Table 1. Summary of the 16S ribosomal RNA gene sequence based metagenomic analysis results of the datasets used in this study.

Country	Number of samples used in this study*	Average read length	Number of reads used in this study^	Average number of reads per sample	Number of OTUs	Number of genera	No of unknown OTUs	Reads mapping to known genera (%)	Reads mapping to unknown genera (%)	ENA Accession Numbers	References
Burkina Faso	9	254	173012	19223.56	1257	57	26	91.93039	8.06961	ERP000133	[20]
Egypt	8	253	383613	47951.63	3368	121	81	64.55591	35.44409	PRJNA328966	[58]
China	57	402	245706	4310.632	3551	94	26	70.46069	29.53931	PRJDB1664	[16]
Taiwan	53	402	269446	5083.887	3509	89	24	71.48267	28.51733	PRJDB1664	[16]
Thailand	50	400	326087	6521.74	3922	108	34	71.77727	28.22273	PRJDB1664	[16]
Indonesia	55	401	354766	6450.291	3961	117	39	75.82541	24.17459	PRJDB1664	[16]
Japan	79	403	457678	5793.392	3572	85	29	67.03656	32.96344	PRJDB1664	[16]
India	14	175	15072369	1076598	5660	152	49	76.8114	23.1886	SRP041693, SRP055407, DRA002238	[59]
Malaysia	6	186	4196544	699424	4287	105	34	78.07753	21.92247	SRP079939	[60]
Italy	13	262	205151	15780.85	2347	73	21	57.50687	42.49313	ERP000133	[20]
Spain	40	448	1479424	36985.6	3693	101	37	66.12199	33.87802	PRJNA350839	[61]
Sweden	9	98	2531749	281305.4	5085	95	34	61.0206	38.9794	ERP020401	[62]
Colombia	30	217	513077	17102.57	4030	102	41	53.73231	46.26769	ERP003466	[39]
U.S.A	62	512	2122144	34228.13	4207	107	38	68.82446	31.17554	PRJNA297510	[63]
Argentina	10	483	88490	8849	1470	58	25	69.30452	30.69548	SRP062999	[44]
	495		13346887		53919