Silicon Valley nonprofits and arts groups, which got about $2 million a year from San Jose-based Knight Ridder, are worried about how they’ll meet their funding needs with the demise of the newspaper chain. Dean Singleton, chief executive of Media News which is acquiring KR’s Northern California papers including the Mercury News, said he leaves philanthropic decisions up to the publishers of his individual newspapers, but he acknowledged that the loss of KR’s corporate headquarters will be a blow to San Jose. “We’ll be generous because we believe in that, but it won’t match a corporate headquarters,” Singleton was quoted by Mercury News as saying.