(Petaluma360) - Beer is downsizing. Following the arc of small-scale artisan salumi, cheese, bread, olive oil and garagiste winemakers, now micro-batched, regionally-sourced, hand-crafted beer is the hottest thing in brewing. And the North Bay has a growing stake in the trend.Somewhere between home-brewing and micro-brewing is nano-brewing. To illustrate the scale: Home brewers typically make about 5 gallons per batch. Nano-brewers, between one and three barrels at a time, topping out at a few hundred barrels annually. Micro-brewers like Petaluma's Lagunitas Brewing Company make 600,000 barrels annually; a large “craft” brewer like Samuel Adams, 6 million barrels per year. Anheuser-Bush produces upwards of 100 million barrels per year.