Garba Uba | Jigawa State Polytechniic Dutse (original) (raw)

Papers by Garba Uba

Acrylamide contamination in food is mainly from raw material of plant-based origin. Acrylamide bi... more Acrylamide contamination in food is mainly from raw material of plant-based origin. Acrylamide biodegradation by soil bacteria is an important remediation process. Bacillus sp. strain ZEID-14, which had previously been identified and exhibited the ability to break down amides, was examined further to determine the crucial parameters that contribute to the optimum growth of acrylamide. The Box-Behnken design was used to optimize the previously identified three significant components (pH, incubation time and acrylamide concentration). The model was supported by the diagnostic plots including the half-normal, Cook's distance, leverage vs runs, residual vs runs, Box-Cox, DFFITS, and DFBETAS. Predicted optimal conditions were determined using "Numerical Optimisation" toolbox of the Design Expert software. Two optimal conditions were tested. The model predicted a maximum growth of 10.686 (95% C.I., 10.458 to 10.913) which was verified through experimental results with a growth of 11.257 (95% C.I., 11.051 to 11.462) with the actual results being near to the predicted values but was significantly higher than the predicted values. The second numerical optimization gave a solution with a predicted maximum growth of 9.305 Log CFU/mL (95% C.I. from 9.011 to 9.614) which was verified through experimental results with a growth of 9.978 Log CFU/mL (95% C.I. from 9.830 to 10.126) with the actual results were also significantly higher than the predicted values. The RSM exercise gave far better growth on acrylamide than OFAT with a higher response of about 2 log CFU/mL unit indicating the utility of RSM over OFAT in the optimization of growth of this bacterium on acrylamide.

Acetamiprid is a kind of broad-spectrum systemic pesticide that works on the nicotinic acetylchol... more Acetamiprid is a kind of broad-spectrum systemic pesticide that works on the nicotinic acetylcholine receptor. This chemical disrupts the transmission of a signal and causes a buildup of neurotransmitters, which leads to pests being paralyzed and eventually dying as a result. The calibration curve for the detection of acetamiprid utilizing a gold nanoparticle-based visual aptasensor showed a sigmoidal shape profile; hence, the 5-PL or 4-PL model should be used to fit the data rather than a linear model. The result of the error function analysis shows that the simpler 4-PL model is more reliable having smaller AICc, R 2 and adjR 2 , values whilst the other error functions such as RMSE, BIC and HQF, BF and AF values indicated that the 5-PL model shows that the 5-PL model was marginally superior to the 4-PL. As the 95% confidence interval overlap, the IC50 values were deemed not significantly different, and when this occur, based on Occam's razor, the model having a lower number of parameters, which was 4-PL, should be chosen instead. The 4-PL equation produced a value for the LOD of 0.159 mM, and the confidence interval for 95 percent of the results ranged from 0.132 to 0.177. According to the first study, the LOD was 3.81 mM, and the calculated LOD using 4-PL model with pooled standard deviations was much more sensitive. This indicates that utilizing only the linear portion of a sigmoidal curve to report the LOD values gave a less sensitive value than it should be.

BIOREMEDIATION SCIENCE AND TECHNOLOGY RESEARCH, Jul 31, 2022

The formulation of hypotheses and the recommendation of experiments as the subsequent stages of t... more The formulation of hypotheses and the recommendation of experiments as the subsequent stages of the research process are both brought about as a result of the utilization of complicated computer models that make it possible to represent intricate biological processes. Because these systems rely on random data, this is a necessity for all parametric statistical assessment procedures. When the diagnostic tests reveal that the residuals make up a pattern, there are a few different treatment choices available to choose from. Two of these alternatives include running a nonparametric analysis or switching to a new model. In this study, we use the Wald-Wolfowitz runs test as a statistical diagnosis tool to determine whether or not the randomization conditions have been met. The runs test found that there were 5 total runs, although the randomness assumption predicted 7.46 runs. The null hypothesis is not rejected since the p-value is greater than 0.05; this suggests that there is no convincing evidence of the residuals' non-randomness; rather, the residuals represent noise. In addition, the Grubb's outlier test shows no indication of an outlier, further corroborate the scenario of the adequacy of the modified Gompertz model used in the fitting of the growth of Shigella flexneri.

