SINGAPORE, Aug 5 (Reuters) - London-headquartered private equity asset manager Apis Partners LLP said on Thursday it has invested $32 million in DOKU, an Indonesian digital payments firm owned by tech and media firm Emtek Group, in a market seeing strong growth and consolidation. Founded in 2007, DOKU earns the majority of its revenue by processing online payments for large and small businesses in Southeast Asia"s largest economy, one of the fastest growing e-commerce markets worth an estimated $40 billion. "We have invested in payments gateways in Africa and in other parts of Southeast Asia and India because we feel that the future is digital payments and these spur online transactions," Matteo Stefanel, co-founder and managing partner at Apis, told Reuters.