Incidence of Prosthecate Bacteria in a Polluted Stream

Water samples were collected aseptically several times throughout the year at nine stations on the Red Cedar River, a stream flowing through farmland and receiving effluent from several municipalities in central Michigan. Total prosthecate bacteria were enumerated by both direct and viable counting techniques. By direct techniques, these bacteria accounted for 0.62 to 1.1% of the total microflora during the study. The predominant type of appendaged bacteria was the caulobacters (Caulobacter, Asticcacaulis, and the fusiform caulobacter), which accounted for 64 to 93% of the total prosthecate forms. The others of importance were prosthecomicrobia (< 1 to 24%), including Prosthecomicrobium and Prosthecochloris; hyphomicrobia (< 1 to 15%), including Hyphomicrobium and Rhodomicrobium; and Ancalomicrobium (< 1 to 6%). The viable counts of heterotrophs also indicated that the caulobacters were the most numerous prosthecate bacteria in the stream. They ranged from fewer than 1 per ml to a maximum of almost 4,000 per ml. During the coldest period, when the total viable counts decreased to about 10(4) per ml compared to their summer high of over 10(7) per ml, the caulobacters actually increased in numbers. In December (temperature 0 to 1 C), they comprised from 0.09 to 1.0% of the viable microbial count, and in March (6.0 to 8.0 C) they accounted for 0.14 to 2.8%. The other heterotrophic prosthecate bacteria were generally found at numbers less than 1 per ml, with the exception of the December study when Hyphomicrobium was present in numbers as high as 2,400 per ml. There was no consistent correlation between the frequency of prosthecate bacteria and total coliforms in the stream during the investigation.     

Survival of Escherichia coli in lake bottom sediment.

The survival of Escherichia coli in bottom sediment (Lake Onalaska, navigation pool no. 7, Mississippi River) was studied by using in situ dialysis culture of sterile (autoclaved) and unsterile sediment samples. Bags made from dialysis tubing were filled with either course sand sediment (28.8% fine) or organic, silty clay sediment (77.2% fine) and placed at the sediment-water interface. Bags representing sterile controls, unsterile uninoculated controls, autoclaved inoculated sediment, and unsterile inoculated sediment were studied during a 5-day period for each sediment type. Daily most-probable-number determinations indicated that E. coli populations in unsterile inoculated sediment fluctuated between 5.3 X 10(2) and 2.2 X 10(3) bacteria per g of silty clay and between 3.0 X 10(3) and 1.4 X 10(4) bacteria per g of sand. Autoclaved silty clay sediment inoculated with 1.0 X 10(6) bacteria per g increased to 2.2 X 10(8) bacteria per g in 3 days. During the same period, autoclaved sand sediment inoculated with 1.2 X 10(5) cells per g increased to 5.4 X 10(7) bacteria per g. By day 5, populations in both cultures had decreased by 1 log. The ability of E. coli to survive for several days in aquatic sediment in situ suggests that fecal coliforms in water may not always indicate recent fecal contamination of that water but rather resuspension of viable sediment-bound bacteria.     

Antibody-coated bacteria in the urine of preschool and school-aged girls with asymptomatic bacteriuria.

Urine samples from 3564 girls aged 2 to 13 years were screened for evidence of infection. Cultures were positive (bacteria count, more than 10(5)/ml) in 61 (1.7%) by the dipslide method and in 55 (1.5%) by standard culture techniques. In 13 (23.6%) of the 55, antibody-coated bacteria (ACB) were detected in the urine. The clinical, bacteriologic, radiologic and urinalysis findings in children with ACB were no different from those in children in whom the bacteria were not coated. Direct examination of uncentrifuged urine under high power revealed one or more bacteria per two high-power fields in 96% of infected urine samples and in only 7% of noninfected samples. Five or more leukocytes per high-power field in centrifuged urine were detected in 36.7% of infected urine samples but not in noninfected samples. The ACB test did not differentiate between asymptomatic bacteriuria with parenchymal scarring or vesicoureteral reflux or both and asymptomatic bacteriuria without these abnormalities.     