JOURNAL OF BIOCHEMISTRY, MICROBIOLOGY AND BIOTECHNOLOGY, Jul 31, 2020

Aflatoxins are mycotoxins produced by fungi of the genus Aspergillus that contaminate food produc... more Aflatoxins are mycotoxins produced by fungi of the genus Aspergillus that contaminate food products such as cereals leading to serious health and economic consequences. In order to assess the level of fungal contaminants and the presence of aflatoxins in such products, five (5) different cereal samples comprising of rice, maize, millet, wheat and sorghum were purchased each from two major markets within Kaduna metropolis. The samples were assessed for fungal contaminants using tenfold serial dilution and cultured appropriate dilutions using pour-plate technique. Aflatoxins were detected using Enzyme-linked Immunosorbent Assay (ELISA). The results obtained revealed viable fungal counts ranging from 3 x 10 2 to 3.2 x 10 3 cfu/g. The fungal contaminants identified from the samples include Aspergillus flavus, Aspergillus niger, and Aspergillus fumigatus. The aflatoxins detected from the samples were within the range of 0.3 to 0.6 part per billion (ppb) which is less than the maximum value (10ppb) recommended by regulatory agencies such as NAFDAC. This indicates that the level of aflatoxin in the samples has insignificant risks to consumers. However, the fungal contamination is an indication of high-level contamination of the cereals, the key producers of aflatoxins. The contamination of such products by fungi should be a source of worry and necessitates the need for proper personal and environmental hygiene in the processing of cereals.

JOURNAL OF ENVIRONMENTAL MICROBIOLOGY AND TOXICOLOGY, Jul 31, 2022

As a result of the fact that several research do not carry out statistical diagnostics on the non... more As a result of the fact that several research do not carry out statistical diagnostics on the nonlinear model that was employed, the data could not be random. Because these systems rely on random data, this is a necessity for all parametric statistical assessment procedures. The Wald-Wolfowitz runs test was done on the modified logistics that were employed in the fitting of the growth curve of immobilized Pseudomonas putida on phenol. This test was carried out in order to determine whether or not the logistical changes had any effect on the growth curve. This test was carried out so that it could be determined whether or not the adjustments made to the logistical processes were successful. The runs test showed that there was a total of eight runs, which contradicts the expectation that there would only be seven runs due to the unpredictability of the circumstance. The assumption was based on the fact that there would only be seven runs. Since the p-value was larger than 0.05, the null hypothesis is not rejected; this suggests that there is no convincing evidence of the non-randomness of the residuals; rather, the residuals represent noise in the data. As a consequence of the findings of Grubb's test, which indicate that there is no outlier, it is not necessary to reanalyze the data because the modified logistics model used in the fitting of the growth curve of immobilized Pseudomonas putida on phenol was adequate enough. This means that the reanalysis would be unnecessary.

International Journal of Current Microbiology and Applied Sciences, Apr 10, 2019

JOURNAL OF ENVIRONMENTAL MICROBIOLOGY AND TOXICOLOGY, Dec 31, 2020

Physical, chemical or biological data mathematical simulation may assist the investigator to desc... more Physical, chemical or biological data mathematical simulation may assist the investigator to describe a phenomenon found based on physical, chemical or biological mechanisms. The model may also be used to forecast or predict future behavior, simulate a hypothetical event or feedback, and better tests can be planned. Molybdenum reduction to the insoluble molybdenum blue by bacteria is an emerging tool for bioremediation of molybdenum pollutant worldwide. In this study, the molybdenum reduction rate by the bacterium Pantoea sp. strain HMY-P4 was studied for its inhibitory kinetics characteristics using sodium molybdate as a substrate. Modeling kinetics showed that molybdenum reduction could be explained by several models such as Monod, Haldane, Hans-Levenspiel, Luong, Teissier, Aiba and Yano with Aiba as the best model as judged using error function analysis such as bias and accuracy factors (BF and AF), root mean square error (RMSE), adjusted coefficient of determination (adjR 2), and corrected Akaike Information Criterion (AICc). The calculated values for the Aiba constants qmax (the maximum specific substrate degradation rate (h −1), Ks (concentration of substrate at the half maximal degradation rate (mg/L) or saturation constant and Ki (inhibition constant (mg/L)) were 0.060 (95% CI, 0.024 to 0.096), 0.302 (95% CI, 0.381 to 0.222) and 0.953 (95% CI, 0.568 to 1.338), respectively. These model parameters indicate a good tolerance of the bacterium against high concentration of toxic molybdenum making the bacterium useful for bioremediation works.

