a second pellet, and

a. removing nucleic acid in the sample derived from the host organism by exposing any of the second supernatant, or the first or second pellet, to nuclease digestion, and

b. sequencing DNA or RNA of the second supernatant, or the first or second pellet, to generate a library of nucleic acids from said plurality of microorganisms or viruses present in the biological sample.

11. A method for isolating and identifying mitochondrial nucleic acid from a plurality of microorganisms present in a sample, comprising:

a. obtaining a biological sample from a host organism that comprises a plurality of microorganisms,

b. isolating nucleic acid from the sample, wherein the isolating step is performed to preferentially isolate circular nucleic acid species comprising mitochondrial DNA,

c. preparing a library of DNA from the isolated nucleic acids and sequencing members of the library, and

d. comparing the sequences present in the library to a database comprising mitochondrial genomes, or parts thereof, in order to identify microorganisms present in the sample.

12. The method of claim 11 , wherein isolating nucleic acid from a host organism comprises

a. centrifuging the sample under conditions that subject the sample to a force of about 8,000 to about 12,000 ×g,

b. isolating a supernatant and a pellet, and

c. preferentially isolating circular nucleic acid from the pellet or the supernatant.

13. The method of claim 12 , wherein preferentially isolating the circular nucleic acid comprises separation using column chromatography or cesium chloride density gradient centrifugation.

14. A method comprising:

obtaining a biological sample from a host;

obtaining nucleic acid sequence information from the biological sample;

determining a first portion of the nucleic acid sequence information that corresponds to a known host sequence;

translating a second portion of the nucleic acid sequence information into amino acid sequence information in at least one open reading frame;

determining a plurality of amino acid sequences based on the nucleic acid sequence information;

removing, from the nucleic acid sequence information, a first portion of the nucleic acid sequence information so as to provide the second portion of the nucleic acid sequence information;

curating a database comprising a plurality of entries, wherein each entry comprises respective microbe amino acid sequences, wherein curating the database comprises ignoring or removing at least a portion of the entries corresponding to redundant sequence information, wherein the redundant sequence information is similar to at least one other entry at a similarity level greater than a threshold similarity level;

comparing each amino acid sequence of the plurality of amino acid sequences to the curated database and

determining, based on the comparison, with at least one corresponding confidence level that at least one microbe is present in the biological sample

wherein a nucleic acid comprising the nucleic acd sequence information is obtained by subjecting the sample to a serial centrifugation procedure comprising,

a. centrifuging the sample under conditions that subject the sample to a force of about 8,000 to about 12,000 ×g,

b. isolating a first supernatant and a first pellet,

c. centrifuging said first supernatant under conditions that subject the sample to a force of about 22,000 to about 30,000 ×g, in the presence or absence of a liquid centrifugation medium, and

d. isolating a second supernatant and a second pellet comprising said nucleic acid.

15. The method of claim 14 , wherein the host is a mammal.

16. The method of claim 14 , wherein the biological sample comprises at least one of: water, soil, air, a tissue, a biological fluid, feces, or another product or byproduct from the host, and wherein obtaining the nucleic acid sequence information comprises obtaining the nucleic acid sequence information from the water, soil, air, tissue, biological fluid, feces, or another product or byproduct.

17. The method of claim 14 , wherein the nucleic acid sequence information comprises a ribonucleic acid.

18. The method of claim 14 , wherein obtaining nucleic acid sequence information from the biological sample comprises carrying out an unbiased polymerase chain reaction-free method.

19. The method of claim 14 , wherein the threshold similarity level is between ninety and ninety five percent nucleic acid sequence similarity.

20. The method of claim 14 , wherein the at least one microbe comprises a eukaryotic parasite.

21. The method of claim 14 , wherein the at least one microbe comprises bacteria, virus, or eukaryotic pathogen.