Jonathan Maiangwa - Academia.edu (original) (raw)

Papers by Jonathan Maiangwa

Applied Microbiology and Biotechnology

Science World Journal, 2020

The routine preservation of microorganisms promotes a complete depression of cell viability, stab... more The routine preservation of microorganisms promotes a complete depression of cell viability, stability and metabolic activity. In this study, Saccharomyces uvarum preserved under various conditions, was successfully reactivated within a relatively short time. The oils selected for preservation demonstrated higher cell viability and survival of yeast cells at cell count per mL of 2×106 cfu/mL Yeast cells preserved in 15 % glycerol in liquid-nitrogen all showed good survival rates and reactivation with 11 × 106 cfu/mL after 2 months. Saccharomyces uvarum was pitched in sorghum wort of two varieties (white & red) and fermentation was allowed to proceed. Results showed that protesse production was higher in red sorghum with yeast preserved in olive oil, mineral oil and corn oil. Production was optimal with isolate preserved under mineral oil and corn oil for 2, 4, 6 and 8 days during fermentation of white sorghum. The highest ethanol content of 27.8 % to 26.1 % was recorded with isolate...

African Journal of Microbiology Research, 2016

Journal of Molecular Graphics and Modelling, 2021

Critical to the applications of proteins in non-aqueous enzymatic processes is their structural d... more Critical to the applications of proteins in non-aqueous enzymatic processes is their structural dynamics in relation to solvent polarity. A pool of mutants derived from Geobacillus zalihae T1 lipase was screened in organic solvents (methanol, ethanol, propanol, butanol and pentanol) resulting in the selection of six mutants at initial screening (A83D/K251E, R21C, G35D/S195 N, K84R/R103C/M121I/T272 M and R106H/G327S). Site-directed mutagenesis further yielded quadruple mutants A83D/M121I/K251E/G327S and A83D/M121I/S195 N/T272 M, both of which had improved activity after incubation in methanol. The km and kcat values of these mutants vary marginally with the wild-type enzyme in the methanol/substrate mixture. Thermally induced unfolding of mutants was accompanied with some loss of secondary structure content. The root mean square deviations (RMSD) and B-factors revealed that changes in the structural organization are intertwined with an interplay of the protein backbone with organic solvents. Spatially exposed charged residues showed correlations between the solvation dynamics of the methanol solvent and the hydrophobicity of the residues. The short distances of the radial distribution function provided the required distances for hydrogen bond formation and hydrophobic interactions. These dynamic changes demonstrate newly formed structural interactions could be targeted and incorporated experimentally on the basis of solvent mobility and mutant residues.

PeerJ, 2017

Extremophiles, 2014

Psychrophilic microorganisms are cold-adapted with distinct properties from other thermal classes... more Psychrophilic microorganisms are cold-adapted with distinct properties from other thermal classes thriving in cold conditions in large areas of the earth&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s cold environment. Maintenance of functional membranes, evolving cold-adapted enzymes and synthesizing a range of structural features are basic adaptive strategies of psychrophiles. Among the cold-evolved enzymes are the cold-active lipases, a group of microbial lipases with inherent stability-activity-flexibility property that have engaged the interest of researchers over the years. Current knowledge regarding these cold-evolved enzymes in psychrophilic bacteria proves a display of high catalytic efficiency with low thermal stability, which is a differentiating feature with that of their mesophilic and thermophilic counterparts. Improvement strategies of their adaptive structural features have significantly benefited the enzyme industry. Based on their homogeneity and purity, molecular characterizations of these enzymes have been successful and their properties make them unique biocatalysts for various industrial and biotechnological applications. Although, strong association of lipopolysaccharides from Antarctic microorganisms with lipid hydrolases pose a challenge in their purification, heterologous expression of the cold-adapted lipases with affinity tags simplifies purification with higher yield. The review discusses these cold-evolved lipases from bacteria and their peculiar properties, in addition to their potential biotechnological and industrial applications.

