Biodegradation of glyphosate herbicide in vitro using bacterial isolates from four rice fields

Glyphosate is a compound used as herbicide in the control and/or killing of grasses and herbaceous plants. It can be used in no-till agriculture, to prepare fields before planting, during crop development and after crop harvest. Because of its toxicity to non-target organisms, there is need to decontaminate glyphosate contaminated soils and bioremediation is a very useful alternative to conventional cleanup methods. The success of this will depend on isolating bacteria with the ability to degrade glyphosate in achanging environment. The abilities of five bacterial species (Escherichia sp, Azotobacter sp., Alcaligenes sp., Acetobacter sp. and Pseudomonas fluorescens) to degrade glyphosate herbicide under varying environmental conditions were evaluated in this study. The isolates were screened forglyphosate utilization using mineral salt medium containing glyphosate as carbon and/or phosphorus source. Of the five bacterial isolates, P. fluorescens and Acetobacter sp. showed the capacity to utilize glyphosateefficiently and were therefore used for further biodegradation studies. Time course of growth of the isolates on mineral salt medium containing glyphosate showed that both grew significantly (P < 0.05). Microbial growth during the study was monitored by measuring the optical density at 660 nm. The comparative effects of glyphosate as carbon and/or phosphorus source on the growth of the isolates showed that there was significant (P < 0.05) growth in the medium containing glucose and glyphosate. The effects of different concentrations of glyphosate on the growth of the isolates (P. fluorescens and Acetobacter sp) were evaluated. Significant (P < 0.05) growth was observed at lower concentrations (7.2 - 25 mg/ml) of glyphosate. No inhibition of growth was observed at high concentrations (100 - 250 mg/ml), indicating that the isolated bacteria can tolerate up to 250 mg/ml of glyphosate. However, there was subsequent decrease in growth of both isolates as the concentration of glyphosate increased. This study showed that P. fluorescens and Acetobacter sp. exhibited a high capacity to efficiently degrade glyphosate under the environmental conditions studied. Thus, the organisms can be exploited for biodegradation of glyphosate and should be studied for their ability to degrade other organophosphates

Effect of Different Steeping Conditions on the Peroxidase Activities of Some Improved Sorghum Varieties

In order to evaluate the impact of duration and the incorporation or  otherwise of air rest during steeping on the peroxidase activities of  sorghum grains, five improved varieties were studied. Steeping durations used ranged from 0 (raw grains) to 72 hours, in two formats: with air rest and without air rest. Results obtained showed that among the raw grains which were the control experiment, variety SK5912 gave the highest  peroxidase activity, followed by variety KSV 8 while variety CSRO2 had the least peroxidase activity. During steeping, we observed that in almost all cases, higher peroxidase activities were obtained with air rested sorghum grains than those without air rest. In terms of how the different varieties compared during steeping, we found that variety KSV 8 gave the highest peroxidase activity at both with and without air rest regimes in all the steeping periods used. Also, we observed that in all cases, the highest increase in peroxidase expression was obtained during the first 6 hours of steeping, shown by a steep rise of over 50% increase in activity. The other steeping times following the first 6 hours however showed just gradual  increases in peroxidase over the period of sorghum. The major significance of this result is that although increasing duration showed increased  peroxidase activities, such increases were less jumpy than those obtained during the first 6 hours. Therefore, long steeping times may not  necessarily be very beneficial, with the added benefit that costs associated with long steeping durations may be avoided.Key words: Sorghum, cereals, peroxidases, enzymes, steeping, germination, air rest

The effects of calcium regulation of endosperm reserve protein mobilization of the Nigeria sorghum cultivars, ICSV 400 and KSV 8 during malting