Bulletin of Environmental Science and Sustainable Management, Dec 31, 2022

Acrylamide pollution and contamination can come from a variety of sources and is an emerging toxi... more Acrylamide pollution and contamination can come from a variety of sources and is an emerging toxic pollutant that need remediation. A molybdenum-reducing bacteria that had been previously isolated and demonstrated the ability to degrade amides was further studied of its critical parameters contributing to optimum growth on acrylamide. The Box-Behnken design was utilized in optimizing the three previously identified significant components (pH, incubation time and acrylamide concentration). ANOVA, the pertubation's plot, and several other diagnostic plots were utilized in the analysis of the significant factors or parameters that contributed. The model was supported by the diagnostic plots including the half-normal, Cook's distance, leverage vs runs, residual vs runs, Box-Cox, DFFITS, and DFBETAS. Conditions that were predicted to be optimal were found and analyzed in order to find the optimal growth given the factors that were used and to determine the optimal concentration, which was 1 g/L. The solutions for finding the optimal growth predicted a growth maximum of 12.055 Log CFU/mL (95 percent confidence interval (C.I.) from 11.550 to 12.593), and verification using experimental results resulted in a growth of 12.908 Log CFU/mL (12.744 to 13.072) with the results being close to the predicted values but was significantly higher than the predicted data. The second numerical optimization was for predicting the highest acrylamide concentration tolerable for growth and the solution shows a predicted a growth maximum of 12.055 Log CFU/mL (95 percent confidence interval from 11.550 to 12.593). This solution was experimentally verified resulting in a growth of 12.195 Log CFU/mL (95 percent confidence interval from 11.806 to 12.584) with the actual results being in accordance with the predicted values. The results of the RSM exercise showed that growth on acrylamide may be optimized more effectively with RSM than with OFAT, which indicates that RSM is more useful than OFAT in this regard.

JOURNAL OF BIOCHEMISTRY, MICROBIOLOGY AND BIOTECHNOLOGY, Dec 31, 2022

The association between serum 25-Hydroxy vitamin D (25-OH vitamin D) levels in hypothyroid subjec... more The association between serum 25-Hydroxy vitamin D (25-OH vitamin D) levels in hypothyroid subjects with and without thyroid peroxidase (TPO) antibodies is controversial. There is increasing evidence that 25-OH vitamin D level is associated with autoimmune diseases. The analytical cross-sectional case-control and hospital-based study were conducted at Professor Al-Mahdi M. Ali Center for Diabetes and Endocrinology in Khartoum from February to October 2020. Sixty subjects with hypothyroidism were recruited from the follow-up clinic. Thirty age and sex-matched subjects were used as control. Thyroid Function Tests [Thyroid-stimulating hormone (TSH), Free Thyroxine (FT4), and Free triiodothyronine (FT3)] were measured using TOSOH AIA 360 system analyzer, and serum 25-OH vitamin D level was measured using semiautomatic I-Chroma-II reader and thyroid peroxidase antibodies (TPO antibodies) were measured in both cases and controls was estimated using ELISA. The results were analyzed using SPSS version 21. TSH was significantly increased in both TPO antibodies positive and TPO antibodies negative hypothyroid subjects than in the controls (22.3±4.44), (10.5±2.55) (3.42±0.75) with a P-value of 0.000. FT4 has decreased in both TPO antibodies positive and TPO antibodies negative subjects than in the control (0.51±0.21) (0.56±0.19) (2.0±0.55) with a Pvalue of 0.002. FT3 has significantly decreased in both TPO antibodies positive and TPO antibodies negative subjects than in the control (0.73±0.31)(0.73±0.49)(3.67±0.81) with a pvalue of 0.0001. 25-OH Vitamin D level was lower among hypothyroid subjects than in the control. Subjects with positive TPO antibodies had lower 25-OH vitamin D levels than the TPOantibody negative subjects compared to control (7.45±4.50 ̽) (10.5±7.18)(48.8±10.0) with Pvalue 0.000. Females 46(77%) were more than males 14(23%) and geographically most subjects were coming from the central part of Khartoum state.

