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The Mycoplasma Genitalium Mg_454 Gene Product Resists Killing By Organic Hydroperoxides, Sankaralingam Saikolappan, Smitha Sasindran, Hongwei Yu, Joel Basema, Subramanian Dhandayuthapani
The Mycoplasma Genitalium Mg_454 Gene Product Resists Killing By Organic Hydroperoxides, Sankaralingam Saikolappan, Smitha Sasindran, Hongwei Yu, Joel Basema, Subramanian Dhandayuthapani
Hongwei Yu
Mycoplasma genitalium is the smallest self-replicating organism and a successful human pathogen associated with a range of genitourinary maladies. As a consequence of its restricted genome size, genes that are highly conserved in other bacteria are absent in M. genitalium. Significantly, genes that encode antioxidants like superoxide dismutase and catalase-peroxidase are lacking. Nevertheless, comparative genomics has revealed that MG_454 of M. genitalium encodes a protein with putative function as an organic hydroperoxide reductase (Ohr). In this study, we found that an M. genitalium transposon mutant that lacks expression of MG_454 was sensitive to killing by t-butyl hydroperoxide and cumene hydroperoxide. …
Enumeration Of Sandy Sediment Bacteria: Search For Optimal Protocol, Slava Epstein, Jeffrey Rossel
Enumeration Of Sandy Sediment Bacteria: Search For Optimal Protocol, Slava Epstein, Jeffrey Rossel
Slava Epstein
We examined and compared a variety of existing protocols for enumeration of bacteria from marine sandy sediments. The focus was on how to dislodge bacteria from sediment particles; a commercial blender, an ultrasonic cleaner, and an ultrasonic cell disrupter were tested. The ultrasonic cell disrupter was found to be the most efficient device for bacterial dislodgment. With a 5 mm microtip vibrating at 109 μm amplitude and 20 kHz, the optimal sonication time of small (≤ 0.5 cm³) samples was 180 s. Having identified the optimal dislodgment treatment, we went through other steps of sediment bacteria enumeration (use of surfactants, …
The Acid Stress Response Of The Cyanobacterium Synechocystis Sp. Strain Pcc 6308, Jean Huang, Nancy Kolodny, Jennifer Redfearn, Mary Allen
The Acid Stress Response Of The Cyanobacterium Synechocystis Sp. Strain Pcc 6308, Jean Huang, Nancy Kolodny, Jennifer Redfearn, Mary Allen
Jean J. Huang
The cyanobacterium Synechocystis sp. strain PCC 6308 has been shown to exhibit predictable physiological responses to acid stress. Originally isolated from a Wisconsin lake, this cyanobacterium grows optimally under alkaline conditions in the laboratory. After acid stress at a pH of between 4.4 and 7.7, cells return to exponential growth following a lag phase. The organism's response to this tolerable acid stress involves cell concentration-dependent neutralization of the external medium to pH 6 or above within 5 min, maintenance of a transmembrane pH gradient, and maintenance of photosystem II efficiency. Lethal acid stress, at a pH below 4.4, results in …