environmental samplesuncultured Prochlorococcus sp.uncultured Prochlorococcus sp.uncultured Prochlorococcus sp.uncultured Prochlorococcus sp.uncultured Prochlorococcus sp.uncultured Prochlorococcus sp.uncultured Prochlorococcus sp.uncultured Prochlorococcus sp.uncultured Prochlorococcus sp.uncultured Prochlorococcus sp.uncultured Prochlorococcus sp.