Effect of Traditional Process Methods on the Physicochemical and Functional Properties of a Traditional Food Salt (Nikkih) Obtained from Waste Biomass Peels of Musa paradisiaca and Musa acuminate

In Cameroon, agrofood waste biomass such as peels of Musa paradisiaca and Musa acuminate is being valorized using various traditional processing methods to produce a traditional functional food salt, potash, locally called nikkih. Nikkih has been reported to have varying physicochemical and functional properties, which negatively affect the quality and stability of food prepared using it. This work aims at evaluating the effect of traditional process methods on the physicochemical and functional properties of nikkih produced from these peels in view of the optimization of the process. The peels were preprocessed using two methods: boiling at 90oC before drying and direct drying of raw samples. All samples were dried and combusted to ash at varying temperatures of 250oC, 300o C, and 350oC and times of 30 min, 60 min, and 90 min. The ash obtained was dissolved in varied volumes of water, filtered to obtain the nikkih. Yellow achu soup was prepared through the dry gum method using water and read palm oil, with nikkih as emulsifier. The physicochemical and functional properties of nikkih on yellow achu soup were evaluated using standard methods. The ash yield ranged from 10.62 ± 0.12% to 7.10 ± 0.05%, with the raw samples combusted at 3000C and 2500C having the highest and lowest values respectively. The pH of nikkih ranged from 10.95 ± 0 to 12.01 ± 0.056 while potash content ranged from 32.45 ± 0.905% to 72.29 ± 1.31%, with the highest and lowest values obtained from the raw sample combusted at 2500C and the boiled samples combusted at 3500C respectively. Alkaline content ranged from 61.7 ± 0.141% to 52.8 ± 0.141%, with boiled M. acuminate combusted at 3500C having the highest value and the lowest from raw M. paradisiaca combusted at 2500C. The foaming capacity and foam stability ranged from 6.9 ± 0.01% to 16.07 ± 2.51% and from 3.20 ± 0.07% to 11.205 ± 2.39% for M. acuminate and M. paradisiaca respectively. The emulsification index ranged from 85.62 ± 0.09% to 86.67 ± 1.141% after 24 hrs and from 26.0 ± 0.94% to 27.02 ± 2.390% after 48 hrs, with the highest value from the raw M. acuminate combusted at 350oC and the lowest from that combusted at 3000C. The potash source, pretreatment method, combustion conditions, and dilution factors all had an effect on the physicochemical and functional properties of nikkih.

Functional and Structural Characterization of Pediococcus pentosaceus-Derived Biosurfactant and Its Biomedical Potential against Bacterial Adhesion, Quorum Sensing, and Biofilm Formation

Biosurfactants are surface-active molecules of microbial origin and alternatives to synthetic surfactants with various applications. Due to their environmental-friendliness, biocompatibility, biodegradability, effectiveness to work under various environmental conditions, and non-toxic nature, they have been recently recognized as potential agents with therapeutic and commercial importance. The biosurfactant produced by various probiotic lactic acid bacteria (LAB) has enormous applications in different fields. Thus, in vitro assessment of biofilm development prevention or disruption by natural biosurfactants derived from probiotic LAB is a plausible approach that can lead to the discovery of novel antimicrobials. Primarily, this study aims to isolate, screen, and characterize the functional and biomedical potential of biosurfactant synthesized by probiotic LAB Pediococcus pentosaceus (P. pentosaceus). Characterization consists of the assessment of critical micelle concentration (CMC), reduction in surface tension, and emulsification index (% EI24). Evaluation of antibacterial, antibiofilm, anti-QS, and anti-adhesive activities of cell-bound biosurfactants were carried out against different human pathogenic bacteria (B. subtilis, P. aeruginosa, S. aureus, and E. coli). Moreover, bacterial cell damage, viability of cells within the biofilm, and exopolysaccharide (EPS) production were also evaluated. As a result, P. pentosaceus was found to produce 4.75 ± 0.17 g/L biosurfactant, which displayed a CMC of 2.4 ± 0.68 g/L and reduced the surface tension from 71.11 ± 1.12 mN/m to 38.18 ± 0.58 mN/m. P. pentosaceus cells bound to the crude biosurfactant were found to be effective against all tested bacterial pathogens. It exhibited an anti-adhesion ability and impeded the architecture of the biofilm matrix by affecting the viability and integrity of bacterial cells within biofilms and reducing the total EPS content. Furthermore, the crude biosurfactant derived from P. pentosaceus was structurally characterized as a lipoprotein by GC-MS analysis, which confirms the presence of lipids and proteins. Thus, our findings represent the potent anti-adhesion and antibiofilm potential of P. pentosaceus crude biosurfactant for the first time, which may be explored further as an alternative to antibiotics or chemically synthesized toxic antibiofilm agents.