BIOREMEDIATION SCIENCE AND TECHNOLOGY RESEARCH, Dec 31, 2020

Commiphora africana (A. Rich.) is a genus from the family of Burseraceae. The plant is known as "... more Commiphora africana (A. Rich.) is a genus from the family of Burseraceae. The plant is known as "dashi" in Hausa, "badadi" in Fulfude, and "kabi" in the Kanuri languages of Nigeria [1]. It is a bush or small tree found mainly in the tropical African savannah forest and dry areas [2]. Commiphora africana is a savannah. The shrub is around 4-6m long, but can often be too tall developing to between 12 and 15 metres. Most of the bark Commiphora africana is papery and peels free, Papery flakes, exposing a green bark underneath. This is the leaves are entirely made up. The Fruit of Commiphore africana greatly improves the identification of an individual. The species when the fruit is ripe, it splits into half showing this is a brightly colored pseudoaril. This fleshy little appendage in whole or in part, the seed as a part of a connection to part of the seed. The type Pseudo-aril varies from species to species [3]. Commiphora africana stem bark has been documented for the treatment of infected wounds, the root is typically chewed for the treatment of co inflammation, arthritis, obesity, microbial infection, wounds, pain, fractures, tumors and gastrointestinal diseases [5]. The selection of the best solvent for phytochemical extraction is important due to the presence of phytochemicals with various chemical structures and polarities that may affect their solubility in the chosen solvent. The optimal solution extraction will optimize the output of phytochemicals and antioxidants [2,6]. Water is commonly used in phytochemical mining with methanol, ethanol, acetone and a combination of these organic solvents with water [3]. The rise in solvent polarity between hexane and distillated water (hexane < ethnol < methanol < distilled water) further indicates that the solubility of phytochemical compounds is affected by solvent polarity.

JOURNAL OF ENVIRONMENTAL MICROBIOLOGY AND TOXICOLOGY, Dec 31, 2020

In the quest for novel bioactive metabolites, which can also be used as therapeutic agents, Adian... more In the quest for novel bioactive metabolites, which can also be used as therapeutic agents, Adiantum philippense (A. philippense), an ethnomedical important fern, has become a fascinating herb. In this study, the predictive mathematical modelling of A. philippense crude extract was tested against E. coli, a common food pathogen for its phytochemical constituents, antagonistic ability, and effect on bacterial adhesion and biofilm formation was calculated. For the first time in this paper we present various kinetics models such as von Bertalanffy, Baranyi-Roberts, modified Schnute, Modified Richards, Modified Gompertz, Modified Logistics and Huang were used to get values for the above kinetic constants or parameters. von Bertalanffy of the entire model was found to be the best model with the highest adjusted R 2 value with the lowest RMSE value. The accuracy and bias factors values were close to unity (1.0). The parameters obtained from Von Bertalanffy model for E. coli and chloramphenicol when compared with control values were the K 1.146 (95% C.I. 1.050-1.241) and 0.912 (95% C.I. 0.783-1.041), A 0.831 (95% C.I. 0.669-0.994) and 0.699 (95% C.I. 0.519-0.880) Km 1.146 (95% C.I. 0.746-1.546) and 1.210 (95% C.I. 0.478-1.942) respectively. This shows that A. philippense was active against E. coli.

