Total Heterotrophic Count Research Articles

Treated agro-industrial wastewater irrigation of tomato crop: Effects on qualitative/quantitative characteristics of production and microbiological properties of the soil

A comparative study was carried out to evaluate the effects of two water irrigation sources on the quality and microbiological safety of tomato plants and fruit, and on the microbiological soil properties: irrigation with groundwater (GW) and with treated agro-industrial wastewater (TW). In a field experiment in southern Italy (Apulia region), the physico-chemical characteristics of the irrigation waters and the fruit quality parameters were determined. Escherichia coli, fecal Enterococci and Salmonella spp. were also monitored in the irrigation waters, tomato plant and fruit, and root-zone soil. Bacteriological analysis for total heterotrophic counts (THCs) were determined for plant, fruit, and soil samples. The irrigation water source did not significantly affect yield quantitative traits. However, with GW, the marketable fruit yield was higher than with TW (∼82 vs. ∼79Mgha−1, respectively). For both irrigation treatments, the most important qualitative parameters that characterize the processing tomato fruit (i.e., dry matter content, pH, soluble solid content, color parameters) were in agreement with reports in the literature. For the microbiological results, the mean levels of E. coli and fecal Enterococci were 4408 and 3804CFU 100ml−1, respectively, for TW (above the Italian guidelines for TW re-use). For the tomato plant and fruit, no E. coli isolated in either, and fecal coliforms and THC were not influenced by the irrigation waters (P>0.05). Total bacterial enumeration by quantitative PCR was lower in soil irrigated with GW, than TW (3.69 vs. 4.02, ×106, respectively). Moreover, soil microbial community patterns substantially differed between the two water treatments. These data show that while fecal indicators are not affected, the community composition and dynamics of the whole bacterial population in soil is influenced by the different qualities of these waters used for irrigation.

Bacteriological and chemical properties of soil amended with fermented poultry bird feather

Huge amount of poultry wastes are generated annually in developing nations, of which end up in our environment. Feather as a poultry waste have caused environmental concerns in many of these countries. In this research work, poultry feather was used to study its effects on bacteriological and chemical properties in agricultural soil. The feathers collected were grinded, sterilized and fermented before mixing it with soil. Total heterotrophic counts of colonies were enumerated from the soil samples. Isolates were characterized based on morphological and series of biochemical tests. Soil chemical analysis for pH, carbon, nitrogen, phosphorus, calcium, potassium was also carried out. The heterotrophic bacteria count of the treated soil had the highest count in the range of 1.54 x106 to 2.02 x106 (CFU/g) as against the control soil with 1.24 x106 (CFU/g). The bacteria identified from these samples were Bacillus sp., Proteus sp., Staphylococcus sp. and Actinomyces sp. Actinomyces sp. was isolated only after three weeks of treatment with the feather while all other bacteria were also present in the control soil but at elevated levels based on heterotrophic bacteria count in the treated soil. The soil chemical analysis of the treated soil had high amount of mineral (Organic carbon 1.10 %, nitrogen 0.09%, phosphorus 0.53±0.02 mg/kg, magnesium 0.45±0.01 mg/kg as against the control (Organic carbon 0.26%, nitrogen 0.05%, phosphorus 0.30±0.10 mg/kg, magnesium 0.45±0.01 mg/kg) and their pH is almost near neutrality, 7.12 and 7.08 respectively. The result suggested that soil treated with poultry feather increased the plate count of Bacillus sp, Proteus sp, Staphylococcus sp and Actinomyces sp. Poultry feather which is a waste by-product can provide essential nutrients for the survival of soil microorganisms, plant growth and therefore can be exploited as biofertilizer.Keywords: Bacillus sp., biofertilizer, fermentation, keratin, poultry waste

Microbiological, coliphages and physico-chemical assessments of the Umgeni River, South Africa

The water quality of Umgeni River in KwaZulu-Natal (South Africa) was investigated from April 2011 to January 2012. Indicator bacterial populations, physico-chemical properties, heavy metal contaminants and the presence of coliphages were determined according to standard protocols. The results showed that all sampling points failed to comply with the set guidelines for turbidity, total coliform, faecal coliform and total heterotrophic counts. Salmonella spp., Shigella spp. and Vibrio cholerae were also detected in all the water samples. The somatic coliphages and F-RNA coliphages were detected more frequently in the lower reaches of the river during summer. Temperature, electrical conductivity and pH were found to have positive relationships with the microbial communities especially in the lower catchment area during spring and summer indicating the impacts of various anthropogenic activities in the surrounding areas.

