Public Transportation options from Des Moines International Airport:  Note that cabs serve any location in central Iowa, while buses serve  throughout the Metro area. 
The Executive Express shuttle service has a booth in the baggage claim area, providing service to Ames and other Iowa cities.

Des Moines Area Regional Transit 'DART' public Bus Route 8 serves the Airport. (tel. 515-283-8100 - for route map open: & schedule open http://www.ridedart.com/bus-schedulesroute-map.cfm).
Heart of Iowa Regional Transit Agency 'HIRTA' (tel. 877-686-0029  or visit:  www.hirtapublictransit.com) is an interstate transit bus line linking Central Iowa and the surrounding counties around Polk (where the Airport & the City of Des Moines are)
To/from Iowa State University (ISU)  at 2501 N.Loop Drive, Ames, IA 50321:  (if driving go north to I-80; east on 163 & north on I35; exit at SR 30 with a short drive west to Ames. The 40.6 mile distance takes about 48 mins (without traffic). For transportation options to ISU, open its website.

Google Plus One