I find this question, but it uses command line, and I do not want to call a Python script in command line using subprocess and parse HTML files to get the font information.
This approach does not use PDFMiner but does the trick.
First, convert the PDF document into docx. Using python-docx you can then retrieve font information. Here's an example of getting all the bold text
from docx import *
document = Document('/path/to/file.docx')
for para in document.paragraphs:
for run in para.runs:
if run.bold:
print run.text
If you really want to use PDFMiner you can try this. Passing '-t' would convert the PDF into HTML with all the font information.