Pakistan Journal of Nutrition, 2013

2 Abstract: Eight microbial yeast and lactobacillus isolates were identified during spontaneous f... more 2 Abstract: Eight microbial yeast and lactobacillus isolates were identified during spontaneous fermentation of mixed cereal gruels (rice, maize and millet) for 78 h at room temperature. The potential of these isolates to act as single starter was further studied in a fermentation set up for Masa (waina) production. The resulting batter from the milled rice used was inoculated with 2.0 x 10 cfu/ml of Saccharomyces and Lactobacillus 6 inoculum suspension in different set up. The fermented gruel was sized and fried in little oil to produce Masa (Waina). The Masa was analyzed for physical (thickness, volume and spread) and nutritional qualities through an untrained panelist. The dimension of the Masa ranges from 4.50-6.0cm in diameter, 1.5-2.0cm thickness and 50-68g in weight. The result of the proximate analysis showed that for both isolates there was a steady increase of crude fibre ranging from 0.75-1.04%, crude protein for all isolates gave insignificant difference in amount ranging between 7.33 and 8.63% for Saccharomyces and Lactobacillus spp., respectively. There was reduction in fat between isolates with Lactobacillus having the lowest fat value of 12.06%. There was increase in moisture content ranging from 35.5-42.13% for Saccharomyces and Lactobacillus spp., respectively. There was high production of carbohydrate, whereas there was no significant difference in terms of results obtained between the isolates and baker's yeast used as control in this study. The sensory evaluation showed that all samples of Masa produced were preferred by th e panelist.

Lipases are one of nature`s most endowed group of proteins when considering their broad functiona... more Lipases are one of nature`s most endowed group of proteins when considering their broad functional biotechnological and industrial relevance. The fundamental and technological conditions requirements for enzymes hampers the application of lipases as biocatalysts. Central to these challenges are the space and time in prospecting for natural enzymes with biocatalytic properties. In this respect, naturally obtained lipases are engineered and designed into biocatalysts that can efficiently be used. Inspired by the proven thermostability and diminished solvent stability of a lipase from Geobacillus zalihae, this dissertation addresses the impediment of solvent stability by way of directed evolutionary construction of mutant variants capable of maintaining important structural elements, protein folding and stability in high concentrations of organic solvents. Firstly, the behavior of T1 lipase was investigated in hydrophilic chain length organic solvents by molecular dynamic simulations. ...

Applied Microbiology and Biotechnology

Molecules (Basel, Switzerland), Jan 7, 2018

Most available methods for the preservation of microorganisms provide vast possibilities of maint... more Most available methods for the preservation of microorganisms provide vast possibilities of maintaining their intensive cell viability, stability and metabolic performance. However, certain conditionsresult in losses of essential properties and changes in physiological and growth activity. In this study, Saccharomyces uvarum preserved under various conditions was successfully reactivated within a relatively short time,indicating that viability, stability and ability to grow were not affected by the storage conditions. The oils selected for preservation 6 demonstrated higher cell viability and survival of yeast cellswith no significant difference of the cell count per mL at over 2×10 cfu/mL. Yeast 6 cells preserved in 15 % glycerol in liquid-nitrogen all showed good survival rates and reactivation with 11 × 10 cfu/mL after 2 months. 6 Saccharomyces uvarum was pitched in sorghum wort of two varieties (white & red) at a pitching rate of 2.2 × 10 cfu/ml and fermentation was allowed to proceed.Results showed that amylase production was higher in red sorghum when compared with that produce in white sorghum. Production was optimal with isolate preserved under mineral oil and castor oil for 2, 4, 6 and 8 days. There was sgnifcant difference observed between the room temprtaure and refrigeration temperature of preservation on amylase production for both sorghum varieties. The highest ethanol content of 27.8% to 26.1%was recorded with isolate preserved in mineral oil at room tempertaure for the white sorghum variety, with olive oil having the least yield of 15 %.The results showed that the maximum yield in both wort varieties was generated in the red sorghum wort fermented with yeast preserved in all oils at room temperature. The overall trend was that there was better ethanol yield, cell viability and amylase activity with yeast cells preserved at room temperature with mineral oil giving the best output. Therefore, the use of some alternative methods for yeast culture preservation (mineral oil and corn oil) may be proposed particularly for short-term storage of yeast cells rather than the routine subcultring. More so, liquid nitrogen is remarkably still considered the best condition of keeping yeast for a very long time.