Oral bacteria resistant to mercury and to antibiotics are present in children with no previous exposure to amalgam restorative materials

Dental plaque from 76 children without amalgam restorations was screened for bacteria resistant to mercuric chloride. Seventy-one per cent of the children harboured mercury-resistant oral bacteria and the median percentage of the total oral microflora resistant to mercuric chloride was 0.007% (range 0-5.3%). Eighty-seven mercury-resistant bacteria were isolated and 86% of these were streptococci with Streptococcus mitis predominating. Sixty per cent of the mercury-resistant isolates were also resistant to at least one of the four antibiotics tested (penicillin, ampicillin, erythromycin and tetracycline) with resistance to tetracycline (40% of isolates) most frequently encountered.     

Three-year investigation of the natural airborne bacterial flora at four localities in sweden.

The concentration of airborne bacteria was recorded during a period of 3 years at four localities: (i) in an agricultural district with an average of 99 (range, 2 to 3,400) bacteria per m3; (ii) in a coastal area with an average of 63 (range, 0 to 560) bacteria per m3; (iii) in a city park with an average of 763 (range, 100 to 2,500) bacteria per m3; and (iv) in a city street with an average of 850 (range, 100 to 4,000) bacteria per m3. At all four localities the bacterial concentrations varied within broad limits, but an annual periodicity with high average counts found during summer and autumn could be seen. The influence of certain meteorological factors on the number of airborne bacteria is also reported. Rain or high relative humidity caused a decrease in the bacterial counts, while high temperature or high wind velocities increased the counts. The particle size distribution for the four localities showed that about 50% of the particles carrying bacteria were larger than 8 micrometer.     

The aerobic and anaerobic microbiology of pustular acne lesions

Specimens from 32 pustular acne lesions that were inoculated on media supportive for the growth of aerobic and anaerobic bacteria showed bacterial growth. Only aerobic or facultative bacteria were recovered in 15 (47%) specimens, only anaerobic bacteria in 11 (34%) specimens, and mixed aerobic and anaerobic bacteria in 6 (18%) specimens. A total of 57 isolates, 31 anaerobes (1.0 per specimen) and 26 aerobes (0.8 per specimen) were recovered. The predominant isolates were Staphylococcus sp. (19 isolates), Peptostreptococcus sp. (15), and Propionibacterium sp. (10). Twelve (37.5%) of the comedones yielded only one organism. This retrospective study highlighted the polymicrobial nature of over two-thirds of culture positive pustular acne lesions and suggests the potential for pathogenic role of aerobic and anaerobic organisms other than P. acnes and Staphylococcus sp. in acne vulgaris.     

Quantitative selection of denitrifying bacteria in continuous cultures and requirement for organic carbon. II. Maltose

A mixed population of bacteria from industrial nitrogen wastewaters was incubated in continuous culture in medium containing 1000-1300 mg nitrate nitrogen per litre and maltose as a source of organic carbon. Maximal efficiency of denitrification was 8.6 mg N/1/h. The participation of denitrifying bacteria in the culture varied from 0% to about 80%, depending on the ratio of maltose concentration (CM) to nitrogen concentration (CN) in the medium. The optimal CM/CN ratio ensuring the greatest selection of denitrifying bacteria was 5.0, which calculated per organic carbon (CC/CN) gave the value of 2.1. The amount of maltose needed to denitrify a defined amount of nitrogens was negatively correlated (rxy = -0.95) with the frequency of denitrifying bacteria (XD) in the culture and was: CM = (4.20-0.026XD)CN. The denitrifying bacteria isolated from the studied continuous culture were dominated by Alcaligenes faecalis and Pseudomonas mendocina.     