The effects of steep liquor calcium ion on sorghum endosperm reserve protein mobilization were evaluated using two improved Nigeria sorghum cultivars (ICSV 400 and KSV 8). The key protein modification factors evaluated were free amino nitrogen (FAN), total non protein nitrogen (TNPN) and soluble protein of cold water extract (CWS-P). Ca2+ treatment highly significantly (P < 0.001) repressed FAN development in both sorghum cultivars ICSV 400 and KSV 8. TNPN accumulation significantly enhanced in ICSV 400 by Ca2+ treatment in contrast to KSV8 malts which showed 23 to 69% repression. Similarly, Ca2+ treatment was effective in stimulating peptide accumulation in ICSV 400 at all levels of treatment indicating that the enhancement of TNPN accumulation in this cultivar was derived mainly from the stimulation of peptide accumulation. KSV 8 in contrast showed highly significant repression of peptide accumulation. Protein solubilisation, soluble protein accumulation and cold water soluble protein modification in both cultivars were all highly significantly repressed by Ca2+ treatment; although, ICSV 400 appeared to be better modified. Carboxypeptidase development was stimulated significantly by Ca2+ treatment in both cultivars. Existence of multiple high points in  carboxypeptidase activity suggests heterogeneity of this enzyme in sorghum while Ca2+ treatment caused reduced proteinase development in ICSV 400, the enzyme activity was enhance in KSV 8 albeit marginally.Key words: Sorghum malt, steep water Ca2+ treatment, modification, free amino nitrogen, total non protein nitrogen, carboxypeptidase

Calcium regulation of carbohydrate modification in sorghum

Two improved Nigeria sorghum cultivars (KSV 8 and ICSV 400) were used to evaluate the effects of steep water Ca2+ treatment on carbohydrate modification in sorghum. The response of all the carbohydrate mobilization indicators evaluated [- and - amylases, diastatic activity (DP), extract andcold water soluble carbohydrates (CWS-carbohydrates)], to steep water Ca2+ treatment was highly significantly (p 0.001) cultivar and steep water Ca2+ treatment dependent. In contrast to KSV 8, Ca2+ treatment generally caused significant repression of -amylase development in ICSV 400. Development of -amylolytic activity in KSV 8 was however, significantly repressed by Ca2+ treatment. Interestingly, - amylase activity constituting well over 80% of total diastatic activity was attained in ICSV 400 grainssubjected to 100 ppm Ca2+ treatment. Hot water extract (HWE) showed statistically insignificant (p 0.1) linear variation with Ca2+ treatment. Although Ca2+ treatment significantly (p .001) repressed  CWS carbohydrates in both cultivars, significantly higher CWS-carbohydrates and HWE were released in ICSV 400 for each DP unit than the corresponding DP in KSV 8 malts would permit. Thus, suggesting important roles for factors other than DP, possibly proteolysis, in determining HWE and  CWS carbohydrates. The benefits of reduced kernel growth and malting loss were neutralized by the general repression of carbohydrate modification indices for both cultivars

Incidence and pathogenicity profile of Listeria sp. isolated from food and environmental samples in Nsukka, Nigeria

Samples of beef, pork, goat meat, poultry, fish and vegetables purchased from a local market located in Nsukka, Enugu State, Nigeria were examined for the presence of Listeria species. Surface swab samples taken from butchers’ tables as well as soil samples from the field where cows and pigs were kept before slaughter were examined. Listeria species were isolated from all samples except the pork and goat meat samples. The highest incidence (100%) was observed in the soil and surface swabsamples, respectively, followed by the vegetable samples (85%) and the beef samples (80%). Only Listeria monocytogenes and Listeria ivanovii were pathogenic to test animals causing death within five days. L. monocytogenes induced pathological changes characterized by abscesses in the liver, pericarditis and frank haemorrhage in the kidneys. The most notable change was the accumulation of mononuclear cells in the loose connective tissue surrounding the bile ducts. This study shows thatthere is a high incidence of listerial organisms in various key elements of the Nigerian environment, including soil and foods of both animal and plant origin, which may pose a health risk for high-risk individuals. The study goes further to establish the major target organs of attack of the pathogenic Listeria species