Journal of Molecular Graphics and Modelling, 2021

Critical to the applications of proteins in non-aqueous enzymatic processes is their structural d... more Critical to the applications of proteins in non-aqueous enzymatic processes is their structural dynamics in relation to solvent polarity. A pool of mutants derived from Geobacillus zalihae T1 lipase was screened in organic solvents (methanol, ethanol, propanol, butanol and pentanol) resulting in the selection of six mutants at initial screening (A83D/K251E, R21C, G35D/S195 N, K84R/R103C/M121I/T272 M and R106H/ G327S). Site-directed mutagenesis further yielded quadruple mutants A83D/M121I/K251E/G327S and A83D/M121I/S195 N/T272 M, both of which had improved activity after incubation in methanol. The k m and k cat values of these mutants vary marginally with the wild-type enzyme in the methanol/substrate mixture. Thermally induced unfolding of mutants was accompanied with some loss of secondary structure content. The root mean square deviations (RMSD) and B-factors revealed that changes in the structural organization are intertwined with an interplay of the protein backbone with organic solvents. Spatially exposed charged residues showed correlations between the solvation dynamics of the methanol solvent and the hydrophobicity of the residues. The short distances of the radial distribution function provided the required distances for hydrogen bond formation and hydrophobic interactions. These dynamic changes demonstrate newly formed structural interactions could be targeted and incorporated experimentally on the basis of solvent mobility and mutant residues.

The variety of halogenated substances and their derivatives widely used as pesticides, herbicides... more The variety of halogenated substances and their derivatives widely used as pesticides, herbicides and other industrial products is of great concern due to the hazardous nature of these compounds owing to their toxicity, and persistent environmental pollution. Therefore, from the viewpoint of environmental technology, the need for environmentally relevant enzymes involved in biodegradation of these pollutants has received a great boost. One result of this great deal of attention has been the identification of environmentally relevant bacteria that produce hydrolytic dehalogenases—key enzymes which are considered cost-effective and eco-friendly in the removal and detoxification of these pollutants. These group of enzymes catalyzing the cleavage of the carbon-halogen bond of organohalogen compounds have potential applications in the chemical industry and bioremediation. The dehalogenases make use of fundamentally different strategies with a common mechanism to cleave carbon-halogen bonds whereby, an active-site carboxylate group attacks the substrate C atom bound to the halogen atom to form an ester intermediate and a halide ion with subsequent hydrolysis of the intermediate. Structurally, these dehalogenases have been characterized and shown to use substitution mechanisms that proceed via a covalent aspartyl intermediate. More so, the widest dehalogenation spectrum of electron acceptors tested with bacterial strains which could dehalogenate recalcitrant organohalides has further proven the versatility of bacterial dehalogenators to be considered when determining the fate of halogenated organics at contaminated sites. In this review, the general features of most widely studied bacterial dehalogenases, their structural properties, basis of the degradation of organohalides and their derivatives and how they have been improved for various applications is discussed.

The dynamics and conformational landscape of proteins in organic solvents are events of potential... more The dynamics and conformational landscape of proteins in organic solvents are events of potential interest in nonaqueous process catalysis. Conformational changes, folding transitions, and stability often correspond to structural rearrangements that alter contacts between solvent molecules and amino acid residues. However, in nonaqueous enzymology, organic solvents limit stability and further application of proteins. In the present study, molecular dynamics (MD) of a thermostable Geobacillus zalihae T1 lipase was performed in different chain length polar organic solvents (methanol, ethanol, propanol, butanol, and pentanol) and water mixture systems to a concentration of 50%. On the basis of the MD results, the structural deviations of the backbone atoms elucidated the dynamic effects of water/organic solvent mixtures on the equilibrium state of the protein simulations in decreasing solvent polarity. The results show that the solvent mixture gives rise to deviations in enzyme structure from the native one simulated in water. The drop in the flexibility in H 2 O, MtOH, EtOH and PrOH simulation mixtures shows that greater motions of residues were influenced in BtOH and PtOH simulation mixtures. Comparing the root mean square fluctuations value with the accessible solvent area (SASA) for every residue showed an almost correspondingly high SASA value of residues to high flexibility and low SASA value to low flexibility. The study further revealed that the organic solvents influenced the formation of more hydrogen bonds in MtOH, EtOH and PrOH and thus, it is assumed that increased intraprotein hydrogen bonding is ultimately correlated to the stability of the protein. However, the solvent accessibility analysis showed that in all solvent systems, hydrophobic residues were exposed and polar residues tended to be buried away from the solvent. Distance variation of the tetrahedral intermediate packing of the active pocket was not conserved in organic solvent systems, which could lead to weaknesses in the catalytic H-bond network and most likely a drop in catalytic activity. The conformational variation of the lid domain caused by the How to cite this article Maiangwa et al. (2017), Lid opening and conformational stability of T1 Lipase is mediated by increasing chain length polar solvents. PeerJ 5:e3341; DOI 10.7717/peerj.3341