Seasonal variation in the abundance and heterotrophic activity of suspended bacteria in two lowland rivers

SUMMARY. 1. Water samples were collected over two years from the Yorkshire Ouse and Yorkshire Derwent and the following were measured: (i) concentration of directly-counted bacteria (free-living and particle-bound), (ii) concentration of colony-forming units, (iii) bacterial heterotrophic activity (turnover rate for glucose assimilation), (iv) specific activity (turnover rate per bacterium), (v) a range of environmental variables.
2. The abundance and activity of suspended bacteria showed similar seasonal periodicities in both rivers.
3. Free-living bacteria were usually more numerous than particle-bound bacteria; low concentration of free-living bacteria and maxima of particle-bound bacteria usually occurred in winter.
4. Concentration of colony-forming units varied irregularly, but lowest levels were found in summer.
5. Turnover rate and turnover rate per bacterium showed distinct summer maxima.
6. Multiple-regression analysis was used to relate bacterial variables to subsets (chosen by factor analysis) of environmental variables; up to 89% of variation in bacterial variables was related to the combined effects of variation by variables in the chosen subsets.     

Routine fluorescence in situ hybridization in soil

The use of fluorescence in situ hybridization (FISH) to identify and enumerate soil bacteria has long been hampered by the autofluorescence of soil particles masking the bacterial signals and because the need of counting hundreds of bacteria in order to achieve statistically reliable data is time consuming. Recently, it was demonstrated that Nycodenz facilitates FISH in soil by concentrating bacteria on membrane filters and avoiding autofluorescent soil particles. We present a routine protocol for FISH in soil including the use of Nycodenz. The protocol allows fast and easy enumeration of hundreds of bacteria. We propose the use of silicon grease coated slides to treat in parallel seven samples per hybridization. Further, we developed a semi-automated approach for the enumeration of bacteria by implementing macros concatenating all steps of the image analyzes in the Image J software. Using Nycodenz, software-assisted bacterial counts statistically matched eye-counts of the same images and it was possible to count 880 DAPI stained bacteria per ten images. Fifty-five percent of these bacteria were co-labelled with the FISH probe specific for the Domain Bacteria, in accordance with recent FISH studies of bacterial populations in bulk soil. With a soil slurry protocol used for comparison, soil particles impaired automatic counts of the bacteria and FISH analysis, and only 88 DAPI stained bacteria per ten images could be counted by eye. With the Nycodenz protocol, 5 mM Na(2)EDTA used as an extractant increased the number of bacteria observed by 49%. In contrast, Tween 20 (1% or 5%) had no significant effect and increased the variability between the samples. Overall, the proposed procedure allows to process a high number of samples and to achieve a time efficient FISH characterization of soil bacterial communities.     

Effect of sodium chloride on transport of bacteria in a saturated aquifer material.

Determinations were made of the influence of NaCl concentration, cell density, and flow velocity on the transport of Pseudomonas sp. strain KL2 through columns of aquifer sand under saturated conditions. A pulse-type boundary condition was used. The experiments were conducted by using 0.3-m-long Plexiglas columns with an internal diameter of 0.05 m. When a 1-h pulse of a 0.01 M NaCl solution containing 10(8) cells per ml was added at a flow rate of 10(-4) m s-1, the bacterial density in the effluent never exceeded 2.2% of the density of cells added, and only 1.5% of the bacteria passed through the aquifer material. In contrast, when the bacteria were applied in distilled water, the relative cell density in the effluent approached 100%, and 60% of the bacteria were transported through the aquifer solids. Under these conditions, the breakthrough of Pseudomonas sp. strain KL2 was slower than chloride. When the flow rate was 2.0 x 10(-4) m s-1, the cell density in the effluent reached 7.3% of that added in 0.01 M NaCl solution, but only 3.9% of the bacteria were transported through the aquifer particles. On the other hand, the density in the effluent approached 100% of that added in deionized water, and 77% of the added bacteria were recovered. When the density of added cells was 10(9) cells per ml at a flow rate of 10(-4) m s-1, the densities in the effluent reached 70 and 100% of those added in salt solution and deionized water, respectively, and 44 and 57% of the bacteria were transported through the aquifer solids.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of sodium chloride on transport of bacteria in a saturated aquifer material.

