Factor Analysis of the Impact of the Environment on Microbial Communities in the Tvärminne Area, Southern Coast of Finland

Biochemical fingerprinting of water coliform bacteria, a new method for measuring phenotypic diversity and for comparing different bacterial populations

A simple, automated microplate system for biochemical characterization of water isolates can be used to obtain fingerprints of the bacterial flora from various water samples. Mathematical models for calculating the diversities and similarities between bacterial populations are described for such fingerprints. The diversity may give information on whether an indigenous or allochthonous flora is present, and the similarities between bacterial populations, as calculated by using a population similarity coefficient (Sp), may indicate contaminations between different water samples. The system was demonstrated on coliform bacterial populations from various water samples, with or without suspected intercontamination. For unrelated water samples, the Sps were close to 0, whereas repeated samples of the same source showed Sps of 0.64 to 0.74. The Sp values from several water samples were also clustered to form a dendrogram, thus indicating the relative similarities between the bacterial populations to confirm suspected common sources of pollution.

Direct differential counting compared with testing of isolates as means of assessing hydrolytic capacities of natural microbial populations

The abundance of microorganisms with characteristic, physiological activities in aquatic sediment communities can be estimated either by direct differential counting on selective media or by making isolations followed by testing of the isolates. The two methods have been compared with regard to microorganisms performing hydrolyses of different compounds. The first method was used to examine the effect of a model ecocontaminant on the hydrolytic activities of the sediment population.

Ecology and taxonomy of chitinoclasticCytophaga and related chitin-degrading bacteria isolated from an estuary

A total of 103 strains of estuarine, Chitinoclastic bacteria isolated from water, and sediment samples collected from the upper Chesapeake Bay, including 17 freshwater and 11 seawater isolates, were subjected to numerical taxonomy analysis. The isolates included 44 yellow-orange pigmented strains classified asCytophaga-like bacteria (CLB) of theCytophagaceae. Salt requirement of the strains ranged from tolerance to ≤1% NaCl to an absolute requirement for NaCl, with 1% NaCl satisfying this requirement. The largest phenon consisted of facultatively anaerobic, oligo-nitrophilic, and flexirubin pigment-producing freshwater and estuarine isolates, and included reference strains of bothCytophaga johnsonae Stanier andCytophaga aquatilis Strohl and Tait. Other phena, containing a smaller number of strains, comprised marine and estuarine isolates which did not produce flexirubin pigments, and required organic nitrogen for growth and for production of chitinolytic enzymes. Salt-requiring, flexirubin pigment-producing, chitin-degrading strains were, on occasion, isolated from estuarine samples and represented phena found in estuaries. Most of theCytophaga isolates, as well as chitin-degrading species not of the genusCytophaga that were isolated from Chesapeake Bay, clustered in phena representing previously described species of aerobic, zymogenic, chitinoclastic bacteria. When the frequency of occurrence of features related to environmental parameters, viz., pH, salinity, temperature range of growth, and growth on media lacking organic nitrogen, was calculated, ecological groupings of strains in the 2 major phena of CLB could be distinguished among the estuarine, chitin-degrading bacteria.

Correlations Between Predominant Heterotrophic Bacteria and Physicochemical Water Quality Parameters in Two Canadian Rivers

The heterotrophic bacterial populations in two contrasting rivers have been examined over a period of 1 year. The populations were analyzed (i) as total heterotrophic counts, (ii) as species numbers, using numerical taxonomy, (iii) by diversity indices, and (iv) by factor analysis. Isolates were obtained by plating directly from water samples and by chemostat enrichment. Four factors emerged which profiled the bacterial community and were common to both rivers. They were, in order of decreasing importance, fermentative metabolism, inorganic nitrogen metabolism, fluorescence-oxidative metabolism, and lack of starch hydrolysis. Several factors produced significant correlations with a range of physicochemical parameters, which were also measured. The correlations suggested an intricate algal-bacterial interaction. The oxidative metabolism factor correlated with rainfall in one river, suggesting that the oxidative bacteria may be washed in from the surrounding land. In the other river, the oxidative-fermentative factor correlated negatively with sunshine. Factor analysis was the most effective method for revealing correlations between bacterial characteristics and the environmental parameters; however, the use of a variety of methods provided more insight into the ecological aspects.

Effects of Environmental Factors on Microbial Populations in Brackish Waters off the Southern Coast of Finland

The roles played by environmental factors in seasonal changes in microbial populations were investigated in the Tvärminne area, off the southern coast of Finland. Surface-layer samples were collected at 1- or 2-week intervals in 1976-78, and 14 microbiological and 10 environmental parameters were determined. Stepwise multiple regression analysis was used to explain seasonal variation in the microbiological parameters. Separate analyses were made of the data from the open-water and ice-cover periods. In analyses of data from both periods, the environmental factors included accounted for a significant proportion of the variation in the parameters for community respiration (90%) and bacterial spores (80%), and a smaller proportion (60 to 65%) of the variation in total counts of bacteria and plate counts of psychrophiles and yeasts. Lower values (40 to 55%) were obtained for the variation in the other microbiological parameters. The environmental factors with maximal contributions were organic matter, water temperature, chlorophyll a , and salinity, but rainfall and winds also explained part of the variation in some microbiological parameters. In the winter analysis the results differed from those obtained for the other seasons, the variation being governed by parameters indicating freshwater outflows, namely, humic matter, salinity, water temperature (positive regression coefficient), and rainfall (negative regression coefficient).