Effects of Heavy Metals on Microbial Function in Water and Sediment around Abonnema Island at Lower Sombriero River, Nigeria

Aims: The interrelationships between heavy metals Lead (Pb), Copper (Cu), Cadmium (Cd), Chromium (Cr) and Zinc (Zn) and microorganisms in sediment and overlying water along the shoreline of Abonnema Island were investigated by determining the levels of Carbon Dioxide (CO2), Ammonia (NH3), and Sulphate (SO4). Study Design: Water and sediment samples were collected from seven stations approximately 500 metres apart using plastic containers and Erkman grab sampler respectively. Glucose, palm oil, and cowbell powdered milk were separately added to each set of water and sediment samples and each inoculated with 0.05mg/l, 0.15mg/l and 0.5mg/l of copper, zinc, lead, chromium and cadmium and incubated for seven days at about 30oC. Place and Duration of Study: The study was undertaken in the Institute of Geosciences and Space Technology, University of Science and Technology, Port Harcourt, Nigeria between January 2007 and November 2008. Methodology: Heavy metals were determined using Atomic Absorption Original Research Article British Journal of Applied Science & Technology, 4(2): 399-422, 2014 400 Spectrophotometer. Carbon dioxide, Ammonia, Sulphate in water and sediment were determined by titration, phenate, turbidimetric and KH2PO4 extraction methods using Spectrophotometer. Total heterotrophic counts were carried out on Nutrient agar plates. Total coliform and Total faecal coliform counts were determined using the most probable number (MPN) technique using Mac – Conkey broth. Petroleum degrading bacteria was isolated in petroleum agar. Results: The results showed that heavy metals had stimulatory effect on microbial functions in some cases and inhibitory effect in others. The stimulatory effect on CO2 respiration was more in the water than in the sediment while the stimulatory effect on NH3 respiration was more in the sediment than in the water. The stimulatory effect on SO4 respiration was more in the sediment than in the water. The inhibitory effects on NH3 and SO4 respiration were more in the water than in the sediment. The concentrations of CO2 and SO4 were within permissible limit while NH3 exceeded permissible limit. Conclusion: The inhibitory effects of the heavy metals on the levels of CO2, NH3 and SO4 resulting from the biodegradation of carbohydrate (glucose) and protein (cowbell powdered milk) show that the rate of cycling of carbon, Nitrogen and Sulphur in the coastal waters is being affected by the heavy metals. Thus effluents should be treated before discharge into the river while direct discharge of other heavy metal containing wastes into the river should be discouraged.

Assessment of Floristic, Microbial Composition and Growth of Sphenostylis stenocarpa (Hochst Ex A. Rich) in Soil from Two Dumpsites in Benin City, Nigeria