Production optimization, stability and oil emulsifying potential of biosurfactants from selected bacteria isolated from oil-contaminated sites

Oil pollution is of increasing concern for environmental safety and the use of microbial surfactants in oil remediation has become inevitable for their efficacy and ecofriendly nature. In this work, biosurfactants of bacteria isolated from oil-contaminated soil have been characterized. Four potent biosurfactant-producing strains (SD4, SD11, SD12 and SD13) were selected from 27 isolates based on drop collapse assay and emulsification index, and identified as species belonging to Bacillus , Burkholderia , Providencia and Klebsiella , revealed from their 16S rRNA gene-based analysis. Detailed morphological and biochemical characteristics of each selected isolate were determined. Their growth conditions for maximum biosurfactant production were optimized and found quite similar among the four isolates with a pH of 3.0 and temperature 37°C after 6 or 7 days of growth on kerosene. The biosurfactants of SD4, SD11 and SD12 appeared to be glycolipids and that of SD13 a lipopeptide. Emulsification activity of most of the biosurfactants was stable at low and high temperatures (4–100°C), a wide range of pH (2–10) and salt concentrations (2–7% NaCl). Each biosurfactant showed antimicrobial activity against two or more pathogenic bacteria. The biosurfactants were well-capable of emulsifying kerosene, diesel and soya bean, and could efficiently degrade diesel.

Oily sludge degrading potentials of single and consortium of autochthonous bacterial species

Oily sludge (OS) degrading potentials of single and consortium autochthonous bacterial population was carried out using standard analytical procedures. Three autochthonous bacterial species; Pseudomonas aeruginosa, Bacillus cibi and Bacillus subtilis were associated with the OS. The isolates exhibited varying OS utilizing and biosurfactant producing potentials. P. aeruginosa was the best OS utilizer while B. subtilis was the best biosurfactant producer (emulsification index of 15.6%). Degradation of the OS with single culture of the best OS utilizer (P. aeruginosa) and consortium of the best OS utilizer and best biosurfactant producer (B. subtilis) revealed that the consortium exhibited a remarkable potential to reduce the total petroleum concentration in the OS from 100.73 ppm to 41.39 ppm (58.91% degradation) as compared to 51.74 ppm (48.7% degradation) achieved by the single culture. The saturated fraction of the OS was the most susceptible to degradation followed by the aromatic faction while the NSO and asphaltene fraction were the least degraded. P. aeruginosa was able to reduce the saturated hydrocarbon content in the OS by 87.4% while a 95.5% reduction was recorded for the consortium. Similarly, the concentration of PAH in the OS was reduced from 27.94 ppm to 16.74 ppm by the single culture and 12.75 by the consortium. The potentials of these bacterial communities can be explored for broader use in remediating oily sludge contaminated soil as well as managing oily sludge waste in the oil and gas industry.

Effect of Incorporation of Potash from Ficus carica Fruit Peel Waste into Potash (Nikkih) from Plantain Peel Waste as Emulsifiers on the Physico-Chemical, Functional Properties, and Acceptability of Yellow Achu Soup