Otitis media (OM) is a multifactorial disease characterized by high rate of recurrence in young c... more Otitis media (OM) is a multifactorial disease characterized by high rate of recurrence in young children and considered to cause hearing impairment in children. This study was undertaken to evaluate the antibacterial sensitivity of Gram-negative bacteria of OM to some antibiotics. A total of Fifty four (54) samples were obtained from patients with suspected cases of otitis media coming into the National Ear Care Centre for the first time. Fifty four (54) patients (29 male, 25 female), with mean ages of 3.86 and 3.29 respectively, tested positive to OM pathogens with a total of 84 bacterial isolates while no culturable pathogen was observed in 4 patients (7.4%). The study reveals highest frequency of Pseudomonas aeruginosa 60 (71.43 %) followed by Proteus mirabilis 14 (16.67), Klebsiella pnuemoniae 6 (7.14) and Escherichia coli 4 (4.76). P. aeruginosa had the highest prevalence among patients < 30 years, whereas K. pnuemoniae and E. coli had the least isolated across all age groups. Antimicrobial susceptibility test showed highest frequency of resistance among all isolates to amoxicillin, cotrimoxazole, nitrofurantoin and nalidixic acid. However, gentamicin, ofloxacin, augmentin and tetracycline were effective against Pseudomonas aeruginosa but ineffective against other isolates. Although antibiotics are the most preferred and prescribed drugs in incidents of OM, it is clear from this study that antimicrobial resistance still remains a persistent among bacterial pathogens of otitis media.

Psychrophilic microorganisms are cold-adapted with distinct properties from other thermal classes... more Psychrophilic microorganisms are cold-adapted
with distinct properties from other thermal classes thriving
in cold conditions in large areas of the earth’s cold
environment. Maintenance of functional membranes,
evolving cold-adapted enzymes and synthesizing a range
of structural features are basic adaptive strategies of psychrophiles.
Among the cold-evolved enzymes are the coldactive
lipases, a group of microbial lipases with inherent
stability–activity–flexibility property that have engaged the
interest of researchers over the years. Current knowledge
regarding these cold-evolved enzymes in psychrophilic
bacteria proves a display of high catalytic efficiency with
low thermal stability, which is a differentiating feature with
that of their mesophilic and thermophilic counterparts.
Improvement strategies of their adaptive structural features
have significantly benefited the enzyme industry. Based on
their homogeneity and purity, molecular characterizationsof these enzymes have been successful and their properties
make them unique biocatalysts for various industrial and
biotechnological applications. Although, strong association
of lipopolysaccharides from Antarctic microorganisms
with lipid hydrolases pose a challenge in their purification,
heterologous expression of the cold-adapted lipases with
affinity tags simplifies purification with higher yield. The
review discusses these cold-evolved lipases from bacteria
and their peculiar properties, in addition to their potential
biotechnological and industrial applications.

