Non-saline Environments Research Articles

An antibiotic, heavy metal resistant and halotolerant Bacillus cereus SIU1 and its thermoalkaline protease

BackgroundMany workers have reported halotolerant bacteria from saline conditions capable of protease production. However, antibiotic resistance and heavy metal tolerance pattern of such organisms is not documented very well. Similarly, only a few researchers have reported the pattern of pH change of fermentation medium during the course of protease production. In this study, we have isolated a halotolerant Bacillus cereus SIU1 strain from a non-saline environment and studied its antibiotic and heavy metal resistance pattern. The isolate produces a thermoalkaline protease and changes the medium pH during the course of fermentation. Thermostability of protease was also studied for 30 min.ResultsSeventy bacterial strains isolated from the soils of Eastern Uttar Pradesh, India were screened for protease production. All of them exhibited protease activity. However, 40% bacterial isolates were found good protease producers as observed by caseinolytic zones on milk agar plates. Among them, culture S-4 was adjudged as the best protease producer, and was identified as Bacillus cereus by morphological, biochemical and 16 S rDNA sequence analyses. The isolate was resistant to heavy metals (As2+, Pb2+, Cs1+) and antibiotics (penicillin, lincomycin, cloxacillin, pefloxacin). Its growth behavior and protease production was studied at 45°C and pH 9.0. The protease units of 88 ml-1 were noted in unoptimized modified glucose yeast extract (GYE) medium during early stationary phase at 20 h incubation period. The enzyme was stable in the temperature range of 35°-55°C.ConclusionsAn antibiotic and heavy metal resistant, halotolerant Bacillus cereus isolate is capable of producing thermoalkaline protease, which is active and stable at pH 9.0 and 35°-55°C. This isolate may be useful in several industrial applications owing to its halotolerance and antibiotic and heavy metal resistance characteristics.

Involvement of polyamines, abscisic acid and anti-oxidative enzymes in adaptation of Blue Panicgrass ( Panicum antidotale Retz.) to saline environments

A hydroponic experiment was conducted to assess the possible involvement of polyamines (PAs), abscisic acid (ABA) and anti-oxidative enzymes such as superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) in adaptation of six populations of Panicum antidotale Retz. to selection pressure (soil salinity) of a wide range of habitats. Plants of six populations were collected from six different habitats with ECe ranging from 3.39 to 19.23 dS m −1 and pH from 7.65 to 5.86. Young tillers from 6-month-old plants were transplanted in plastic containers each containing 10 l of half strength Hoagland's nutrient solution alone or with 150 mol m −3 NaCl. After 42 days growth, contents of polyamines (Put, Spd and Spm) and ABA, and the activities of anti-oxidative enzymes (SOD, POD and CAT) of all populations generally increased under salt stress. The populations collected from highly saline habitats showed a greater accumulation of polyamines and ABA and the activities of anti-oxidative enzymes as compared to those from mild or non-saline habitats. Moreover, Spm/Spd and Put/(Spd + Spm) ratios generally increased under salt stress. However, the populations from highly saline environments had significantly higher Spm/Spd and Put/(Spd + Spm) ratios as compared to those from mild or non-saline environments. Similarly, the populations adapted to high salinity accumulated less Na + and Cl − in culm and leaves, and showed less decrease in leaf K + and Ca 2+ under salinity stress. Higher activities of anti-oxidative enzymes and accumulation of polyamines and ABA, and increased Spm/Spd and Put/(Spm + Spd) ratios were found to be highly correlated with the degree of adaptability of Panicum to saline environment.

Influence of thermally activated paper sludge on the behaviour of blended cements subjected to saline and non-saline environments