Survey of dumpsite plant composition, assessment of rhizosphere microorganisms and growth performance of Sphenostylis stenocarpa grown on two dumpsite (CAPITOL and NITEL ROAD) soils in Benin City was investigated. Control treatment was top soil. A total of 9 and 30 flora were observed at the CAPITOL and NITEL ROAD dumpsites respectively. Analysis of the rhizosphere soils of the plants grown in dumpsite soils at different amendments showed a total heterotrophic bacterial count ranging from 1.57 x 104 to 4.18 x 104cfu/g and a total heterotrophic fungal count in the various rhizosphere soils ranged from 5.05 x 103 to 1.68 x 104cfu/g. The bacterial isolates from the rhizosphere soil samples were Arthrobacter sp., Bacillus sp, Pseudomonas sp., Escherichia coli, Enterobacter sp., Klebsiella sp., Micrococcus sp. and Staphylococcus sp. The fungal isolates were Aspergillus sp, Mucor sp, Fusarium sp, Penicillium sp, Trichoderma sp. and Saccharomyces sp. Bacillus sp., Pseudomonas sp., Penicillium sp. and Aspergillus sp. Aspergillus sp. 100 % (present in all dumpsite soils analyzed) had the highest frequency of occurrence amongst the isolates.Percentage seedling emergence was significantly reduced from 86.67± 13.33 % - 100.00 ± 0.00 % in control (top) soil to 60.00 ± 0.00 % to 93.33 ± 6.67 % in CAPITOL dumpsite soil. Shoot height at 6 weeks after planting (WAP) was significantly (p < 0.05) increased from 78.33± 18.53 cm in the control soil through 131.50 ± 18.79 cm in the CAPITOL dumpsite soil to 186.33 ± 13.68 cm in NITEL road dumpsite soil, all without amendment. Number of leaves at 6 WAP increased on addition of FYM in both soil types. Chlorophyll content was not significantly different (p > 0.05) from control plants. Leaf area in both dumpsite soils was found to be significantly different (p < 0.05) from the control soil but leaf area increased on addition and increase in amendment in both soil types. In all parameters observed, it was noted that the control treatment did better than the plants grown in the dumpsite soils with increased amendment..

Hygienic surveillance in swimming pools: Assessment of the water quality in Bologna facilities in the period 2010–2012

In the three-year period 2010–2012, 80 public swimming facilities in the metropolitan area of Bologna (Emilia Romagna Region, Italy), including 144 pools (69 indoor, 75 outdoor), were monitored to assess the microbiological and chemical water quality, after about ten years of implementing the new Italian guidance which introduced the principles of internal safety plans in the surveillance of swimming pools. According to the Italian guidance, water samples were collected from supply water (370 samples), pool water (645), and recirculating water entering the pool (307). The samples of supply water always conformed to the microbiological limits for drinking water. The pool water did not conform to the Italian legal requirements in around 16% of indoor pools and 25% of outdoor pools. In 65% of non-compliant samples, only one parameter exceeded the required standards. The microorganisms of faecal origin were isolated very rarely (Enterococci in less than 2% of samples) and pH and residual chlorine showed good compliance in pool water, implying an efficient management of the internal control. The inlet water exceeded the required standards in about 36% and 50% of samples, respectively in indoor and outdoor pools. However, 83.6% of the corresponding samples of pool water met the required limits. The microbiological incongruities were prevalently due to high levels of total heterotrophic counts (THCs) and Pseudomonas aeruginosa, and were indicative of bacterial colonization of the filters. The sampling of inlet water can thus be indicated as a critical control point for checking the correct functioning of the filters. The non-conformity of samples led to pool closure only in 1.5% of cases. In the other cases, the operators were officially invited to perform the corrective measures previously established in the plan of risk assessment. On the whole, the approach based on internal safety plans produced satisfactory results in terms of pool water quality, demonstrating the effective working of the internal system of analysis and management of risks.

BIOREMEDIATION OF PETROLEUM HYDROCARBON-POLLUTED MANGROVE SWAMPS USING NUTRIENT FORMULA PRODUCED FROM WATER HYACINT (<I>EICCHORNIA CRASSIPES</I>)

Laboratory-scale studies were carried out using a nutrient formula produced from Eicchornia crassipes plant to achieve bioremediation of crude oil impacted mangrove soil. In a 70 day study, the culturable heterotrophic bacterial population of the Eichhornia crassipes recipe increased from 6.26×105 Cfu/g to 2.69×107 Cfu/g. The control set-up had its total culturable bacterial count increased from 5.76×105 Cfu/g to 1.24×106 Cfu/g. Statistical analyses showed significant difference for the two conditions (p ≥ 0.05). The total culturable heterotrophic fungal count in the Eichhornia crassipes recipe treatment increased from 5.36×105 Cfu/g to 2.50×107 Cfu/g respectively. The total culturable hydrocarbon utilising bacteria in Eichhornia crassipes treated polluted mangrove soil increased from 2.52×104 Cfu/g to 3.81×107 Cfu/g. Statistical analyses showed significant difference at p ≥ 0.05 level for the two conditions (Eicchornia crassipes nutrient treated soil and control). The total culturable hydrocarbon utilising fungal counts increased significantly for both the control and Eichhornia crassipes treatment. There was no regular trend in pH changes in all the conditions. The conductivity value of the Eichhornia crassipes recipe treated soil decreased progressively. Phosphate, nitrate, %total organic carbon, Total Hydrocarbon Content (THC). Studies using Gas chromatographic analyses showed that in the Eichhornia crassipes recipe treated polluted mangrove soil, 0, 58.92 and 75.36% were lost at zero hour, 28th day and 70th day respectively. In addition, in the control experimental set-up, 0, 7.14 and 13.42% of TPH were lost at zero hour, 28th day and 70th day respectively. There was no significant difference between the control experiment and Eichhornia crassipes (p = 0.054). The use of organic nutrient sources such Eichhornia crassipes recipe/nutrient powder is of good use as source of limiting nutrient needed for bioremediation of crude oil impacted medium.

