Browsing by Author "Peter Van Berkum"
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Item Enumeration and Localization of N2-Fixing Bacteria Associated with Roots of Spartina alterniflora Loisel(1983-06) Robertson Mcclung, C.; Peter Van Berkum; Robert E. Davis; Charles SlogerNumbers and possible locations of N2-fixing bacteria were investigated in roots of Spanuia alterniflora Loisel. which support nitrogenase activity in the undisturbed native habitat. N2-fixing bacteria were recovered in cultures both from 5. altcrniflora roots and from the surrounding: sediment, and they formed a greater proportion of the bacteria recovered from root homogenates than from salt-marsh sediment. N -.-fixing bacteria were recovered in high numbers from the rhizoplane of S. alterniflora after roots were treated with 1 or 5% chloramine-T for 1 h or with 1% NaOCl for 1 or 2 h. Immersing 5. alterniftora roots in 5% NaOCl for 1 h was more effective in distinguishing bacteria inside the roots since this treatment nearly eliminated N:-fixing bacteria recoverable from the rhizoplane, although high numbers of N;-fixing bacteria were recovered from homogenates of roots treated with 59£ NaOCl for 1 h. However, this treatment was less effective with roots of Zea mays L. (Funks G4646) and Sorghum bicolor (L.) Moench (CK.-60 A), indicating that techniques to surface sterilize roots should be evaluated for different plants. Bacteria were observed by light and electron microscopy mter-and intracellularly in the cortex and in the aerenchyma of S. alterniflora roots. This study clearly shows that bacteria, including N2 fixers, colonize the interior of roots of 5. alterniflora growing in a Chesapeake Bay, Maryland, salt marsh.Item Nitrate reduction and nitrogenase activity in Spirillum lipoferum(1977) Carlos A. Neyraz; Peter Van Berkum