Determinations were made of the influence of NaCl concentration, cell density, and flow velocity on the transport of Pseudomonas sp. strain KL2 through columns of aquifer sand under saturated conditions. A pulse-type boundary condition was used. The experiments were conducted by using 0.3-m-long Plexiglas columns with an internal diameter of 0.05 m. When a 1-h pulse of a 0.01 M NaCl solution containing 10(8) cells per ml was added at a flow rate of 10(-4) m s-1, the bacterial density in the effluent never exceeded 2.2% of the density of cells added, and only 1.5% of the bacteria passed through the aquifer material. In contrast, when the bacteria were applied in distilled water, the relative cell density in the effluent approached 100%, and 60% of the bacteria were transported through the aquifer solids. Under these conditions, the breakthrough of Pseudomonas sp. strain KL2 was slower than chloride. When the flow rate was 2.0 x 10(-4) m s-1, the cell density in the effluent reached 7.3% of that added in 0.01 M NaCl solution, but only 3.9% of the bacteria were transported through the aquifer particles. On the other hand, the density in the effluent approached 100% of that added in deionized water, and 77% of the added bacteria were recovered. When the density of added cells was 10(9) cells per ml at a flow rate of 10(-4) m s-1, the densities in the effluent reached 70 and 100% of those added in salt solution and deionized water, respectively, and 44 and 57% of the bacteria were transported through the aquifer solids.(ABSTRACT TRUNCATED AT 250 WORDS)     

Lactobacilli in Ensiled High-Moisture Corn

Aerobic mesophilic bacteria, molds, yeasts, and Lactobacillus species were enumerated at various intervals of the ensiling process of high-moisture corn (HMC). A total of 466 isolates of Lactobacillus were identified to determine the species of Lactobacillus associated with ensiled HMC and remoistened corn. The numbers of aerobic bacteria in the ensiled HMC increased to 10(8) per gram within 1 week and remained at this level throughout the storage period. The numbers of aerobic bacteria in the remoistened corn increased to 10(9) per gram and remained at this level during the 60-day storage period, after which they increased rapidly. Yeasts were the predominant microflora of the ensiled HMC. Mold numbers were low in the silos, but were very high in the remoistened corn, especially toward the end of the 60-day storage period. The species of Lactobacillus most frequently isolated from the ensiled HMC were L. plantarum, 52% of the isolates; L. brevis, 19% of the isolates; L. brevis (atypical), 15%; L. fermenti, 11%; and L. buchneri, 3%. The lactic acid bacteria, therefore, are the predominant bacterial flora of ensiled HMC, as they are of other types of plant forages that undergo similar fermentations.     

Identity and Behavior of Xylem-Residing Bacteria in Rough Lemon Roots of Florida Citrus Trees

An aseptic vacuum extraction technique was used to obtain xylem fluid from the roots of rough lemon (Citrus jambhiri Lush.) rootstock of Florida citrus trees. Bacteria were consistently isolated from vascular fluid of both healthy and young tree decline-affected trees. Thirteen genera of bacteria were found, the most frequently occurring genera being Pseudomonas (40%), Enterobacter (18%), Bacillus, Corynebacterium, and other gram-positive bacteria (16%), and Serratia (6%). Xylem bacterial counts fluctuated seasonally. Bacterial populations ranged from 0.1 to 22 per mm³ of root tissue (about 10² to 2 × 10⁴ bacteria per g of xylem) when bacterial counts were made on vascular fluid, but these numbers were 10- to 1,000-fold greater when aseptically homogenized xylem tissue was examined similarly. Some of the resident bacteria (4%) are potentially phytopathogenic. It is proposed that xylem bacteria have an important role in the physiology of citrus.     