One of the problems to affect Portland cement matrices is low resistance to aggressive agents, due principally to the presence of a high content of portlandite in the hydrated cements. Pozzolanic materials have played an important role in the improving the durability of cement-based materials for decades. This work studies the behaviour of cement mortar matrices blended with 10% calcined paper sludge (source for metakaolinite) and exposed to different environmental conditions (saline and non-saline environments) after 6 and 12 months of exposure. Two cements were studied: an ordinary Portland cement (CEM 1, 42.5R), acting as reference cement, and a blended cement formulated by mixing 90% (by mass) of CEM 1, 42.5R with 10% (by mass) of paper sludge calcined at 700 degrees C for 2 h. The specimens were exposed 1 year to saline and non-saline environments. All the mineralogy samples were studied through X-ray diffraction and scanning electron microscopy (SEM) equipped with an energy dispersive X-ray analyser. The in-depth study on ionic mobility was performed on samples subjected to natural exposure (coast and tableland) for 6 and 12 months. Portland cement was composed of quartz, calcite, calcium hydroxide and tobermorite gels. The pozzolanic cement (10% calcined paper sludge) is of the same composition but a high calcite concentration and barium carbonate. SEM analysis from coastline show deposits of variable composition. The deposits are identified on the surface of different mineral components. The minerals from tableland are much fractured, i.e. calcite and feldspars. Inside the fractures, the deposits and the ions are located and trapped superficially. SEM analysis of control cement Portland and 10% calcined paper sludge shows deposits on quartz and calcite with a very high concentration of Pb, Zn, Cl and barium sulphate. A very porous aspect is due to the presence of the different aggregate types. This porous configuration permits retention of the ion environment. The pozzolanic cement in environments subject to the saline mist favours the retention and transport of ions observed. Something similar also happens with the increase in exposure to outdoor weather. Non-saline samples show temperature changes (ice or thaw cycles). Barium retention is kept on the surface in fracture lines by the gelification processes. In general, it may be inferred that an increase in exposure time increases the diffusion of ions towards test piece interiors. The chemical composition profiles show that the ions present different penetration speeds. The results indicate the better vulnerability of pozzolanic cements from calcined paper sludge in saline and non-saline environments. The cements with a 10% addition of calcined paper sludge favour retention and transport of ion has been observed. Today, projects are centred on a new recycling line for industrial waste of this kind, with special attention on its incorporation in cement manufacture as a pozzolanic material, setting the most appropriate activation conditions of the mineralogical compound in this waste (kaolinite and metakaolinite) and taking them as a starting point for this project. The use of pozzolanic cement with 10% addition of calcined paper sludge is a system which favours ionic retention.

Surface and internal deterioration of concrete due to saline and non-saline freeze–thaw loads

Concrete deterioration due to frost action in non-saline and saline environments was studied statistically. The most significant variables affecting the freeze–thaw durability of concrete were calculated statistically and contours of estimated response surface were produced. Water–cement ratio and air content of the concretes were the most dominant variables affecting the internal and surface damage caused by the freezing and thawing loads. In the non-saline environment, water curing improved the R 2 values of the developed deterioration models in the surface scaling part of the tests. In the internal damage tests, the curing measures did not improve the statistical relevancy of the estimated response surfaces. In the saline freeze–thaw tests, high-strength concretes were studied. When water–binder ratio was below 0.42 internal deterioration was the governing freeze–thaw damage mechanism which needed larger air content compared to surface scaling.

Endospores of halophilic bacteria of the family Bacillaceae isolated from non-saline Japanese soil may be transported by Kosa event (Asian dust storm)

BackgroundGenerally, extremophiles have been deemed to survive in the extreme environments to which they had adapted to grow. Recently many extremophiles have been isolated from places where they are not expected to grow. Alkaliphilic microorganisms have been isolated from acidic soil samples with pH 4.0, and thermophiles have been isolated from samples of low temperature. Numerous moderately halophilic microorganisms, defined as those that grow optimally in media containing 0.5–2.5 Molar (3–15%) NaCl, and halotolerant microorganisms that are able to grow in media without added NaCl and in the presence of high NaCl have been isolated from saline environments such as salterns, salt lakes and sea sands. It has tacitly been believed that habitats of halophiles able to grow in media containing more than 20% (3.4 M) are restricted to saline environments, and no reports have been published on the isolation of halophiles from ordinary garden soil samples.ResultsWe demonstrated that many halophilic bacteria that are able to grow in the presence of 20% NaCl are inhabiting in non-saline environments such as ordinary garden soils, yards, fields and roadways in an area surrounding Tokyo, Japan. Analyses of partial 16S rRNA gene sequences of 176 isolates suggested that they were halophiles belonging to genera of the family Bacillaceae, Bacillus (11 isolates), Filobacillus (19 isolates), Gracilibacillus (6 isolates), Halobacillus (102 isolates), Lentibacillus (1 isolate), Paraliobacillus (5 isolates) and Virgibacillus (17 isolates). Sequences of 15 isolates showed similarities less than 92%, suggesting that they may represent novel taxa within the family Bacillaceae.ConclusionThe numbers of total bacteria of inland soil samples were in a range from 1.4 × 107/g to 1.1 × 106/g. One tenth of the total bacteria was occupied by endospore-forming bacteria. Only very few of the endospore-forming bacteria, roughly 1 out of 20,000, are halophilic bacteria. Most of the halophilic bacteria were surviving as endospores in the soil samples, in a range of less than 1 to about 500/g soil. Samples collected from seashore in a city confronting Tokyo Bay gave the total numbers of bacteria and endospores roughly 1000 time smaller than those of inland soil samples. Numbers of halophilic bacteria per gram, however, were almost the same as those of inland soil samples. A possible source of the halophilic endospore originating from Asian dust storms is discussed.

