MOSP - Macao Scientific Publishers

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Microbiology of polyethylene-packaged sliced watermelon (Citrullus lanatus) sold by street vendors in Nigeria

E. Nwachukwu*, C. F. Ezeama and B. N. Ezeanya.

Abstract: Ten packaged, freshly sliced watermelon were collected from different street vendors to determine their microbiological quality. Eight different microbial isolates were obtained from the sliced watermelon samples, namely Escherichia coli, Klebsiella aerogenes, Proteus mirabilis, Staphylococcus aureus, Lactobacillus spp., Saccharomyces cerevisiae, Rhizopus stolonifer and Mucor spp. The effects of high density polyethylene (HDP) and low density polyethylene (LDP) packaging bags on the microbiological quality of freshly sliced watermelon, stored at ambient temperature were also determined. After 10 days of storage, the total viable counts increased from 0.6 x 103 cfu/g to 5.3 x 103cfu/g and to 5.5 x 103 cfu/g in the HDP- and LDP-packaged watermelon samples, respectively. The total fungal counts increased from 0.5 x 103cfu/g to 6.7 x 103cfu/g and to 7.2 x 103cfu/g in the HDP- and LDP-packaged watermelon samples, respectively. Proper sanitation practice and use of good quality packaging materials are recommended in order to avoid risks associated with the consumption of sliced food produce.[...] Read More.

Keywords: Watermelon, microbiological quality, packaging materials.

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In vitro screening of antibacterial activity of aqueous and alcoholic extracts of various Indian plant species against selected pathogens from Enterobacteriaceae

Parekh J and Chanda S*

Abstract: Thirty four medicinal plants, belonging to twenty eight different families, were screened for potential antibacterial activity against six bacterial strains belonging to Enterobacteriaceae, viz. Enterobacter aerogenes ATCC13048, Escherichia coli ATCC25922, Klebsiella pneumoniae NCIM2719, Proteus mirabilis NCIM 2241, Proteus vulgaris NCTC8313, and Salmonella typhimurium ATCC23564. Antibacterial activity of aqueous and alcoholic extracts was tested by the agar disc diffusion and agar well diffusion methods. The ethanol/methanol extracts were more active than aqueous extracts for all the plants studied. The most susceptible bacterium was K. pneumoniae, while the most resistant bacteria were S. typhimurium and E. coli. From the screening experiment, Woodfordia fruticosa Kurz. showed best antibacterial activity. Hence, this plant may be used further to isolate and evaluate the therapeutic antimicrobials.[...] Read More.

Keywords: Medicinal plants, antibacterial activity, aqueous extracts, alcoholic extracts, Enterobacteriaceae.

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Biodegradation of hydrocarbons in untreated produce water using pure fungal cultures

C. C. Okoro

Abstract: Biodegradation studies of hydrocarbons in untreated produce water from an oil production facility in Nigeria were undertaken over a period of time using pure fungal cultures (Penicillium sp. and Aspergillus niger). The rate of reduction in some petroleum hydrocarbon fractions, such as n-alkanes, aromatics, nitrogen, sulfur and oxygen (NSO)-containing compounds and polycyclic aromatic hydrocarbons (PAHs), were monitored by means of gas chromatography and mass spectrometery, using mechanically treated produce water as a reference. Gas chromatographic analysis showed that untreated produce water with an oil and grease content of 1407 mg/l contained various petroleum hydrocarbon fractions, including n- alkanes (608 mg/l), aromatics (13.88 mg/l), NSO compounds (12.68 mg/l) and PAHs (0.833 mg/l). Upon mechanical treatment, the oil and grease content of the produce water was reduced to 44 mg/l, while n-alkanes, aromatics, NSO compounds and PAHs were reduced to 38.4, 2.65, 1.78 and 0.0655 mg/l, respectively.A pure culture of Penicillium sp. reduced the oil and grease content to 72.3 mg/l, comprising of n-alkanes (65.50 mg/l), aromatics (0.98 mg/l), NSO compounds (1.64 mg/l) and PAHs (0.0021 mg/l) after 120 days of exposure. However, A. niger reduced the oil and grease content to 59.1 mg/l, comprising of n-alkanes (56.50 mg/l), aromatics (0.65 mg/l), NSO compounds (0.96 mg/l) and PAHs (0.008 mg/l) after 120 days of exposure. The results indicate that produce water is readily biodegradable and that fungal cultures have the capability to degrade the recalcitrant PAH component of the petroleum hydrocarbon mixture in produce water. Biodegradation rates were, however, slightly more enhanced by using A. niger than Penicillium sp.[...] Read More.