Bacterial species isolated from water bodies in Rivers and Bayelsa States are possible aetiological agents of diarrhoea

Background : The role of water in the transmission of diarrhoea has been established. The World Health Organization (WHO) reported that diarrhoea disease were among the 10 major causes of death in young children in 11 African, Asia and South American countries. Aim : To investigate the incidence of Salmonella and Vibrio species as aetiological agents of diarrhoea in water bodies in Rivers and Bayelsa States. Methods : A total of twenty water samples were collected from rivers and cultured for the various microorganisms.The total heterotrophic counts were determined by Standard Plate Count (SPC) method. Salmonella and Vibrio species were enumerated by an enrichment procedure in Selenite F broth and Alkaline Peptone water (APW) respectively; cultured on Bismuth sulfite agar (BSA) and Thiosulphate citrate bile salt sucrose (TCBS) agar selective for salmonella and vibrio species respectively. The total coliform counts was determined and the Most Probable Number (MPN) using the multiple tube fermentation technique. Results : The study revealed isolates with various percentage occurrences which include Vibrio (12.1%) and Salmonella (33.3%). Among the coliforms were Escherichia coli (33.3%), Klebsiella (22.2%), Enterobacter (33.3%) and Citrobacter (11.1%).MPN values for enumeration of coliforms ranged from 80/100 ml to = 16,000/100 ml of the water samples analysed. Total heterotrophic count per milliliter of the original water sample ranged between 1.0 × 106 and 3.0 ×108 cfu/ml. Conclusion : The water sources examined have proved to be potential sources of diarrhoea organisms and also could lead to disease outbreak because of the significant number of these organisms in these water bodies.

Assessment of Water Quality in Asa River (Nigeria) and Its Indigenous Clarias gariepinus Fish

Water is a valued natural resource for the existence of all living organisms. Management of the quality of this precious resource is, therefore, of special importance. In this study river water samples were collected and analysed for physicochemical and bacteriological evaluation of pollution in the Unity Road stream segment of Asa River in Ilorin, Nigeria. Juvenile samples of Clarias gariepinus fish were also collected from the experimental Asa River and from the control Asa Dam water and were analysed for comparative histological investigations and bacterial density in the liver and intestine in order to evaluate the impact of pollution on the aquatic biota. The water pH was found to range from 6.32 to 6.43 with a mean temperature range of 24.3 to 25.8 °C. Other physicochemical parameters monitored including total suspended solids, total dissolved solids, biochemical oxygen demand and chemical oxygen demand values exceeded the recommended level for surface water quality. Results of bacteriological analyses including total heterotrophic count, total coliform and thermotolerant coliform counts revealed a high level of faecal pollution of the river. Histological investigations revealed no significant alterations in tissue structure, but a notable comparative distinction of higher bacterial density in the intestine and liver tissues of Clarias gariepinus from Asa River than in those collected from the control. It was inferred that the downstream Asa River is polluted and its aquatic biota is bacteriologically contaminated and unsafe for human and animal consumption.