Shoot Biomass Production among Accessions of Medicago truncatula Exposed to NaCl

Increased salt tolerance would improve utilization of salt‐sensitive crop plants such as alfalfa (Medicago sativa L.). In order for selection for salt tolerance to be more efficient, it is useful to know whether improved productivity under saline conditions is due to unique physiological responses to salinity or merely the carry over of increased yield that was selected for in a nonsaline environment. Medicago truncatula Gaertn., a self‐pollinated relative of alfalfa, was used to examine the response of specific genotypes across a range of salinities. This was done by evaluating the change in fresh shoot biomass production of greenhouse‐grown mature plants and seedlings of different accessions of M. truncatula in response to four levels of salinity imposed as NaCl. Those accessions with the highest fresh shoot biomass production under nonsaline irrigation also had the highest fresh shoot biomass production under all salinity levels. The high correlation between an accession's fresh shoot biomass under nonsaline and saline irrigation indicate no unique physiological adaptation to salinity in the accessions of M. truncatula evaluated.

Study of Salinity Tolerance in Rapeseed

Eight diverse Brassica napus genotypes and their 28 F1s were evaluated in nonsaline and saline environments in sand culture. Combined analysis based on two salinity levels revealed significant salinity-level effects for shoot dry weight, plant height, root length, and ions in shoot tissues, including potassium (K), sodium (Na), Ca/Na, and K/Na. Salinity had no significant effect on shoot calcium (Ca) concentration. Stress intensity (SI) estimates, its larger values indicating the more severe stress intensities, were high for all studied traits except for root length, Ca, and Na. The mean of Na in a saline environment was more than seven times the mean in a nonsaline environment, therefore SI was not calculated for this parameter. Low estimates of SI for root length and Ca indicated the effects of a saline environment for these two traits were less than for the other traits. Significant interactions of genotype and salinity levels were observed for all studied traits. The results of factor analysis based on minimum eigenvalue revealed two factors for eight studied traits in a saline environment. Factor one was detected as a nutritional trait in which Ca, K, Ca/Na, and K/Na had a high coefficients factor loading. Factor two was detected as morphological traits. The results of factor analysis indicated that selection for nutritional traits should be more efficient than selection for morphological traits and, specifically, that selection based on K and K/Na should be more efficient than Ca and Ca/Na. Significant positive correlations were found between shoot dry weight and other traits, including Ca, K, Ca/Na, and K/Na in a saline environment; therefore, these ion relations can be used as good selection criteria for improving shoot dry weight. On the basis of low estimates of the tolerance index (TOL) for shoot dry weight (its large value represents more sensitivity to stress), it was concluded that the genotypes including BL2, Ceres, Shiralee, Falcon × BL2, PF7045/91 × Ceres, and BL2 × Ceres had suitable salinity tolerance in early stages of growth.

The potential of subterranean microbes in facilitating actinide migration at the Grimsel Test Site and Waste Isolation Pilot Plant

Microorganisms may affect the long-term stability and mobility of radionuclides disposed of in deep geological formations. Of particular concern is the association of radionuclides with subterranean microbial cells and their subsequent transport as biocolloids. We characterized the total microbial populations in two groundwater samples: one from the Culebra dolomite member of the Rustler Formation at the Waste Isolation Pilot Plant (WIPP), NM, and the other from the granitic formation at the Grimsel Test Site (GTS), Switzerland. Culebra groundwater (ionic strength 2.8 M, pH 7) contained 1.51 ± 1.08 × 105cells ml-1, with a mean cell length of 0.75 ± 0.04 μm and width of 0.58 ± 0.02 μm. In contrast, low ionic-strength GTS groundwater (0.001 M, pH 10) contained 3.97 ± 0.37 × 103cells ml-1, with a mean cell length of 1.50 ± 0.14 μm and width of 0.37 ± 0.01 μm. Adding appropriate electron donors and acceptors to the groundwaters facilitated the growth of aerobic, denitrifying, fermentative, and acetogenic microorganisms. Uranium biosorption was studied in two isolates from these groundwaters, as well as several pure cultures from saline and non-saline environments. Halophilic and non-halophilic bacteria exhibited differences in the amount of U associated with the cells. Plutonium uptake by Acetobacterium sp. isolated from GTS varied from 30 - 145 pg of Pu mg-1dry weight of cells.