Keywords: Biodegradation, fungal cultures, petroleum hydrocarbons,produce water.

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In vitro anti-bacterial activity of a novel isoquinoline derivative and its post antibacterial effects on Pseudomonas aeruginosa

Piyush Bihari Lal, Naresh Kumar, Tasleem Arif, T. K. Mandal, K. Akhilesh Verma, G. L. Sharma and Rajesh Dabur*

Abstract: The isoquinolines are of great importance to humanity because of their medicinal value and different structure. There have been many researches on the isoquinolines, but relatively few pure compounds have been investigated for their antibacterial activity. The in vitro activity of a novel synthetic antimicrobial compound 1-(4-choloro-phenyl)-6,7-dimethoxy-2-methyl-1,2,3,4,- tetrahydroisoquinoline was evaluated against Pseudomonas aeruginosa (ATCC27853) using standard methods approved by Clinical and Laboratory Standards Institute. The minimum inhibitory concentration of the compound which inhibited more than 90% growth (MIC90) of P. aeruginosa was found to be ranged from 24.0 to 6.0 g ml-1 in different media. The ET50 (concentration which lyses 50% erythrocytes) of the compound was observed to be 450 g ml-1. It was found that the compound down-regulated the expression of PQS, elastase and pyocyanin, the important virulence factors of P. aeruginosa. Proteomics studies revealed that the compound inhibited/down regulated the expression of PhnA and oprL proteins of P. aeruginosa which are crucial for PQS synthesis and membrane integrity. This type of compounds may provide avenue for the discovery of clinically useful antibacterial drugs.[...] Read More.

Keywords: Isoquinoline, P. aeruginosa, virulent factors, antimicrobial activity, proteomics.

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Chemical composition, antioxidant and antimicrobial properties of the essential oil of Dacryodes edulis (G. Don) H. J. Lam from Gabon

L. C. Obame, P. Edou, I. H. N. Bassolé*, J. Koudou, H. Agnaniet, F. Eba and A. S. Traore

Abstract: The essential oil obtained by hydrodistillation from the resin of Dacryodes edulis (G. Don) H. J. Lam was simultaneously analyzed by gas chromatography (GC) and gas chromatography-mass spectrometry (GC -MS). Twenty four components were identified in the essential oil and the main components were sabinene (21.8%), terpinene-4-ol (19.8%), -pinene (17.5%) and p-cymene (11.3%), respectively. The antioxidant capacity of the essential oil was examined using an in vitro radical scavenging activity test and -carotene-linoleic acid assays. In the 2.2-Diphenylpicrylhydrazyl (DPPH) test system, the IC50 value of D. edulis oil was 68.5 ± 2.29 µg/ml. In the -carotene-linoleic acid test system, oxidation of linoleic acid was effectively inhibited by D. edulis (70.0%). The oil was less effective than butylated hydroxytoluene (BHT). Furthermore, the essential oil was evaluated for its antimicrobial activity using disc diffusion and microdilution methods. The essential oil showed better activity against bacterial species than against yeast.[...] Read More.

Keywords: Dacryodes edulis, Burseraceae, essential oil, antimicrobial activity; antioxidant activity; gas chromatography-mass spectrometry.

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In vitro detection and characterization of bacteriocin-like inhibitory activity of lactic acid bacteria (LAB) isolated from Senegalese local food products

Michel Bakar DIOP, Robin DUBOIS-DAUPHIN, Carine DORTU, Jacqueline DESTAIN, Emmanuel TINE, and Philippe THONART,

