Norval A. Sinclair

Microbial quality and persistence of enteric pathogens in graywater from various household sources

Abstract This study was designed to evaluate the microbial quality and safety of graywater for reuse purposes. The microbial and chemical composition of graywater from shower/bath, wash cycle and rinse cycle of a clothes washing machine was determined. Graywater composed from all sources within a house was also monitored each week over a 2–3-month time period. Samples were taken from a diverse group of families with children (18 months–9 years of age) and without children. Standard plate count bacteria (SPC) ranged from 105 to 1010 colony forming units (cfu) per 100 ml for shower and bath water, and an average of 104 to 106 cfu per 100 ml for total coliforms. Families with small children produced wash cycle graywater containing 106 cfu per 100 ml of fecal coliforms. During investigations on storage of graywater, it was found that total bacterial SPC and coliform baceria increased one order of magnitude. Salmonella atyphimurium and Shigella dysenteriae seeded into graywater were found to persist for at least several days. Poliovirus type 1 added to graywater decreased 99 and 90% at 25 and 17°C, respectively, after 6 d of storage in graywater. These data imply that there may be some risk associated with reuse of graywater when these pathogenic bacteria or viruses are being excreted by an individual producing the graywater.

The effect of indigenous bacteria on virus survival in ground water

Abstract Over one‐half of the waterborne disease outbreaks in the United States are due to the consumption of contaminated ground water. Although viruses are a major cause of illness in these outbreaks, very little is known about the factors which influence how long viruses can remain infective in ground water. Experiments were conducted using several ground water samples obtained from drinking water wells to determine the effects of the naturally‐occurring bacteria on the survival of coliphage MS‐2 and poliovirus type 1 inoculated into the samples. The numbers of bacteria and viruses were monitored over a 30‐day period. Parallel experiments were conducted using water which had been filtered to remove the bacteria. The increase in bacterial numbers in the first 24 hours of incubation was significantly correlated with the decay rate of coliphage MS‐2. However, consistent trends were found in the ability of the viruses to persist in the presence or absence of bacteria.

Physiology and kinetics of manganese‐reducing bacillus polymyxa strain D1 isolated from manganiferous silver ore

Abstract Manganese‐reducing bacteria were isolated from a manganiferous silver ore mining site using enrichment procedures. The most rapid Mn(IV) reducer was identified as Bacillus polymyxa and was designated as strain D1. Isolate D1 has no growth‐factor requirements and is mesophilic and neutrophilic. D1 respires glucose aerobically, under which conditions cyanide is bactericidal. Nonfermentable substrates such as lactate, acetate, citrate, and succinate cannot serve as sole carbon sources. D1 ferments glucose anaerobically, producing acetic acid, ethanol, and butanediol as major metabolic end products. Both anaerobic conditions and direct physical contact with pyrolusite (MnO2) particles were necessary for manganese reduction. Strain D1 is unique in that manganese serves as an ancillary electron acceptor during anaerobic fermentation. Kinetic experiments showed that D1 reduced manganese three to five times as rapidly as the widely studied Mn(IV)/Fe(III)‐reducing microorganisms Shewanella putrefaciens MR...

Microorganism removal from wastewater by rapid mixed media filtration

Abstract Reuse of domestic sewage effluents in Arizona requires that certain microbiological standards be met. The purpose of this project was to determine the effectiveness of rapid mixed media filtration in the removal of enteric viruses, fecal coliforms and roundworm eggs from sewage destined for reuse as irrigation water. Two surrogate viruses, the simian rotavirus SA-11, used in place of human rotavirus which is pathogenic to man, and f2 coliphage, known to adsorb poorly to surfaces, were used to evaluate filter performance. No significant removal of coliphages occurred by the filters. Addition of ferric chloride and anionic polymer did not enhance virus removal. When small amounts of alum and polymer were added, removal of colliphage increased to 37–40%. Average removal of rotavirus ranged from 21 to 27% after addition of alum and polymer. Mixed media filtration effectively reduced coliform numbers. The removal of Ascaris ova by filtration was essentially complete.