Pollution studies on harbours and jetties in Nigeria

The distribution of bacteria in the surface waters and sediment of selected harbours and landing jetties in the city of Port Harcourt was investigated. Nine water and sediments samples were allocated on each trip and cultured for various organisms on the rainy and dry season. The total heterotrophic count of the water sample in the dry season ranged between 33 ± 7.4 and 62 ± 6.1 and between 38 ± 7.1 and 62 ± 19 CFU/ml in the rainy season. In the case of sediment samples, the THC of the dry season ranged between 31 ± 8.1 and 54 ± 20 CFU/g, while the count in the rainy season ranged between 24 ± 1.9 and 54 ± 19 CFU/g. Of the Vibrio species isolated, 3 (60%) were found to be Vibrio cholerae, while 2 (40%) were Vibrio parahaemolyticus, four isolates were also identified as Salmonella species. The high distribution of the bacteria which is of public health importance in the harbours/jetties, indicates pollution. Physiochemical parameters such as alkalinity, dissolved oxygen, temperature, pH, conductivity, total dissolved solids, salinity, chloride, biochemical oxygen demand (BOD) and heavy metal were investigated and showed significantly high values, which indicates pollution of the harbour. Key words: Bacteria, Port Harcourt, Vibrio.

Effect of Probiotics on Growth Performance of Koi Carp (Cyprinus carpio)

A 45-day feeding experiment was conducted to measure the effects of enhancing the diet of koi carp (Cyprinus carpio) fingerlings with lactic acid bacteria, Lactobacillus acidophilus (LAD) and/or brewer's yeast, Saccharomyces cervisiae (SCD). Fish with an average initial weight of 0.26g were fed one of four diets prepared for this study as follows: Diet 1 = basal diet (control); Diet 2 = basal diet + 0.5% LAD; Diet 3 = basal diet + 0.5% SCD; and Diet 4 = basal diet + 0.25% LAD + 0.25% SCD. Significantly (P < 0.05) highest growth rate was achieved in diet 3 followed by diet 4, diet 2, and diet 1. The highest gut microbial load and total heterotrophic count were also higher in diet 3 followed by diet 4, diet 2, and diet 1. Incorporation of 0.5% of brewer's yeast in the basal diet significantly (P < 0.05) improves growth performances and gut microbial load in koi carp.

Effect of different organic nutrient supplements on the total heterotrophic counts and diesel oil degradation in diesel polluted soil

The effect of graded quantities of different organic nutrient supplements on the total heterotrophic counts and diesel oil degradation in diesel-polluted soil was studied. Soil samples were mixed with different volumes of diesel to obtain heavy and moderate pollution, which was subsequently amended with different quantities of organic nutrient supplements. Total heterotrophic counts were determined at two weeks intervals for 16 weeks and the oil and grease content were determined at the beginning and at the end of the study. The result showed a general increase in microbial count with increase in the quantities of supplement. Poultry waste-amended samples had the highest count in all the samples followed by pig waste and cow dung-amended samples. Diesel oil degradation followed the same order with the highest percentage oil degradation obtained in poultry waste-amended samples. It therefore, showed that poultry waste is the best organic waste to be appliedin a biodegradation process.Keywords: Diesel oil, organic nutrients, biodegradation, heterotrophic microorganisms.

Characterization of arsenic-resistant bacteria from the rhizosphere of arsenic hyperaccumulatorPteris vittata

Arsenic hyperaccumulator fern Pteris vittata L. produces large amounts of root exudates that are hypothesized to solubilize arsenic and maintain a unique rhizosphere microbial community. Total heterotrophic counts on rich or defined media supplemented with up to 400 mmol/L of arsenate showed a diverse arsenate-resistant microbial community from the rhizosphere of P. vittata growing in arsenic-contaminated sites. Twelve bacterial isolates tolerating 400 mmol/L of arsenate in liquid culture were identified. Selected bacterial isolates belonging to different genera were tested for their resistance to osmotic and oxidative stresses. Results showed that growth was generally better under osmotic stress generated by arsenic than under that generated by NaCl or PEG 6000, demonstrating that arsenic detoxification metabolism also cross-protected bacterial isolates from arsenic-induced osmotic stress. After 32 h of growth, all arsenate at 1 mmol/L was reduced to arsenite by strains Naxibacter sp. AH4, Mesorhizobium sp. AH5, and Pseudomonas sp. AH21, but arsenite at 1 mmol/L remained unchanged. Sensitivity to hydrogen peroxide was similar to that in broad-host pathogen Salmonella enterica sv. Typhimurium wild type, except strain AH4. The results suggested that these arsenic-resistant bacteria are metabolically adapted to arsenic-induced osmotic or oxidative stresses in addition to the specific bacterial system to exclude cellular arsenic. Both these adaptations contribute to the high arsenic resistance in the bacterial isolates.