Eight microbial yeast and lactobacillus isolates were identified during spontaneous fermentation ... more Eight microbial yeast and lactobacillus isolates were identified during spontaneous fermentation of mixed cereal gruels (rice, maize and millet) for 78 h at room temperature. The potential of these isolates to act as single starter was further studied in a fermentation set up for Masa (waina) production. The resulting batter from the milled rice used was inoculated with 2.0 x 10 cfu/ml of Saccharomyces and Lactobacillus 6 inoculum suspension in different set up. The fermented gruel was sized and fried in little oil to produce Masa (Waina). The Masa was analyzed for physical (thickness, volume and spread) and nutritional qualities through an untrained panelist. The dimension of the Masa ranges from 4.50-6.0cm in diameter, 1.5-2.0cm thickness and 50-68g in weight. The result of the proximate analysis showed that for both isolates there was a steady increase of crude fibre ranging from 0.75-1.04%, crude protein for all isolates gave insignificant difference in amount ranging between 7.33 and 8.63% for Saccharomyces and Lactobacillus spp., respectively. There was reduction in fat between isolates with Lactobacillus having the lowest fat value of 12.06%. There was increase in moisture content ranging from 35.5-42.13% for Saccharomyces and Lactobacillus spp., respectively. There was high production of carbohydrate, whereas there was n o significant difference in terms of results obtained between the isolates and baker's yeast used as control in this study. The sensory evaluation showed that all samples of Masa produced were preferred by the panelist.

Applied Microbiology and Biotechnology

Science World Journal, 2020

African Journal of Microbiology Research, 2016

Journal of Molecular Graphics and Modelling, 2021

PeerJ, 2017

Extremophiles, 2014

Pakistan Journal of Nutrition, 2013

Applied Microbiology and Biotechnology

Molecules (Basel, Switzerland), Jan 7, 2018

Journal of Molecular Graphics and Modelling, 2021

Critical to the applications of proteins in non-aqueous enzymatic processes is their structural d... more Critical to the applications of proteins in non-aqueous enzymatic processes is their structural dynamics in relation to solvent polarity. A pool of mutants derived from Geobacillus zalihae T1 lipase was screened in organic solvents (methanol, ethanol, propanol, butanol and pentanol) resulting in the selection of six mutants at initial screening (A83D/K251E, R21C, G35D/S195 N, K84R/R103C/M121I/T272 M and R106H/ G327S). Site-directed mutagenesis further yielded quadruple mutants A83D/M121I/K251E/G327S and A83D/M121I/S195 N/T272 M, both of which had improved activity after incubation in methanol. The k m and k cat values of these mutants vary marginally with the wild-type enzyme in the methanol/substrate mixture. Thermally induced unfolding of mutants was accompanied with some loss of secondary structure content. The root mean square deviations (RMSD) and B-factors revealed that changes in the structural organization are intertwined with an interplay of the protein backbone with organic solvents. Spatially exposed charged residues showed correlations between the solvation dynamics of the methanol solvent and the hydrophobicity of the residues. The short distances of the radial distribution function provided the required distances for hydrogen bond formation and hydrophobic interactions. These dynamic changes demonstrate newly formed structural interactions could be targeted and incorporated experimentally on the basis of solvent mobility and mutant residues.

Psychrophilic microorganisms are cold-adapted with distinct properties from other thermal classes... more Psychrophilic microorganisms are cold-adapted
with distinct properties from other thermal classes thriving
in cold conditions in large areas of the earth’s cold
environment. Maintenance of functional membranes,
evolving cold-adapted enzymes and synthesizing a range
of structural features are basic adaptive strategies of psychrophiles.
Among the cold-evolved enzymes are the coldactive
lipases, a group of microbial lipases with inherent
stability–activity–flexibility property that have engaged the
interest of researchers over the years. Current knowledge
regarding these cold-evolved enzymes in psychrophilic
bacteria proves a display of high catalytic efficiency with
low thermal stability, which is a differentiating feature with
that of their mesophilic and thermophilic counterparts.
Improvement strategies of their adaptive structural features
have significantly benefited the enzyme industry. Based on
their homogeneity and purity, molecular characterizationsof these enzymes have been successful and their properties
make them unique biocatalysts for various industrial and
biotechnological applications. Although, strong association
of lipopolysaccharides from Antarctic microorganisms
with lipid hydrolases pose a challenge in their purification,
heterologous expression of the cold-adapted lipases with
affinity tags simplifies purification with higher yield. The
review discusses these cold-evolved lipases from bacteria
and their peculiar properties, in addition to their potential
biotechnological and industrial applications.