Effect of salt stress on antioxidant defence system in soybean root nodules

The antioxidant defence systems of soybean (Glycine max (L.) Merr) nodules responded differently to 50 and 200 mM NaCl. At 50 mM NaCl, leghaemoglobin content and nitrogenase activity remained unaltered but there was an overall increase in the antioxidant enzymes (ascorbate peroxidase, catalase, glutathione reductase and superoxide dismutase) and in reduced glutathione. After returning the salinised nodules to a non-saline environment (recovery), the enzymatic activities returned to the initial values but reduced glutathione remained high with respect to the controls measured at the end of the experiment (final controls). Severe salt treatment reduced the leghaemoglobin content and nitrogenase activity by 31% and 50%, respectively. Ascorbate peroxidase, catalase and glutathione reductase activities decreased between 30 and 100% while superoxide dismutase and reduced glutathione increased over the controls by 19% and 30% respectively. After recovery, glutathione reductase increased over the final controls and reduced glutathione remained as under 50 mM NaCl. Malondialdehyde content and total protein remained unchanged in nodules treated with the two salt concentrations. These results suggest that under mild saline stress, the elevated levels of the antioxidant enzymes and reduced glutathione protect nodules against the activated oxygen species thus avoiding lipid and protein peroxidation, and leghaemoglobin breakdown. However, severe saline treatment produced an irreversible decay in the leghaemoglobin content and nitrogenase activity despite the high reduced glutathione level and glutathione reductase activity.

Yield, nutritive value, and phenotypic variability of tall wheatgrass grown in a nonsaline environment

The phenotypic variation of 10 important botanical traits and 2 traits related to herbage quality was measured in tall wheatgrass (Thinopyrum elongatum) cv. Tyrrell. Five certified lines of Tyrrell were compared among themselves and with cvv. Largo and San Jose. Significant differences, both between cultivars and within lines of Tyrrell, were observed for several traits. The phenotypic variability measured confirms that Tyrrell is distinct from its progenitor, Largo, and has sufficient variability to make it suitable for use in a selection program. In a second experiment, from November 1990 to February 1993, the yield and nutritive value of Tyrrell, Largo, and San Jose were compared with perennial ryegrass (Lolium perenne) cv. Ellett and tall fescue (Festuca arundinacea) cv. Demeter. There were no differences (P>0.05) between cultivars for either total dry matter yield or total yield of digestible dry matter. Seasonal differences in growth and nutritive value were observed. Ellett showed superior growth in winter and early spring, while tall wheatgrass and Demeter were more summer-active. In 6 of the 11 harvests measured for nutritive value, there were no differences (P>0.05) between treatments for yield of digestible dry matter; for 2 of the remaining 5 harvests, Tyrrell yielded more digestible dry matter than Ellett. Dry matter digestibility of tall wheatgrass did not fall below 60%. The results suggest that with appropriate management, tall wheatgrass can produce nutritious forage in quantities sufficient for animal production systems, particularly as a special purpose summer pasture.

Variation in the salinity tolerance of strawberry clover (Trifolium fragiferum L.)

Saline soils negatively affect plant growth, so there is a need to develop salt tolerant plant materials for rangeland uses. Five strawberry clover (Trifolium fragiferum L.) cultivars were compared to 95 plant introductions for tolerance to salinity during germination and greenhouse seedling growth. Mean tolerance of the cultivars to NaCl during germination did not differ significantly (p>0.05) from that of the introductions. Individual plant introduction accessions were superior to each of the cultivars in tolerance to NaCl during germination. Mean shoot dry weight, shoot height, and number of shoot branches of the cultivars were greater (p<0.05) than those of the plant introductions in both the control and saline irrigation treatments. Mean cultivar plant tolerance to salinity, as indicated by saline/control treatment ratios for shoot dry weight, shoot height, and number of branches, was not superior to that of the plant introductions. Germination tolerance to salinity was not correlated with plant growth in either saline or non-saline irrigation treatments. Ample genetic diversity is present within strawberry clover to permit development of cultivars with superior tolerance to salinity during seed germination. It will be more difficult to develop cultivars with superior plant growth in both saline and non-saline environments.

