Parsing specific string from header from fasta file

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I'm looking to obtain organism name from a fasta header file, where I'm interested in from the description to extract when OS=(Organism Name).

FASTA HEADER 
>sp|Q8T8B9|ACMSD_CAEEL 2-amino-3-carboxymuconate-6-semialdehyde decarboxylase OS=Caenorhabditis elegans GN=acsd-1 PE=2 SV=1
MPICEFSATSKSRKIDVHAHVLPKNIPDFQEKFGYPGFVRLDHKEDGTTHMVKDGKLFRV
VEPNCFDTETRIADMNRANVNVQCLSTVPVMFSYWAKPADTEIVARFVNDDLLAECQKFP
GKEHIVLGTDYPFPLGEL
EVGRVVEEYKPFSAKDREDLLWKNAVKMLDIDENLLFNKDF
>sp|P34455|ACON_CAEEL Probable aconitate hydratase, mitochondrial OS=Caenorhabditis elegans GN=aco-2 PE=3 SV=2
MNSLLRLSHLAGPAHYRALHSSSSIWSKVAISKFEPKSYLPYEKLSQTVKIVKDRLKRPL
TLSEKILYGHLDQPKTQDIERGVSYLRLRPDRVAMQDATAQMAMLQFISSGLPKTAVPST
IHCDHLIEAQKGGAQDLARAKDLNKEVFNFLATAGSKYGVGFWKPGSGIIHQIILENYAF
Code for Obtaining FastaHeader 
from Bio import SeqIO
import re
import pandas as pd


input_file = "ANIMAL.fasta" 

fasta_sequences = SeqIO.parse(open(input_file),'fasta')
for fasta in fasta_sequences:
    fasta_id, sequence = fasta.id, str(fasta.seq)
    print(fasta.description)

Current Output:

>sp|Q8T8B9|ACMSD_CAEEL 2-amino-3-carboxymuconate-6-semialdehyde decarboxylase OS=Caenorhabditis elegans GN=acsd-1 PE=2 SV=1

>sp|P34455|ACON_CAEEL Probable aconitate hydratase, mitochondrial OS=Caenorhabditis elegans GN=aco-2 PE=3 SV=2

Desired Output:

Caenorhabditis elegans
Caenorhabditis elegans
biopython fasta bioinformatics python
1 Answers

You can search for your information using a regex:

import re
example = "sp|P34455|ACON_CAEEL Probable aconitate hydratase, mitochondrial OS=Caenorhabditis elegans GN=aco-2 PE=3 SV=2"

start = re.search("OS", example).start()
result = example[start+3:].split("GN")[0].strip()
print(result)
>> Caenorhabditis elegans

This Code looks for the text after "OS=" until "GN" and removes the whitespaces at the end

user_131983750
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