JOURNAL OF ENVIRONMENTAL MICROBIOLOGY AND TOXICOLOGY, Dec 31, 2021

A predictive model was performed to describe Pseudomonas stutzeri strain DN2 growth behaviour in ... more A predictive model was performed to describe Pseudomonas stutzeri strain DN2 growth behaviour in tributyltin chloride, using primary Modelling and a polynomial model as a secondary predictive model. In this investigation, data predicted using the modified Logistic (ML) was the most accurate. The Bias Factor (Bf) and Accuracy Factor (Af) values for the (ML) model were 1.39 and 1.51, indicating that the predictions were within a reliable range. The low RMSE value of 0.14, R 2 and adj R 2 (0.99) value closer to 1, showing that modified logistics is better than the other models at describing the growth behaviour of Pseudomonas stutzeri strain DN2 in toxic tributyltin chloride. Both the Aiba and Haldane models on the other hand, among the secondary model best fit the behaviours having low RMSE and MSE values and adjR 2 value closer to 1. In this study, the primary and secondary kinetics of Pseudomonas stutzeri strain DN2 growth behaviour in tributyltin chloride was explored and it was shown in this study that the modified logistic and the Haldane models better suit the growth behavior of Pseudomonas stutzeri strain DN2 in tributyltin chloride. The parameters obtained from the modelling exercise will be very valuable in transferring the laboratory results to the field.

BIOREMEDIATION SCIENCE AND TECHNOLOGY RESEARCH, Dec 31, 2022

Mycotoxins are harmful secondary metabolites generated by a variety of fungi, and they may be fou... more Mycotoxins are harmful secondary metabolites generated by a variety of fungi, and they may be found in a vast array of food and feed commodities and processed meats from animals fed infected meal. Numerous mycotoxins are extremely resistant and survive food processing, entering the food chain and posing a concern to human health. The "optical waveguide lightmode spectroscopy" (OWLS) method was used to detect aflatoxin B1 in plant sample matrices. The calibration curve for the detection of aflatoxin B1 utilizing "optical waveguide lightmode spectroscopy" (OWLS) displayed a sigmoidal shape; hence, the 5-PL or 4-PL model should be used to fit the data rather than a linear model. Using error function analysis with functions such as AICc, HQC, BIC, RMSE, adjR 2 , Bias Factor, and Accuracy Factor, the 5-PL and 4-Pl models are distinguished inconsistently. The overlapping confidence intervals of the LogEC50 values suggested that the two techniques did not differ much, and the 4-PL model was selected due to its smaller number of parameters. The Limits of Detection for aflatoxin B1 value based on the 4-PL equation was 8.787 ng/mL with the 95% confidence interval from 5.728 to 13.100. In this study, the use of the 4-PL model was successful and was able to represent the entire date curve, not only the linear section. The linear component is crucial as a handy and swift approach for assessing the sensitivity of a developed biosensor technology and is often a more beneficial method for field applications when a quick and straightforward evaluation is required.

Bulletin of Environmental Science and Sustainable Management, Dec 31, 2022

In the long run, bioremediation is the utmost cost-effective way, particularly at low concentrati... more In the long run, bioremediation is the utmost cost-effective way, particularly at low concentrations while other methods like physical or chemical procedures would be ineffective, for the elimination of heavy metals and organic pollutants. The process of reducing molybdenum (sodium molybdate) with an oxidation state of (VI) to molybdenum blue (oxidation state from V to VI) serves as a form of detoxification. Important characteristics, such as specific reduction rate, theoretical reduction maximum, and the lag duration of reduction, can be shown by mathematical modeling of the reduction process. While natural logarithm transformation is a common linearization approach, it is not precise and can only provide a rough estimate of the most important single measurable parameter; the specific growth rate. In this study, for the first time, values for the aforementioned parameters or constants were calculated using a wide range of models, including the logistic, Gompertz, Richards, Schnute, Baranyi-Roberts, Buchanan three-phase, von Bertalanffy and most recently, the Huang model. Based on statistical tests including root-mean-square error (RMSE), bias factor (BF), adjusted coefficient of determination (adjR 2), accuracy factor (AF), and corrected Akaike information criterion (AICc), the logistics model was found to be the best model for representing the Mo-blue production curve of Bacillus sp. strain khayat. The fitting technique resulted in the calculation of three parameters: specific reduction rate (h-1), Lag period (h), and maximum Mo-blue production (nmole Mo-blue). In this study, we utilize a mathematical technique to determine the reduction parameters for Mo-blue production from sodium molybdate. The calculated parameter constants will be used to create secondary models, such as the influence of substrate and environment on Mo-blue synthesis.

