A Participatory Cloud Infrastructure (PCI) is a collaborative framework designed to host services for a virtual community thanks to residential devices contributed by its members. In this work, we deploy on these devices a photo-sharing application based on microservices. The placement of services on devices significantly influences the overall performance of the application. To address this concern, we present a heuristic able to find a placement that approximates the ideal application response-time in constant time. Our proposed approach has undergone validation within a real infrastructure, revealing the necessity for dynamic adjustments of service placements. Consequently, we introduce a comprehensive adaptation process for placement and an associated specialized strategy.