Preliminary studies on the endo-xylanase and acetyl esterase of Clostridium thermohydrosulfuricum (JW 102)

Clostridium thermohydrosulfuricum (JW102) produced low levels of xylanase in mineral medium containing yeast extract and beechwood xylan. Production of xylanase was highest at growth temperatures of 62 – 64oC. Both xylan and xylose supported acetyl esterase production. Xylose, as sole carbon source, supported the production of slightly more acetyl esterase than xylan, while enzyme produced in the presence of xylan was relatively more stable in the fermentation medium, maintaining over 80% of peak activity after 20 hours. Acetyl esterase activity was highest at assay pH of 6.5. At pH 5.5 and 6.0, enzyme activity was, respectively, 5% and 22% of that recorded at pH 6.5. Key Words: Hemicellulases, Clostridium thermohydrosulfuricum, xylanase, acetyl esterase, beeechwood xylan. Bio-Research Vol.1(2) 2003: 1-

Screening of malting sorghum samples for lactic acid bacteria with potentials for antimicrobial activity

Three varieties of sorghum grains (SK 5912, KSV 400 and KSV 8) undergoing malting process were screened for lactic acid bacteria (LAB) with antimicrobial activity and characterized using standardmethods. Out of fifty-seven lactic acid bacteria isolates, eighteen isolates with antimicrobial producing potential were selected for further study. The isolates displayed significant (p < 0.05) inhibitory activityagainst two indicator strains Escherichia coli ATCC 111755 and Staphylococcus aureus ATCC 12600. Eleven of these inhibitor-producing isolates secreted inhibitory compounds that were sensitive tocatalase while compounds from the other seven isolates continued to display inhibitory effect against the indicator strains after treatment with catalase. The proteinaceous nature and inactivation bycatalase of these inhibitory compounds from the seven bacteria identified them as bacteriocins. Based on standard biochemical and microbiological tests, the isolates were tentatively identified as belonging to Lactococcus spp., Leuconostoc spp., Lactobacillus spp. and Streptococcus spp. However, three isolates (GS3A, S6A and S10B) were tentatively identified as Lactobacillus reuteri, Lactobacillusfermentum and Lactobacillus acidophilus, respectively. LAB isolated from three varieties of sorghum grains undergoing malting exhibited the ability to produce bacteriocin and hydrogen peroxide

On the pH and Osmotic Stress Tolerance of High Ethanol Tolerant Palm Wine Saccharomyces Yeast Isolates

Saccharomyces yeast strains Y13, Y522 and Y1189 isolated from fermenting palm wine juice showed marked differences in their optimum growth pH and possessed osmotolerance comparable to established industrial yeast strains. Shifts in medium pH beyond the growth optimum elicited obvious reductions in growth rate as depicted by the decrease in mean log growth rate (K) and influenced the response of the test yeasts to osmotic stress. Key Words: Osmotolerance, Ethanol tolerance, Osmotic stress, Saccharomyces Bio-Research Vol.2(1) 2004: 1-

Selection and characterisation of high ethanol tolerant Saccharomyces yeasts from orchard soil

Six yeast strains with different levels of ethanol tolerance were isolated from orchard soil. Out of the six isolates, isolate Orc 6 showed the highest ethanol tolerance (20%) while isolates Orc 2 and Orc 11 had15% ethanol tolerance. High level ethanol tolerant Saccharomyces yeast, Orc 6, was investigated for its potential application in ethanologenic fermentations. Data presented in this study revealed that Orc 6 yeast isolate tolerated osmotic stress above 12% (w/v) sorbitol and 15% (w/v) sucrose equivalent of osmotic pressure thus exhibiting superior osmotolerance than the reference production wine yeast strain. Invertase activity was also higher for Orc 6 yeast when grown in both sorbitol and sucrose media. Sorbitol increased yeast sedimentation rate in contrast to sucrose. Generally, the new yeast strain, Orc 6, showed superior fermentative performance compared to the reference production yeaststrain