Bulletin of Environmental Science and Sustainable Management, Jul 31, 2022

In this study, we use the Wald-Wolfowitz runs test as a statistical diagnosis tool to check wheth... more In this study, we use the Wald-Wolfowitz runs test as a statistical diagnosis tool to check whether the randomness of the residual for the Morgan-Mercer-Flodin (MMF) utilized in the fitting of the prediction of cumulative death cases in Nigeria owing to COVID-19. The runs test revealed that there were 13 total runs, however the number of runs that should have been expected based on the randomization assumption was 26. Because the p-value was less than 0.05, we can conclude that the residuals are not truly random and must reject the null hypothesis. Too many instances of a specific run sign may indicate the presence of a negative serial correlation; on the other hand, too few runs may indicate the presence of a clustering of residuals with the same sign or the presence of a systematic bias. A further analysis of the residuals using the Grubb's test indicate the existence of an outlier, which indicates that the data must be remodeled because of the presence of the outlier.

Bayero Journal of Pure and Applied Sciences, May 9, 2018

The effects of methanol, ethanol root extract of Calotropis procera (MRECP, ERECP) and livolin on... more The effects of methanol, ethanol root extract of Calotropis procera (MRECP, ERECP) and livolin on liver function indices of CCl 4 induced hepatotoxicity rats model was evaluated. Fifty (50) albino rats were grouped into Five (I, II, III, IV and V) of 10 rats each, 120mg/kg body weight CCl with olive oil in the ratio 1:1 was administered to rats in groups II, III, IV and V intramuscularly followed by oral administration of 10mg/kg livolin, 10mg/kg methanol and ethanol root extract of C. Procera to group III, IV and V respectively. G respectively. Analysis of variance (ANOVA) for multiple comparison test were used to compare the indices of the liver and kidney functions for the test and control group at 10 days interval for 20 days. The hepatic biochemical markers Alanine Amino Transferase (ALT), Aspartate Amino Transferase (AST), Alkaline Phosphatases (ALP) of group Gp II were significantly higher (P<0.001) compared to others except GpI, while group III (treated with livolin) was stati (P<0.05) when compared with control (Gp I), this confirms the toxicity and treatment with livolin respectively. Oral administrations of the MRECP lowered all the liver function markers and increased the concentration of urea and albumin MRECP may reverse the chemically induced tissue damage; in contrast, ERECP produced toxicity at both exposures as evidenced from the histopathology of the liver hepatocytes. The histopathological analysis of MERCP indicates improved fine architecture of the liver and kidney cells which are comparable to livolin treated group. In conclusion, the overall results suggest that ethanol root extracts of C. Procera may have moderate hepatorenal compared to methanol extracts. Keywords; Calotropis Procera, Hepatocurative, antihepatotoxic, hepatotoxicity and ethanol) extract of C. Procera root in this study. Calotropis procera belongs to the family Asclepiacea (milkweed family) of the Genus Calotropis R. Br. (Calotropis). Calotropisprocera or Giant milkweed is also known as sodom apple, calotrope, French cotton,