Study of Soil Microflora Indicating Pesticide Contamination of Cauvery River Belt in India

The usage of microbial responses as an indicator of herbicide toxicity in soil residue is well known. The present study is aimed to analyze the heterotrophic and pesticide degrading bacteria in sediment samples of Cauvery River bed, where the farmers are using methyl parathions as a potent pesticide in paddy and vegetable fields. We report, higher incidence of methyl parathion degrading bacterial population in the river bed which can able to utilize the pesticide at a concentration of 5μl/ml. The heterotrophic and methyl parathion degrading bacterial counts in soil sediment samples was carried out on monthly basis from Oct. 2007 to Nov. 2008. The total heterotrophic bacterial count was in the range of 12-20 × 10 4 CFU / gm and the total pesticide degrading bacterial count was 50-90 × 10 3 CFU/gm. Among the pesticide degrading bacterial population, Bacillus sp. was found to be dominant followed by Pseudomonas sp., Micrococcus sp. and Yersinia sp. No marked fluctuation was noticed in total heterotrophic count and pesticide degrading bacterial count irrespective of seasonal variation. The pesticide degrading ability was studied in presence of various parameters. The optimum temperature for the methyl parathion degradation was 37°C, pH7 and there was no change due to the increase in glucose level. Cauvery is one of the main riparian water sources in South India supporting the agrarian activities and susceptible for pesticide contamination due to run off from the agri-lands during monsoon season. The study indicates the presence of pesticide contamination in the riparian water which is the source for drinking and agricultural activity. Hence there is a need for an alternate pest management in this area as environmental protection point of view.

Study of soil microflora indicating pesticide contamination of Cauvery River belt in India

The usage of microbial responses as an indicator of herbicide toxicity in soil residue is well known. The present study is aimed to analyze the heterotrophic and pesticide degrading bacteria in sediment samples of Cauvery River bed, where the farmers are using methyl parathions as a potent pesticide in paddy and vegetable fields. We report, higher incidence of methyl parathion degrading bacterial population in the river bed which can able to utilize the pesticide at a concentration of 5μl/ml. The heterotrophic and methyl parathion degrading bacterial counts in soil sediment samples was carried out on monthly basis from Oct. 2007 to Nov. 2008. The total heterotrophic bacterial count was in the range of 12-20 × 10 4 CFU / gm and the total pesticide degrading bacterial count was 50-90 × 10 3 CFU/gm. Among the pesticide degrading bacterial population, Bacillus sp. was found to be dominant followed by Pseudomonas sp., Micrococcus sp. and Yersinia sp. No marked fluctuation was noticed in total heterotrophic count and pesticide degrading bacterial count irrespective of seasonal variation. The pesticide degrading ability was studied in presence of various parameters. The optimum temperature for the methyl parathion degradation was 37°C, pH7 and there was no change due to the increase in glucose level. Cauvery is one of the main riparian water sources in South India supporting the agrarian activities and susceptible for pesticide contamination due to run off from the agri-lands during monsoon season. The study indicates the presence of pesticide contamination in the riparian water which is the source for drinking and agricultural activity. Hence there is a need for an alternate pest management in this area as environmental protection point of view.