Possible food chain relationships between bacterioplankton,protozoans, and cladocerans in a reservoir

Ingestion of fluorescent particles by natural protozoan assemblage was studied in the Řimov Reservoir (Southern Bohemia) from April to October, 1987. Attached and free-living bacterial abundance, proportion of active bacteria, density of suspended particles and biomass of cladocerans were also monitored. Heterotrophic nanoflagellates (HNF; 5–12.8 10²ml⁻¹) were the dominant bacterial micrograzers during the spring period and consumed 3 to 9% of the total bacteria per day. After the spring phytoplankton bloom maximum densities of suspended particles and attached bacteria (up to 28% of the total counts) were found. Development of cladocerans in May sharply decreased the proportion of attached bacteria and kept them below 5% of the total counts. All the studied components of plankton except Cladocera decreased during the clearwater phase. The most significant drop was observed in the numbers of protozoans, and they were negligible for bacterial elimination. Bacterial losses during that time apparently were due to cladoceran grazing. During the summer period, ciliates (15–142 ml⁻¹) were mostly dominant micrograzers, and protozoan community grazing increased up to 21% of bacterial standing stock per day. The proportion of active bacteria was strongly correlated with protozoan grazing (r=0.83).     

Occurrence of tributyltin-tolerant bacteria in tributyltin- or cadmium-containing seawater.

Tributyltin chloride (TBTCl)-tolerant bacteria accounted for 90% of the flora in natural seawater to which TBTCl was added. These tolerant bacteria were insensitive to 250 nmol of TBTCl per disc, and all were Vibrio species. Total counts of viable bacteria did not decrease upon storage of the TBTCl-treated seawater, indicating that enrichment of tolerant strains took place. Addition of CdSO4 to seawater resulted in the occurrence of TBTCl-tolerant bacteria as well as Cd-tolerant bacteria, suggesting some correlation of Cd tolerance and TBTCl tolerance.     

Occurrence of tributyltin-tolerant bacteria in tributyltin- or cadmium-containing seawater.

Tributyltin chloride (TBTCl)-tolerant bacteria accounted for 90% of the flora in natural seawater to which TBTCl was added. These tolerant bacteria were insensitive to 250 nmol of TBTCl per disc, and all were Vibrio species. Total counts of viable bacteria did not decrease upon storage of the TBTCl-treated seawater, indicating that enrichment of tolerant strains took place. Addition of CdSO4 to seawater resulted in the occurrence of TBTCl-tolerant bacteria as well as Cd-tolerant bacteria, suggesting some correlation of Cd tolerance and TBTCl tolerance.     

Distribution of Polyunsaturated Fatty Acids in Bacteria Present in Intestines of Deep-Sea Fish and Shallow-Sea Poikilothermic Animals

The lipid and fatty acid compositions in nine obligate and facultative barophilic bacteria isolated from the intestinal contents of seven deep-sea fish were determined. Phospholipid compositions were simple, with phosphatidylethanolamine and phosphatidylglycerol predominating in all strains. Docosahexaenoic acid (DHA; 22:6n-3), which has not been reported in procaryotes except for deep-sea bacteria, was found to be present in eight strains at a level of 8.1 to 21.5% of total fatty acids. In the other strain, eicosapentaenoic acid (EPA; 20:5n-3) was present at a level of 31.5% of total fatty acids. Other fatty acids observed in all strains were typical of marine gram-negative bacteria. Subcultures from pouches prepared from intestinal contents of five deep-sea fish by the most-probable-number (MPN) method were analyzed for fatty acids, and all subcultures contained DHA and/or EPA. Accordingly, viable cell counts of bacteria containing DHA and EPA were estimated at a maximum of 1.3 x 10(sup8) and 2.4 x 10(sup8) cells per ml, respectively, and accounted for 14 and 30%, respectively, of the total cell counts in the intestinal contents of the deep-sea fish. In the case of 10 shallow-sea poikilothermic animals having bacterial populations of 1.1 x 10(sup6) to 1.9 x 10(sup9) CFU per ml in intestinal contents, no DHA was found in the 112 isolates examined, while production of EPA was found in 40 isolates from cold- and temperate-sea samples. These results suggest that DHA and EPA are involved in some adaptations of bacteria to low temperature and high pressure.     