Isolation and physiology of a manganese-reducing Bacillus polymyxa from an Oligocene silver-bearing ore and sediment with reference to Precambrian biogeochemistry

Abstract Samples from an Oligocene silver-bearing manganese ore mining site in Saguochi country, Colorado were screened for bacteria which solubilize manganese in the refractory ore thus making the silver more amenable to standard extraction techniques. Over 300 bacterial isolates were tested. Manganese reduction was detected by growing the organisms in a mineral salts medium supplemented with the insoluble MnO2 (pyrolusite). Reduction of the black MnO2 resulted in the formation of colorless solubilized Mn2+. One of the most efficient manganese reducers was a Bacillus polymyxa strain D1. This bacterium was isolated from the ore heap and from a zone 5 cm below the sediment surface of the inlet which drained ore heap leachate into a holding pond. Isolate D1 has a unique mode of manganese reduction as shown by the following combination of characteristics: (1) anaerobiosis is absolutely necessary; (2) direct surface contact with the mineral particle is required; (3) facultative fermentation occurs concomitantly with manganese reduction; and (4) Mn4+ does not substitute for O2 at the end of the respiratory electron transport chain. Although the ore deposit is approximately 35-30 Ma old, D1 probably have first appeared at the site contemporaneous with mining activities as evidenced by its resistance to exogenous zinc used in the silver extractive process. If organisms such as D1 were present > 600 Ma ago they could have played a role in the Precambrian manganese cycle as they do in the Holocene. Encrustations of MnO2 have been found in Precambrian sediments which are thought to be biogenic in origin. Solubilized reduced Mn2+ must also have been present to serve as a substrate. Anaerobic conditions alone are insufficient for the reduction of manganese dioxide, therefore, it is likely that manganese reduction was due, in part, to microbial activity. Solubilization of manganese occurs via microbial dissimilatory reduction as seen with isolate D1. Precipitation results from oxidation of manganese coupled to ATP synthesis as described by Ehrlich (1976, 1983).

Plasmid diversity within a 2,4-dichlorophenoxyacetic acid-degrading Variovorax paradoxus population isolated from a contaminated soil

Abstract Thirty‐two 2,4‐dichlorophenoxyacetic acid (2,4‐D)‐degrading (Tfd∗) isolates of Variovorax paradoxus were obtained from a sample of contaminated soil by enrichment culture and were divided into six groups based on the size and number of plasraids they contained. Isolates within each of the six groups had identical and unique plasmid profiles consisting of multiple plasmids of diverse size. Curing of plasmids resulted in loss of ability to degrade 2,4‐D. EcoR1 restriction patterns of plasmids contained by Tfd∗ and Tfd‐ clones suggested that the plasmids did not derive from a common origin, since patterns revealed unique differences as well as similarities in restriction fragment size. In addition, the data suggest that in situ gene transfer and recombination events occurred frequently within this population.

Bioprocessing of refractory oxide ores by bioreduction: Extraction of silver, molybdenum, and copper

Abstract Although much research has been conducted in the area of biooxidation of sulfide ores, few investigations in the bioreduction of oxide ores have been published. We report high recoveries of silver, molybdenum, and copper from refractory oxide ores through bioreduction. Metal-reducing Bacilli solubilize manganese and iron. Crystals of pyrolusite, goethite, and hematite are bacterially dissolved and entrapped target metal ions are released. Zinc and copper are solubilized by metabolic end products such as organic acids. Bioreductive leaching of oxide ores was more successful than chemical leaching. A 0.1% cyanide bottle roll on an Arizona manganiferous silver ore resulted in 13.7% silver extraction. Bioreductive leaching extracted 86% of the silver into the growth medium. Also, 99.8% of the manganese, >2;99% of the copper, and 91% of the zinc were solubilized. A cyanide bottle roll of the bioleached solids extracted an additional 8.5% of the silver for a total recovery of 94.5%. A 5% sulfuric acid bottle roll of a Nevada iron oxide molybdenum ore recovered 1.8% of the moly. Bioreduction solubilized 93% of the molybdenum into the growth medium. A follow-up acid bottle roll recovered no additional moly. Bioreductive leaching can be used to recover target metals from refractory oxide ores without the use of cyanide or sulfuric acid.

Application of phage typing to the identification of sources of groundwater contamination

Abstract Phage typing of Escherichia coli populations was used as a “fingerprinting” tool to identify the source(s) of fecal coliform contamination of a drinking water well, PW- 12 . Group discriminate analysis was used to evaluate the data and determine the relative distance of population centroids from the centroid of the PW- 12 population. The phage typing patterns were compared to serological results and correlations noted. Phage typing patterns were shown to be stable following 32-days incubation of E. coli isolates in garden soil, tap water and neutralized tertiary effluent, with and without the presence of autochthonous flora.

A selective medium for the isolation of opportunistic flavobacteria from potable water

Abstract A selective medium was developed for the primary isolation of opportunistic flavobacteria from potable water. A minimal‐salts maltose yeast extract agar medium (MSMY) supplemented with either kanamycin (MSMY‐K) or tobramycin (MSMY‐T) was effective in suppressing the background microflora from most sources while allowing for the growth of Flavobacterium meningosepticum and Flavobacterium IIb. Opportunistic flavobacteria were isolated from 30% of potable well and 10% of potable distribution water samples tested using MSMY‐K in a membrane filtration technique.