how to extract text between two delimiters when string is present

Question

I have a large data file which looks like:

//
ID   1.1.1.258
DE   6-hydroxyhexanoate dehydrogenase.
CA   6-hydroxyhexanoate + NAD(+) = 6-oxohexanoate + NADH.
CC   -!- Involved in the cyclohexanol degradation pathway in Acinetobacter
CC       NCIB 9871.
//
ID   1.1.1.259
DE   3-hydroxypimeloyl-CoA dehydrogenase.
CA   3-hydroxypimeloyl-CoA + NAD(+) = 3-oxopimeloyl-CoA + NADH.
CC   -!- Involved in the anaerobic pathway of benzoate degradation in
CC       bacteria.
//
ID   1.1.1.260
DE   Sulcatone reductase.
CA   Sulcatol + NAD(+) = sulcatone + NADH.
CC   -!- Studies on the effects of growth-stage and nutrient supply on the
CC       stereochemistry of sulcatone reduction in Clostridia pasteurianum,
CC       C.tyrobutyricum and Lactobacillus brevis suggest that there may be at
CC       least two sulcatone reductases with different stereospecificities.
//

I want to extract sections of this file that contain the work anaerobic . I specifically want the ID line.

Is there a means to search the file between ID and // to find anaerobicand print the output to a new file? If the whole section is printed that is fine as I figure I can grep it out after.

Expected out should be either

ID   1.1.1.259

or

ID   1.1.1.259
DE   3-hydroxypimeloyl-CoA dehydrogenase.
CA   3-hydroxypimeloyl-CoA + NAD(+) = 3-oxopimeloyl-CoA + NADH.
CC   -!- Involved in the anaerobic pathway of benzoate degradation in
CC       bacteria.
//

Answer 1

it's simple with awk

awk '/anaerobic/' RS='//\n' ORS='\n//' ./file.txt