Pretty limited with regards to any sort of 'large corporations', but you will find excess of sherry warehouses etc. Jerez is not a very wealthy area of spain and most people farm or are involved in sherry in some way. You might find it quite hard to get a job if you don't speak spanish. All I can recommend is go out there for couple of days and have a look. If you are interested I can give you the best hotel to stay at in town (with discount).
Rgds.