Yellow Achu soup used to eat achu is an emulsion composed primarily of red palm oil and water stabilized by potash as an emulsifier, is regarded as one of the prestigious traditional foods in Cameroon. However, the yellow achu soup faces a problem of stability due to the inability of the potash from plantain peel alone, commonly called Nikkih, to emulsify and stabilize it. This study was therefore aimed at investigating the effect of incorporation of potash from Ficus carica fruit peel to potash from plantain peel, Nikkih, on the emulsification, emulsion stability, and acceptability of yellow achu soup. To this effect, ashes obtained from plantain peels and Ficus carica fruit peel were extracted with water to get their respective crude extracts, potash, with concentrations of 0.07g/ml or 1g/15ml. A mixture experimental design was used to mix different proportions of the plantain peels to Ficus carica fruit peel potash to get 7 samples of the emulsifier, ranging from 100:0, 80:20, 70:30, 60:40, 50:50, 30:70 0:100 denoted as IKM, KIM, MKI, IMK, MIK, KMI, and KKI respectively. The yellow achu soup obtained thereafter was prepared by mixing thoroughly 20ml of partially bleached palm oil, 10ml of emulsifier solution, and 70ml of water at 800C. The pH, emulsification index, foaming capacity, and foam stability of the resulting soup were analyzed followed by an evaluation of its acceptability. The pH of the mixture varied from 11.75 to 11.01, with a pH of 11.53 obtained for the plantain peel crude extract, IMK, and the lowest pH of 11.01 ± 0.01 obtained from the Ficus carica fruit peel ash extract, KKI. The highest alkalinity of 11.75 ± 0.02 for the mixture was obtained at a mixture ratio of 60:40 for sample IMK. The pH of the resulting yellow achu soup decreased as the incorporation ratio increased, with the highest pH of 11.49 using only the plantain crude extract, IKM, to the lowest pH of 10.58 using only the Ficus carica fruit peel ash extract, KKI. The foaming capacity of the yellow achu soup varied from 10.76 ± 2.78% representing the highest for sample IMK while the lowest value was 5.36 ± 0.18% using sample KIM. The foam stability varied from 11.89 ± 2.34% for sample IMK to 4.67 ± 0.79% for sample KIM. Sample MIK displayed the highest emulsifying activity with a value of 65.15±0.30% and 58.79±8.70% after 24 hrs and 48hrs respectively, while KIM had the lowest emulsifying activity of 34.21±0.54% after 24 hours and 34.17±0.23 after 48hours. Out of the ten panelists involved in the sensory evaluation, 50% generally accepted sample MIK, 20% accepted IMK and KMI while 10% preferred MKI. The incorporation of the Ficus carica fruit peel potash to Nikkih serves as a good strategy to improve on the functional properties and acceptability of yellow achu soup.

Screening of Bacteria for Biosurfactants, Exopolysaccharides and Biofilms and their Impact on Growth Stimulation of Zea mays Grown under Petrol Stress

Environmental stress imposed by petroleum hydrocarbons can compensate by use of auxin-producing bacteria having potential for biosurfactants production, to assist improved plants’ growth in petrol contaminated areas. In the present work, four auxin-producing bacteria were screened for biosurfactants, exopolysaccharides (EPS) and biofilms production capability. We hypothesized that Enterobacter sp. (A5C) was the most efficient strain with respect to biosurfactant production and can accumulate EPS as well as biofilms. This strain was attributed to exhibit emulsification index, percentage of hydrophobicity and percentage of hydrocarbon degradation more than 50%. Also, it produced 9.27 mg of EPS per 100 mL of culture while Fourier transform infrared spectroscopy (FTIR) confirmed the presence of alcoholic and carboxylic groups, ketone and sugars in it. Results of in vitro plant microbe interaction assay revealed its potential to stimulate the growth of Zea mays L. plants under 1 and 2% of petrol stress by improving physio-chemical attributes of treated plants, over control. Thus, it is concluded that the test organism i.e., Enterobacter sp. (A5C) might be involved in developing bacterial community (EPS and biofilms) that helped to colonize the bacteria to the plant roots and soil particles that ultimately encouraged the more access to nutrients and protection of plant roots from toxins in soil ecosystem. © 2021 Friends Science Publishers

Characterization of Biosurfactant From Pseudomonas Stutzeri SJ3 for Remediation of Crude Oil-Contaminated Soil

In the present work, production of biosurfactant was studied from the bacterial strains isolated from the soil samples collected from oil contaminated sites in Karaikal ONGC, Puducherry, India. Six morphologically different hydrocarbonoclastic bacterial strains (SJ1-SJ6) isolated on oil agar plates were further screened for biosurfactant production. Based on the screening methods results of 26 mm oil displacement zone, positive results of drop collapse test, 68.14% emulsification index (E24) and 79.2% of bacterial adherence percentage, the isolate SJ3 was selected as the most potent strain and it was identified as P. stutzeri using standard biochemical and 16S rRNA gene sequencing-based methods. Optimization of the P. stutzeri strain showed 36 h incubation, 150 rpm agitation, pH 7.5, 37oC, 1% salinity, 2% glucose as carbon source and 1% yeast extract as nitrogen source were the ideal conditions for growth and the biosurfactant production was found to be growth dependent. The crude biosurfactant showed broad range of antibacterial activity against the bacterial pathogens tested. The P. stutzeri isolated from oil spill site showed biosurfactant with antibacterial activities.

