S-189 gives Fermentis a second dry lager option alongside W-34/70, and the two are distinguished by attenuation running the opposite direction from what the product codes might suggest — S-189 tops out at 78-83%, a few points lower than W-34/70's 80-84% at both ends. That gap is modest but consistent: S-189 leaves more residual extract behind at packaging, which reads as a rounder, maltier finish rather than the leaner, crisper profile W-34/70 is best known for. Brewers reaching for S-189 over its sibling are usually after that fuller body for a maltier lager style, not a drier one.
Like any lager strain, S-189 needs genuine cold fermentation temperatures within its 48-59°F range to perform at its best, along with an adequate pitch rate and the patience for extended cold conditioning afterward. Skip either step and the same off-character and sulfur-related issues that dog the whole classic lager-strain family will show up here too — S-189 isn't more forgiving of shortcuts than its more famous sibling, just built toward a different finished-beer profile once the process is done right.
Lager and pilsner styles wanting a rounder, more traditional malt-forward finish are S-189's natural fit — Vienna lager, Märzen and other beers where a touch of residual body is welcome rather than trimmed away. Medium-high flocculation gives it solid clearing behaviour once fermentation and the subsequent lagering period have both had adequate time to do their work. As a dry lager strain it offers the same starter-free convenience relative to a liquid lager strain that W-34/70 does, at the same cost: no substitute for the specific liquid-yeast formats some experienced lager brewers still prefer for their most serious, competition-focused batches.