I have to say that it does look like Jerens, taking all the other examples of handwriting on the image into account.
I notice that the certificate you have was ordered from the GRO. Can you tell, does all the handwriting, including all the signatures (of those who could actually sign their name), look the same? If so, I would be inclined to try and track down the original register to see if the writing is any clearer.
Am I right in thinking that the transcription you've already seen was on the Lancashire Online Parish Clerk's website? The transcriptions for Tyldesley seem to have been taken from LDS microfilm, which I would have thought had been taken from the original registers anyway, so the transcriber could have had a much better certainty of the name, but I think it might still be worth your while. Looking at the Manchester Central Library website, the Tyldesley marriage register after 1837 is missing:http://www.manchester.gov.uk/info/448/archives_and_local_stu...
This makes me think that the marriage registers may still be kept by the church, so you could try contacting them to see whether they would look at the register for you, or whether you could have a look at it yourself if you're in the area. The two contacts I've found are the vicar:http://www.achurchnearyou.com/tyldesley-st-george/
and perhaps a churchwarden(?):http://www.tyldesley.towntalk.co.uk/local/d/3135/parish-chur...