Field performance of anther-culture-derived lines from F1 crosses of Indica rices under saline and nonsaline conditions

Field experiments were conducted to evaluate and compare the yield and agronomic characteristics of anther-culture-derived (AC) lines in rice and the parents under saline and nonsaline soil conditions. The yield stability of two entries was also evaluated by comparing their performance under two distinct nonsaline soil environments. The test entries were planted in randomized complete block design with four replications at each test location. Data were collected on grain yield, yield components, and agronomic characteristics. This study demonstrates that through anther culture, it is possible to produce homozygous diploid lines in a short time. The possibility of regenerating recombinants with desirable characteristics such as good plant type and salinity tolerance, higher yield, and increased resistance to pests and diseases from both the parents is high.

Lucerne (Medicago sativa L.) selected for vigor in a nonsaline environment maintained growth under salt stress

Lucerne populations HP32 and M69-33 (Medicago sativa L.), which were developed from Hairy Peruvian (HP) and Moapa 69 (M69) by selection for increased growth and N assimilation in nonsaline conditions, also produced more forage at 20% bloom than the original cultivars when moderate salt stress was applied after germination. During the first 45 days of seedling development, the improved populations produced as much total dry matter in the presence of 150 mM NaCl as the original cultivars did in the absence of NaCl. When plants were grown to 20% bloom with 200 mM NaCl, HP32 produced 70% more forage than HP (P=0.01), while M69-33 yielded 26% more forage than M69 (P=0.05). Because all tests were conducted in the absence of combined N, growth of the improved populations was accompanied by increased N2 fixation. Superior growth of HP32 under saline conditions was associated with greater exclusion of Na (P=0.05) and Cl (P=0.08) from the leaves. These results show that selecting for increased growth and N assimilation without salt stress in two populations of lucerne provided potential agronomic benefits in both saline and nonsaline environments.

Response of barley genotypes to non-saline and saline environments

A 2-year study (1976–7) was conducted at the Safford Agricultural Center, Safford, Arizona, U.S.A. to investigate the response of barley (Hordeum vulgare L.) genotypes to both non-saline and saline environments. The soil type was a Grabe clay loam. One area had received only river irrigation water for the previous 10 years and throughout the experiment (non-saline environment); another area had been irrigated with only well water for the previous 10 years and throughout the experiment (saline environment). Analysis of the two sources of irrigation water showed that total soluble salts (TDS) and the sodium adsorption ratio (SAR) were much higher in well water than in river water. Consequently, the electrical conductivity of the saturation extract, total salt content, and exchangeable sodium percentage were all much higher in soil irrigated with well water (saline environment) than in soil irrigated with river water (non-saline environment). Fifteen barley genotypes were grown in each year. The following data were recorded for each genotype each year: (1) plant height, (2) lodging, (3) number of heads per hill, (4) number of seeds per head, (5) seed weight, (6) grain yield, (7) straw yield, (8) grain-to-straw ratio, (9) days from planting to flowering, and (10) days from flowering to maturity. Most of the barley genotypes germinated more uniformly, grew better, and produced more forage and grain in the non-saline environment than they did in the saline environment. It required a longer period for barley to reach maturity in the saline environment than it did in the non-saline environment. Combined data for the 2 years gave positive correlations between grain yield and plant height, number of heads per unit area, and straw yield in both non-saline and saline environments. Since there were significant differences between barely genotypes in a number of growth and yield characteristics in both environments, it should be possible to develop improved barley cultivars for both non-saline and saline environments using plant breeding techniques.

