Amazon Prime members in the Twin Cities can now enjoy one of the latest perks of the online juggernaut's industry-shaking purchase last year of Whole Foods -- delivery within two hours of groceries, including fresh and organic produce as well as meat and seafood, from the retailer's shelves.

The delivery is handled through Amazon's same-day delivery arm Prime Now, which uses independent contractors driving their own cars to bring items to customers' doorsteps.

Amazon first began rolling out delivery from Whole Foods stores in a handful of markets in February, one of the first major integrations since its acquisition. In addition to Minneapolis, Amazon is expanding the service this week to four other cities -- Chicago, Houston, Indianapolis, and San Antonio. It's now up and running in about 20 cities and Amazon says it will bring it to more this year.

Same-day delivery from Whole Foods has already been available in the Twin Cities and many other parts of the country through Instacart.

This week, Amazon also announced it will also make its discounts for Prime members at Whole Foods, an initiative it had started adding in some markets, available to customers nationwide starting Wednesday. Prime members can get 25 percent off bulk items such as nuts and granola, 10 percent off sale items and other discounts on select items such as baby back pork ribs and sockeye salmon at Whole Foods.

To get the discounts, Prime members have to download the Whole Foods app, sign in with their Amazon account, and scan their Prime code at checkout. Or they can use a mobile number to get the savings.

"Customer feedback has been overwhelmingly positive - in fact, Prime members have adopted this benefit at one of the fastest rates we've seen," Cem Sibay, vice president of Amazon Prime said in a statement.

Prime members will also be able to get the special pricing when they order groceries from Whole Foods through Prime Now. For the delivery, customers can place orders through the Prime Now app or from www.primenow.com.

Two-hour deliveries are free on orders over $35, but tips are suggested for drivers. One-hour delivery costs $7.99.

Prime Now delivery and the discounts at Whole Foods are only available to Prime members. Amazon recently hiked the annual fee for a Prime membership to $119 from $99.

Following its acquisition, Amazon also has lowered the prices on some products at Whole Foods and made some of Whole Foods' private label brands available on Amazon.com and via Prime now.

Meanwhile, other retailers have been sharpening their grocery and delivery game in response to Amazon's big moves in the space. Minneapolis-based Target, for example, has been rolling out same-day delivery of groceries, household essentials, and other items through its subsidiary, Shipt, which it acquired last year.

By the end of this month, Target said it will have same-day delivery via Shipt up and running in more than 135 markets, including in recently added cities such as Chicago and other parts of the Midwest. It brought the service to the Twin Cities in March and plans to have it in operation from most of its stores by this holiday. Annual memberships to Shipt cost $99.

Walmart is also rolling out grocery delivery to 100 metro areas this year with the help of third-party delivery partners such as Deliv and DoorDash. The service launched in the Twin Cities about a month ago.