Microbiological quality of packaged drinking water brands marketed in Ibadan metropolis and Ile-Ife city in South Western Nigeria

Continuous increase in the sale and indiscriminate consumption of packaged drinking waters in Nigeria is of public health significance. One hundred and eight samples comprising 16 bottled and 20 sachet water brands purchased randomly all over Ibadan and Ile-Ife cities in South Western Nigeria were analysed for presence of bacterial indicators of water quality. Total heterotrophic bacteria plate counts (HPC) ranged from 2 to 150 for bottled water and 5 to 200 for sachet water brands. One brand of bottled water and eight brands of sachet water had mean HPC greater than 100 per ml millilitre water and thus fell below the United States Environmental Protection Agency (USEPA) and World Health Organisation (WHO) dinking water standard of 100 HPC per millilitre water. Total coliforms and Escherichia coli were detected in only one brand of bottled water. All brands of sachet water (100%) had total coliforms, four brands (20%) had presence of E. coli while Enterococcus faecalis was recovered from two (10%) of the brands. Most of the sachet water brands fell below WHO drinking water standards and are therefore of doubtful quality. Efforts need to be intensified in the monitoring of activities in this rapidly expanding industry with a view to raising standards.

Impact of commonly used agrochemicals on bacterial diversity in cultivated soils

The effects of three selected agrochemicals on bacterial diversity in cultivated soil have been studied. The selected agrochemicals are Cerox (an insecticide), Ceresate and Paraquat (both herbicides). The effect on bacterial population was studied by looking at the total heterotrophic bacteria presence and the effect of the agrochemicals on some selected soil microbes. The soil type used was loamy with pH of 6.0-7.0. The soil was placed in opaque pots and bambara bean (Vigna subterranean) seeds cultivated in them. The agrochemicals were applied two weeks after germination of seeds at concentrations based on manufacturer's recommendation. Plant growth was assessed by weekly measurement of plant height, foliage appearance and number of nodules formed after one month. The results indicated that the diversity index (Di) among the bacteria populations in untreated soil and that of Cerox-treated soils were high with mean diversity index above 0.95. Mean Di for Ceresate-treated soil was 0.88, and that for Paraquattreated soil was 0.85 indicating low bacterial populations in these treatment-type soils. The study also showed that application of the agrochemicals caused reduction in the number of total heterotrophic bacteria population sizes in the soil. Ceresate caused 82.50% reduction in bacteria number from a mean of 40 × 10(5) cfu g(-1) of soil sample to 70 × 10(4) cfu g(-1). Paraquat-treated soil showed 92.86% reduction, from a mean of 56 × 10(5) cfu g(-1) to 40 × 10(4) cfu g(-1). Application of Cerox to the soil did not have any remarkable reduction in bacterial population number. Total viable cell count studies using Congo red yeast-extract mannitol agar indicated reduction in the number of Rhizobium spp. after application of the agrochemicals. Mean number of Rhizobium population numbers per gram of soil was 180 × 10(4) for the untreated soil. Cerox-treated soil recorded mean number of 138 × 10(4) rhizobial cfu g(-1) of soil, a 23.33% reduction. Ceresate- and Paraquat-treated soils recorded 20 × 10(4) and 12 × 10(4) cfu g(-1) of soil, respectively, representing 88.89% and 93.33% reduction in Rhizobium population numbers. Correspondingly, the mean number of nodules per plant was 44 for the growth in untreated soil, 30 for the plant in the Cerox-treated soil, 8 for the plant in Paraquat-treated soil and 3 for the plant in Ceresate-treated soil. The study has confirmed detrimental effect of insecticide on bacterial populations in the soil. Total heterotrophic counts, rhizobial counts as well as the number of nodules of all samples taken from the chemically treated soils were all low as compared to values obtained for the untreated soil. However, the effect of the insecticide was minimal in all cases as compared to the effects of the herbicides on the soil fauna. Indiscriminate use of agrochemicals on farms can therefore affect soil flora and subsequently food production.

