how to find if there are bacterium specific adapters in the reads?

There should be no organism specific adapters. Adapters generally come from the kit used to make the libraries.

That said programs like fastp (LINK) and bbmerge.sh from BBMap suite (see --> Identify adapter sequences for trimming from Illumina paired end fastq files ) can help automatically identify adapters, when you don't know the exact library kit used.

You can download UniVec_Core fasta file, then extract primers/adapters (say sequences < 100bp?) and use seqkit locate to search some subset of reads (10-100k) from the intact FASTQ files. This way you may figure out if there are any adapters in your sequences, what these are and the location. At times ppl either on purpose or by mistake do non-obvious things, where read_length > insert_length and you will have a detectable the adapter sequence in large proportion or even all the reads (small RNA i.e.)