Chitinolytic bacteria and chitin mineralization in the marine waters and sediments along the Antartic Peninsula

Abstract Chitinolytic bacteria were enumerated and isolated from marine waters and sediments along the highly productive Antarctic Peninsula. Chitinolytic bacteria were found in low concentrations (approximately 1 cell per ml) in the water column and at much higher levels in marine surface sediments (10⁴–10⁵ per g). The predominant chitinolytic bacteria isolated from the water column were identified as psychrophilic Vibrio spp. Rates of chitin mineralization were measured by collection of ¹⁴CO₂ respired from ¹⁴C-labeled chitin synthesized from chitosan and [1-¹⁴C]acetic anhydride. Chitin mineralization rates were extremely low in the marine waters analyzed (0.00085–0.0019% of the added label respired in 48 h) and appreciably higher in the marine sediments (0.0039–0.01% per 48 h), suggesting that the sediments are much more important in chitin degradation. Such low mineralization rates suggest that chitin may be accumulating in Antarctic marine sediments, though animals may also play an important role in chitin degradation.     

Polythene and plastic-degrading microbes in an Indian mangrove soil

Biodegradation of polythene bags and plastic cups was analyzed after 2, 4, 6, and 9 months of incubation in the mangrove soil. The biodegradation of polythene bags was significantly higher (up to 4.21% in 9 months) than that of plastic cups (up to 0.25% in 9 months). Microbial counts in the degrading materials were recorded up to 79.67 x 10(4) per gram for total heterotrophic bacteria, and up to 55.33 x 10(2) per gram for fungi. The microbial species found associated with the degrading materials were identified as five Gram positive and two Gram negative bacteria, and eight fungal species of Aspergillus. The species that were predominant were Streptococcus, Staphylococcus, Micrococcus (Gram +ve), Moraxella, and Pseudomonas (Gram -ve) and two species of fungi (Aspergillus glaucus and A. niger). Efficacy of the microbial species in degradation of plastics and polythene was analyzed in shaker cultures. Among the bacteria, Pseudomonas species degraded 20.54% of polythene and 8.16% of plastics in one-month period. Among the fungal species, Aspergillus glaucus degraded 28.80% of polythene and 7.26% of plastics in one-month period. This work reveals that the mangrove soil is a good source of microbes capable of degrading polythene and plastics.     

Microbial degradation of oxalate in the gastrointestinal tracts of rats.

Rates of oxalate degradation by mixed bacterial populations in cecal contents from wild rats ranged from 2.5 to 20.6 mumol/g (dry weight) per h. The oxalate-degrading activity in cecal contents from three strains of laboratory rats (Long-Evans, Wistar, and Sprague-Dawley) from four commercial breeders was generally lower, ranging from 1.8 to 3.5 mumol/g (dry weight) of cecal contents per h. This activity did not increase when diets were supplemented with oxalate. When Sprague-Dawley rats from a fifth commercial breeder were fed an oxalate diet, rates of oxalate degradation in cecal contents increased from 2.0 to 23.1 mumol/g (dry weight) per h. Obligately anaerobic, oxalate-degrading bacteria, similar to ruminal strains of Oxalobacter formigenes, were isolated from the latter group of laboratory rats and from wild rats. Viable counts of these bacteria were as high as 10(8)/g (dry weight) of cecal contents, which was less than 0.1% of the total viable population. This report presents the first evidence for the presence of anaerobic oxalate-degrading bacteria in the cecal contents of rats and represents the first direct measurement of the concentration of these bacteria in the large bowel of monogastric animals. We propose that methods used for the maintenance of most commercial rat colonies often preclude the intestinal colonization of laboratory rats with anaerobic oxalate-degrading bacteria.