TABLE 1.

Soil metagenomic libraries constructed with or without formamide treatment

Library name	Library type	Nycodenz isolationa	Formamide treatment	No. of clones	Approx % insert	Avg insert size (kb)
AK 5	BAC	Yes	No	2,200	70	33
AK 7	BAC	Yes	No	2,300	60	47
AK 8	BAC	Yes	No	2,700	70	9
AK 9	BAC	Yes	No	2,400	25	20
AK 13	BAC	No	No	8,400	10	29
AK 17	BAC	No	No	1,000	20	29
AK 15	BAC	No	Yes	32,100	60	20
AK 19	Fosmid	No	Yes	3,300	98	31
AK 20	BAC	No	Yes	48,100	80	8
AK 21	Fosmid	No	Yes	333,700	100	30
AK 22	Fosmid	No	Yes	50,500	100	30
AK 23	Fosmid	No	Yes	8,200	100	30

^aIn some cases, microbial cells were isolated over a Nycodenz layer as previously described (22).