Potential of Enterococcus Faecium LM5.2 for Lipopeptide Biosurfactant Production and Its Effect on the Growth of Maize (Zea Mays L.)

The lipopeptide biosurfactants' chemical characteristics from the lactic acid bacteria isolated from milk and milk products were studied and their effect on maize plant growth. The oil displacement test was performed as a primary screening method to select the BS producing bacteria. Enterococcus faecium LM5.2 had the maximum emulsification index of 45.1±3 and reduced the surface tension to 32.98 ± 0.23% among all the isolates. E. faecium LM5.2 efficiently produced 945.26 ± 4.62 mg/l biosurfactants within 48 hours in MRS broth under the optimum conditions. The confirmation of the identity of the isolate LM5.2 was done with physiochemical tests and 16S rRNA gene sequencing. The molecular phylogenetic relationship was evaluated by the Neighbour-Joining phylogenetic method. The biosurfactant was purified by TLC and identified as lipopeptide-like iturines and surfactins based on Rf values. Mass spectroscopy, NMR, and FTIR analysis also confirmed the biosurfactant's identity as the derivatives of iturin and surfactin. Both the biosurfactant and its producer bacterium were evaluated for their plant growth-promoting activity, and it was found that the biosurfactant and the bacterium could enhance plant growth. To the best of our knowledge, this is the first report of lipopeptide biosurfactant production from Enterococcus faecium. Moreover, the study also showed that the biosurfactant and biosurfactant producing E. faecium LM5.2 could be an eco-friendly plant growth-promoting agent.

Genetic engineering of the precursor supply pathway for the overproduction of the nC14-surfactin isoform with promising MEOR applications

Background Surfactin, a representative biosurfactant of lipopeptide mainly produced by Bacillus subtilis, consists of a cyclic heptapeptide linked to a β-hydroxy fatty acid chain. The functional activity of surfactin is closely related to the length and isomerism of the fatty acid chain. Results In this study, the fatty acid precursor supply pathway in Bacillus subtilis 168 for surfactin production was strengthened through two steps. Firstly, pathways competing for the precursors were eliminated with inactivation of pps and pks. Secondly, the plant medium-chain acyl-carrier protein (ACP) thioesterase (BTE) from Umbellularia californica was overexpressed. As a result, the surfactin titer after 24 h of cultivation improved by 34%, and the production rate increased from 0.112 to 0.177 g/L/h. The isoforms identified by RP-HPLC and GC–MS showed that the proportion of nC14-surfactin increased 6.4 times compared to the control strain. A comparison of further properties revealed that the product with more nC14-surfactin had higher surface activity and better performance in oil-washing. Finally, the product with more nC14-surfactin isoform had a higher hydrocarbon-emulsification index, and it increased the water-wettability of the oil-saturated silicate surface. Conclusion The obtained results identified that enhancing the supply of fatty acid precursor is very essential for the synthesis of surfactin. At the same time, this study also proved that thioesterase BTE can promote the production of nC14-surfactin and experimentally demonstrated its higher surface activity and better performance in oil-washing. These results are of great significance for the MEOR application of surfactin. Graphic abstract

Isolation and Identification of Biosurfactant Producing Bacteria From Workshop Wastewater

Automotive workshop activities produce oil ills that may pollute waters around the workshop area. The oil-polluted water may inhabit biosurfactant producing bacteria that are able to degrade the oil. A study aimed to isolate and identify the bacteria has been conducted from July to September 2020. The bacteria samples were sampled from workshop wastewater at Kubang Raya street KM 2,5 Pekanbaru, Riau Province and sampling were conducted three times. The bacteria were isolated using TSB (Tryptone Soy Broth) and TSA (Tryptone Soy Agar) media and were identified by using biochemical methods. Results showed that there were seven types of bacteria, namely Providencia, Proteus, Acinetobacter, Bacillus, Aeromonas, Proteus and Serratia. The Emulsification index of Providencia was 38.8%, Proteus 50%, Acinetobacter 48.8%, Bacillus 52,1%, Aeromonas 47,6%, Proteus 54,7% and Serratia 48,8%. Data obtained from this study showed that all of the identified bacteria are able to produce biosurfactants.