Why dance around the templating provided by EasyBuild like this?
There are two better alternatives for this:

• use the namelower template, i.e.:

source_urls = [('http://sourceforge.net/projects/%(namelower)s/files/%(namelower)s/%(version)s', 'download')]

• use the SOURCEFORGE_SOURCE constant:

source_urls = [SOURCEFORGE_SOURCE]

Please use the latter, which is equivalent to http://download.sourceforge.net/%(namelower)s (see eb --avail-easyconfig-templates), in all Boost easyconfigs. I have a branch ready that does just that, let me know if you'll clean this up or I should open the PR (which will cause conflicts with what you currently have).

sorry for the delay, I fixed it as per 2nd suggestion; I'm fun of the motto:
less chars to type => less human in the process => more robust

Please use SOURCEFORGE_SOURCE here too, and in all other Boost easyconfigs.

OK, done... please review

Use a different construction here, to avoid unintentionally breaking the match with versionsuffix and dep:

name = 'Mothur'
version = '1.30.2'

biodeps = 'biodeps'
biodeps_ver = '1.6'
versionsuffix = '-%s-%s' % (biodeps, biodeps_ver)

dependencies = [
    (biodeps, biodeps_ver),
    ('gzip', '1.5'),
]

Likewise for the other easyconfigs that use biodeps, of course.

Homepage doesn't make sense... Better use (none), like we do for e.g. goolf.
Or maybe better, refer to the relevant HPCBIOS page?

OK, good catch, thanks for spotting... fixed, please re-re-re-re-review!