Circadian changes in the hindgut bacterial composition of the American cockroaches, Periplanata americana (Dictyoptera, Blattodea)

The gut of American cockroaches, Periplanata americana hosts numerous symbionts that help in digestion and synthesis of many substances. The hindgut of cockroaches is unique in that it harbors higher number of microbes than other parts of the insect’s gut. Unlike gut enzymes activities, little is known about the daily pattern of the gut microbiota. Newly emerged adult American cockroaches collected from student hostel were used for this study. The hindgut microbial composition was examined at four periods of the day (6am, 12pm, 6pm and 12am) using Pour Plate Methods. The results showed that highest colony forming units (cfu) of the hindgut were recorded at 6:00pm (19.28 × 106 cfu/ml) followed by 6:00am (13.85 × 106 cfu/ml) while 12:00pm (3.02 × 106 cfu/ml) had the least. Also, a total of five (5) different bacteria (Klebsiella sp., Staphylococcus aureus, Pseudomonas aeruginosa, Citrobacter sp. and Escherichia coli) were isolated from the hindgut of the cockroaches. The most predominant of these bacterial isolates from the hindgut were Klebsiella sp. and Staphylococcus aureus while the least isolated organism was Citrobacter sp. Hence, there was circadian variation in the microbial composition of the hindgut of Periplaneta americana.