Seasonal dimethylsulfoniopropionate (DMSP) variability in Dona Paula bay

Data on temporal variations of total dimethylsulfoniopropionate (DMSP t) and the environmental factors that influence DMSP t concentrations are important in understanding the biogeochemical cycling of organic sulfur compounds. Annual and diurnal variations of DMSP t were investigated in relation to environmental variables at a fixed station in Dona Paula bay (west coast of India). DMSP concentrations were high in the day and low at night and ranged from 3.69 to 84 nM with a maximum at 17.00 h. The high concentrations of DMSP t during daytime closely followed that of Chl a concentrations. The DMSP utilizers averaged 0.8 ± 0.3 × 10 3 cells l −1 during night and 0.4 ± 0.1 × 10 3 cells l −1 during the day. The diel variation of DMSP t was influenced more by biological variables than hydrographic parameters. In the year-round study, the concentrations ranged from 0.69 to 15.8 nM. It was fourfold higher during the southwest monsoon season (13.4 ± 2 nM) and threefold higher during the post-monsoon season (9.96 ± 5 nM) compared to the pre-monsoon season (3.1 ± 1 nM). DMSP t concentrations showed temporal variability, both during diurnal and annual studies. Diatoms were identified as producers of DMSP in Dona Paula bay. Dinoflagellates also contributed during the non-monsoon seasons. Another factor involved in the variability of DMSP t was DMSP utilizing bacteria, which ranged from 1 to 10% of the total heterotrophic count.

Biodegradation of detergents by aquatic bacterial flora from Otamiri River, Nigeria

The utilization of Omo®, Jet® and Persil® detergents by aquatic bacteria isolates from Otamiri River at Nekede in Owerri North, Imo State, Nigeria was investigated. Identification tests for bacteria isolates from Otamiri River revealed them to belong to the genera Bacillus, Micrococcus, Escherichia, Enterobacter, Klebsiella, Psendomonas, Actinomyces, Corynebacterium, Serratia and Staphylococcus. Detergent utilization studies revealed total heterotrophic count of 3.38, 3.40, 3.36 and 5.35 log cfu/ml and 2.08, 2.20, 1.95 and 3.48 log cfu/ml obtained at 0 and 48 h for Omo®, Jet®, Persil® and control experiment, respectively. At 96 and 144 h, 2.37, 2.35, 2.25 and 2.47 log cfu/ml and 2.39, 2.37, 2.35, and 2.46 log cfu/m were obtained. While counts of 1.70, 2.37, 1.38 and 2.4 log cfu/ml were obtained at 192 h for Omo®, Jet®, Persil® and the control experiment, respectively. Of the nine bacterial isolates obtained from the river water, only Pseudomonas, Bacillus, Actinomyces, Corynebacterium and Staphylococcus were found to survive in the detergent water and possibly utilize the test detergents. Isolate specific detergent utilization test revealed these isolates to be capable of utilizing the test detergents in single and combined forms with Pseudomonas showing the highest ability while the least was observed for Staphylococcus. Statistical analysis revealed significant changes in optical density of detergent broth challenged with the test organisms, with the organism showing more ability to utilize, Omo® and Jet® than Persil® detergents. The result obtained, however, reveals the ability of natural aquatic bacterial Isolates to degrade detergents in aquatic ecosystem.

Effect of organic nutrient on microbial utilization of hydrocarbons on crude oil contaminated soil

The effect of organic nutrient (poultry manure) on biodegradation of soil (5 kg) contaminated with crude oil (50 g) was investigated for seven weeks. Four different test options were prepared namely; (i) 100 g of contaminated soil + 30 g of poultry manure; (ii) 100 g of contaminated soil + 60 g of poultry manure; (iii) 100 g of contaminated soil + 90 g of poultry manure; (iv) 100 g of contaminated soil only (control). The microbial degradation was monitored by the measurement of total heterotrophic count (THC), hydrocarbon utilizing bacterial count (HUB) and gravimetric loss of the crude oil with time. The cumulative THC of 6.9x107, 9.0x107, 1.03x108 and 3.1x107 cfu/g were recorded for test options (i), (ii), (iii) and (iv), respectively. The hydrocarbon utilizing bacterial counts (HUB) were 1.68x105, 1.63x105, 1.9x105 and 4.8x104 cfu/g for tests options (i), (ii), (iii) and (iv), respectively. There was a corresponding gravimetric hydrocarbon loss of 40.0, 45.26, 49.47 and 29.47% for test conditions (i), (ii), (iii), and (iv), respectively. The results of the study suggest that addition of organic nutrient (especially 90 g poultry manure) will further enhance microbial utilization of hydrocarbons. Key words: Biodegradation, crude oil, poultry manure.