Bulletin of Environmental Science and Sustainable Management, Dec 31, 2021

The well function of aquatic and soil organisms including terrestrial, as well as those of all ot... more The well function of aquatic and soil organisms including terrestrial, as well as those of all other living things, can be jeopardized if dyes aren't properly treated, as their degradation might lead to carcinogenic chemicals. Complete mineralization of dye is the only option, and this can be done using microorganisms. The azo blue dye inhibitory effect to its biodegradation by Streptomyces DJP15 was modelled using several inhibition kinetic models such as Haldane, Monod, Luong, Aiba, Teissier-Edwards, Han-Levenspiel and Yano. The result shows that only the Luong model failed to fit the data. The rest of the models visually ft the data although data fitting is problematic with datapoints of less than 10, which the result in this work demonstrates where it is not easy to choose the best model where nearly all of the models fit the data in a similar manner. Resorting to statistical discriminatory function, the best model was Monod with the smallest RMSE and AICc values and the highest adjR 2 values and values for AF and BF close to unity. However, Monod has only two parameters and is the most robust. The Monod's parameters were maximum specific degradation rate of 0.431 (1/h) (95% confidence interval from 0.391 to 0.456) and concentration of substrate giving half maximal rate or Ks value of 0.0001 (mg/L) (95% C.I. from-0.01 to 12.12). The confidence interval value for the Ks value was very large indicating poor data quality. This should be an important consideration in future works where the data point number can be increased to improve model fitting exercise.

Acrylamide; a neurotoxicant, is an emerging pollutant of global importance. As a strategy for bio... more Acrylamide; a neurotoxicant, is an emerging pollutant of global importance. As a strategy for bioremediation, the breakdown of acrylamide by the action of microbes has seen a gradual but consistent increase in attention all over the world. An acrylamide-degrading bacterium tentatively identified as Bacillus sp. strain UPM2021n was screened for significant parameters contributing to optimized growth on acrylamide using a two-level factorial design. The two-level factorial design was adopted in screening of five independent factors influencing the growth of the bacterium on acrylamide. These factors include pH, temperature, incubation time, acrylamide concentration and glucose concentration. A total of 32 experiments with three replications of the centre points were carried out. The two-level factorial design was successful in finding important contributing parameters in the growth of this bacterium on acrylamide, which were pH and incubation time (p<0.05) that can be further optimized using RSM in future works. The important contributing factors or parameters were analysed using ANOVA, Pareto's chart and pertubation's plot and other diagnostic plots. The diagnostic plots such as half-normal, Cook's distance, residual vs runs, leverage vs runs, Box-Cox, DFFITS, DFBETAS all supported the two-level factorial conclusion with the exception of potentially two outliers that meant the experiment should either be repeated again using blocks or the potential outliers removed from analysis. This significant factors in this study are well within the range reported in many acrylamide-degrading microorganisms. The significant factors obtained in this study will be further processed using Response Surface Method (RSM).

BIOREMEDIATION SCIENCE AND TECHNOLOGY RESEARCH, Dec 31, 2022

In ruminants, even trace amounts of molybdenum can be lethal. In areas with high pollution, molyb... more In ruminants, even trace amounts of molybdenum can be lethal. In areas with high pollution, molybdenum levels in soil and mine tailings can exceed 20,000 ppm. Bioremediation of molybdenum can be challenging when toxic copper is also present. This research presents a novel approach using dialysis tubing and the molybdenum-reducing activity of Bacillus sp. strain Neni-8 for molybdenum removal from aqueous solutions. Molybdenum blue (Mo-blue), produced during enzymatic reduction, is insoluble in dialysis tubing and this can be a twofold advantage as a method of removal and as a method to protect bacterial cells from heavy metal inhibition, especially copper. In this experiment, we assess the toxicity-shielding effect of dialysis tubing for molybdenum reduction to Mo-blue by this bacterium in the presence of copper. As the concentrations of copper were increased, both free and immobilized cells were strongly inhibited. Modelling using the dissociation−one-phase exponential decay model gave an IC50 value for the immobilized form of 0.1107 mg/L (95% confidence interval from 0.073 to 0.217 while the IC50 value for the free cell system was 0.023 mg/L (95% C.I. from 0.019 to 0.028). Since the confidence interval for the IC50 values did not overlap, the immobilized system gave better protection from copper than the free cell system. Toxicity to free cells was higher than toxicity to cells trapped in dialysis tubes, suggesting that trapping Mo-reducing cells may be an effective strategy for the bioremediation of water or wastewater contaminated with multiple heavy metals.