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282 results on '"LaPara, Timothy M."'

26. Stratification of activity and bacterial community structure in biofilms grown on membranes transferring oxygen

Author

Cole, Alina C., Semmens, Michael J., and Lapara, Timothy M.

Subjects
Microbial mats -- Growth, Microbial growth -- Research, Oxygen -- Physiological transport, Oxygen -- Analysis, Company growth, Biological sciences
Abstract

The unique stratification of membrane-aerated biofilms (MABs) in relation to bacterial community structure and function was characterized. Result indicates that the bacterial community structure and activity in MABs is stratified as a function of biofilm depth and there exists a possibility of the coexistence between ammonia-oxidizing bacteria (AOB) and denitrifying bacteria in an MAB.

Published
2004

33. Phylogenetic analysis of bacterial communities in mesophilic and thermophilic bioreactors treating pharmaceutical wastewater

Author

LaPara, Timothy M., Nakatsu, Cindy H., Pantea, Lisa, and Alleman, James E.

Subjects
Phylogeny -- Analysis, Bacteria, Thermophilic -- Genetic aspects, Bioreactors -- Testing, Water reuse -- Research, Biological sciences
Abstract

Research describes bacterial community structures of a industrial wastewater treatment facility, consisting of four thermophilically operating and three low temperature operating reactors, by denaturing gel electrophoresis combined with PCR and cloning techniques. Similar populations of bacterial species were observed under both conditions but relative species distribution was different.

Published
2000

34. THERMOPHILIC AEROBIC WASTEWATER TREATMENT IN CONTINUOUS-FLOW BIOREACTORS

Author

LaPara, Timothy M., Konopka, Allan, Nakatsu, Cindy H., and Alleman, James E.

Subjects
Water treatment plants -- Production management, Bioreactors -- Fluid dynamics, Bacteria, Thermophilic -- Usage, Engineering and manufacturing industries, Environmental issues
Abstract

Thermophilic aerobic biological wastewater treatment was investigated at 55 degrees C in continuous-flow bioreactors using a synthetic wastewater containing gelatin and (alpha)-lactose as principal organic constituents. By operating multiple continuous-flow bioreactors at different hydraulic residence times (HRTs), the maintenance constant (k(sub d)) was calculated to be 0.046 day-(super -1), a value approximately 10-fold lower than that previously reported for thermophilic processes but similar to that for mesophilic treatment. Investigation into the bacterial community structure by denaturing gradient gel electrophoresis of polymerase chain reaction-amplified 16S ribosomal RNA genes revealed that the dominant phylotypes in the bioreactors changed as a function of HRT. Cell reactivity, measured as the specific content of protein and RNA, declined as HRT increased. Catabolic enzyme activities specific to the principal organics in the synthetic wastewater, however, increased at higher HRTs. In conclusion, the performance of thermophilic aerobic biological wastewater treatment processes was similar to that of conventional mesophilic processes with respect to maintenance requirements (i.e., cell yields) as well as bacterial community shifts, cell reactivity, and cell activity.

Published
2000

50. Flushing of Stagnant Premise Water Systems after the COVID-19 Shutdown Can Reduce Infection Risk by Legionellaand Mycobacteriumspp.

Author

Hozalski, Raymond M., LaPara, Timothy M., Zhao, Xiaotian, Kim, Taegyu, Waak, Michael B., Burch, Tucker, and McCarty, Michael

Abstract

There is concern about potential exposure to opportunistic pathogens when reopening buildings closed due to the COVID-19 pandemic. In this study, water samples were collected before, during, and after flushing showers in five unoccupied (i.e., for ∼2 months) university buildings with quantification of opportunists via a cultivation-based assay (Legionella pneumophilaonly) and quantitative PCR. L. pneumophilawere not detected by either method; Legionellaspp., nontuberculous mycobacteria (NTM), and Mycobacterium aviumcomplex (MAC), however, were widespread. Using quantitative microbial risk assessment (QMRA), the estimated risks of illness from exposure to L. pneumophilaand MAC via showering were generally low (i.e., less than a 10–7daily risk threshold), with the exception of systemic infection risk from MAC exposure in some buildings. Flushing rapidly restored the total chlorine (as chloramine) residual and decreased bacterial gene targets to building inlet concentrations within 30 min. During the postflush stagnation period, the residual chlorine dissipated within a few days and bacteria rebounded, approaching preflush concentrations after 6–7 days. These results suggest that flushing can quickly improve water quality in unoccupied buildings, but the improvement may only last a few days.

Published
2020
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