Pyrite-organic matter relationships: Currant Bush Limestone, Georgina Basin, Australia

The relationship between the TOC (total organic carbon) and S (pyritic sulphur) contents of some organic-rich (TOC 3–14%) silty limestones and calcareous siltstones from the Cambrian Currant Bush Limestone of the Georgina Basin, Australia, is similar to that of euxinic sediments, but could also indicate deposition in a non-saline environment. However, such conditions are not easily reconciled with the shallow equatorial epeiric sea in which the formation is considered to have been deposited. The relationship can alternatively be explained by the relatively low Fe content of the sediment being the main limiting factor in pyrite generation, coupled with a slightly increased degree of pyritization with increased TOC. The relationship between the TOC and S contents of organic-poor (TOC 0.2–2.4%) samples from the same formation is similar to that of normal marine sediments, but the Fe content is probably also the major controlling factor on pyrite generation. These interpretations demonstrate that in using TOC and S contents to aid in reconstruction of depositional environments, it is important to check whether Fe content could have been the limiting factor in the formation of pyrite, even in sediments with only moderate carbonate contents.

Effect of Salinity on Rhizobium Growth and Survival

This study examines the effect of salinity on the growth and survival of Rhizobium spp. in culture media and soil. Eleven isolates from saline and nonsaline environments were compared. The growth (mean doubling time) of all strains and species tested decreased when the electrical conductivity of the culture medium (yeast extract-mannitol) was raised from 1.2 mS cm to 6.7 mS cm (15% seawater equivalent) or to 13.1 mS cm (28% seawater equivalent). Three of eleven strains failed to grow at 13.1 mS cm. Although growth was affected by salinity, four strains selected from the growth rate study could survive in extremely high concentrations of salt. Two strains with growth rates sensitive to salt and two strains with growth rates relatively unaffected by salt were inoculated into solutions with electrical conductivities of up to 43.0 mS cm (92% seawater equivalent). Not only did all four strains survive the initial osmotic shock (at 5 h after inoculation), but it was not until 27 days after inoculation that the sensitive strains exhibited a significant reduction in viable numbers. The salt-tolerant strains survived for more than 65 days with no reduction in viable counts. The interaction between soil moisture tension and soil salinity in relation to Rhizobium survival in gamma-irradiated soil was also examined. Six treatment combinations were used, ranging from -0.1 bars and 0.2 mS cm to -15 bars and 12 mS cm. Sensitive strains declined from 10 to 10 organisms per g of soil after 84 days of incubation at -15 bars and 12 mS cm. Tolerant strains survived for the same period with no loss in viable numbers. The results of these experiments indicate that many strains of Rhizobium can grow and survive at salt concentrations which are inhibitory to most agricultural legumes. The emphasis of research concerning the effects of salinity on symbiotic nitrogen fixation should, therefore, be directed to aspects of the symbiosis other than the survival of the Rhizobium spp.

Plant Communities of Saline Soils at Lincoln, Nebraska

The plant communities and their relationships to saline soils are described. A relationship is shown between an increase in salinity and decrease in cover of several species. Field observations indicate that the species which tolerate the highest salinities are capable of growing normally in low to nonsaline environments. This study area represents the southernmost extension of a stable Salicornia rubra community in the prairie region of the United States. A theory of tolerance to extreme environments is presented.

PRELIMINARY STUDIES ON THE MICROFLORA OF A HIGHLY SALINE SOIL

Most of the ecological studies on the microflora of natural saline environments have been carried out in water reservoirs (2, 3, 6). On the basis of these studies it is generally accepted that salt-dependent and salt-resistant microorganisms are widespread in nature and Iilay even be found in non-saline environments (10). In contrast to these findings it has been shown by many authors that various chemical transformations carried out by soil microorganisms are strongly inhibited by the addition to the soil of relatively sinall amounts of salts (1, 4, 5, 7, 8). The data presented in this note suggest that highly saline soils are not inhabited as a rule by halophilic or salt-resistant microorganisms. A highly saline, hydrohalomorphic soil near the Red Sea was studied. In this region, rainfall amounts to 30 mm per annuni, and the temperature in winter varies between 16 and 22 C and in tlie summer between 27 and 41 C. Because of constant evaporation, salt content varies in this soil from 25 to Soy0 on the surface to 1.5 to 2y0 a t 50-cm depth. The soil is constantly moistened by high level ground water. Some of its properties are presented in Table I . The microorganisms present in tliis soil a t various depths were counted using soil extract agar with and without sodium chloride, and after an incubation period of 6 weelcs a t 30° C. The results are summarized in Table I. Ilighest counts (32,600 illicroorganisms per g) were obtained a t the soil surface. However, even these counts were surprisingly low as compared with non-saline