Abstract: The prevalence of lactic acid bacteria (LAB) in Senegalese local food products was determined to be 109 CFU/g in millet flour and milk products, and 103 CFU/g in seafood products. These food products are generally preserved by spontaneous fermentation (without addition of starters). Of 220 lactic acid bacteria strains randomly selected from such products, 12 isolates capable of producing bacteriocin-like substances (bac+) were detected. Based on the use of API 50 CH test kits and 16S rDNA sequencing, 11 isolates were characterized as Lactococcus lactis subsp. lactis strains and one as an Enterococcus faecium strain. Nisin- and enterocin B-encoding genes were respectively identified in the bac+ lactococcal strains and the E. faecium strain. Since the bac+ Lc. lactis strains were isolated from different products, it suggests a high potential of growth by these strains in variable ecological environments. Expression of the nisin gene was indicated for one of the lactococcal strains, designated Lc. lactis subsp. lactis CWBI-B1410, which showed the highest in vitro antibacterial activity. An antibacterial preparation prepared from the CWBI-B1410 strain showed many similarities with nisin with regards to its inhibitory effects, heat resistance, protease sensitivity profile, as well as retention time of the antibacterial substances on a C18 column. These results suggest that a nisin-like substance is produced by the CWBI-B1410 strain. This strain has been selected for application as an additional barrier to supplementation with sodium chloride as a means to improve the bacterial quality of fish commodities in Senegal.[...] Read More.

Keywords: Lactococcus lactis, antimicrobial, bacteriocins, Nisin-like substance.

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Drynaria quercifolia (L.) J.Sm: A potential resource for antibacterial activity

M. Kandhasamy, K. D. Arunachalam* and A. J. Thatheyus

Abstract: Six different organic solvents such as ethanol, methanol, petroleum ether, hexane, benzene and chloroform were used to extract the bioactive compounds from the rhizome of Drynaria quercifolia to screen the antibacterial activity against infectious disease causing bacterial pathogens such as Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, Pseudomonas aeruginosa, Salmonella typhi, Salmonella paratyphi A, Salmonella paratyphi B, Salmonella marscence, Staphylococcus aureus and Bacillus subtilis by agar diffusion method. The ethanolic extract of D. quercifolia was more active against 80% of the organisms tested. It was followed by methanolic extract (70%), benzene (50%) and chloroform extract (40%) in inhibiting the growth of the organisms tested. Petroleum ether and hexane extract of D. quercifolia did not show any antibacterial activity against any of the pathogenic bacteria tested. Among the bacteria tested, gram-negative bacteria were more susceptible to the crude extracts compared to gram-positive bacteria. Among gram-positive bacteria, S. aureus was susceptible to ethanolic, methanolic and chloroform extracts whereas B. subtilis was susceptible to methanolic extract of D. quercifolia alone. In the present study ethanolic and methanolic extracts of rhizome of D. quercifolia showed high efficiency of antibacterial activity and gram-negative bacteria were more susceptible to all the extracts tested.[...] Read More.

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Microbiological quality of water, associated management practices and risks at source, transport and storage points in a rural community of Lungwena, Malawi

Taulo, S., *, Wetlesen, A., Abrahamsen, R., Mkakosya, R. and Kululanga, G.

Abstract: This study investigated and compared the microbiological quality of source, transported and stored water in Lungwena households. It also examined water management practices at all the investigated points. One hundred and eighty (180) water samples were collected from 6 villages and tested for Escherichia coli, Salmonella, E .coli 0157:H7 and Campylobacter jejuni using standard methods. Water contamination practices were observed in two hundred and eighty seven households. E. coli, Salmonella, E. coli 0157:H7 and C. jejuni were isolated in 54, 24, 6.7 and 2.2% of the samples, respectively. Sampling points revealed a significant difference (p = 0.001) in E. coli concentration. Salmonella concentration between sampling points was not significant (p > 0.05). E. coli concentration was significantly (p = 0.042) higher than that of Salmonella spp. The microbiological quality of water was found to be poor as a result of both poor water management practices and environmental sanitation. There were no significant differences (p > 0.05) in water management practices among the villages.[...] Read More.

Keywords: Pathogens, stored water, transport water, water contamination.

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Statistical optimization of medium components for chromate reduction by halophilic Streptomyces sp. MS-2

Mona E. M. Mabrouk

Advanced Journal of Microbiology Research Vol. 2012

Available online at http://internationalscholarsjournals.org/journal/ajmr

Full Length Research Paper

Statistical optimization of medium components for chromate reduction by halophilic Streptomyces sp. MS-2

Mona E. M. Mabrouk

Botany Department, Faculty of Science, Damanhour, Alexandria University, Egypt. E-mail: mona_mabrouk_eg@hotmail.com.

Accepted 18 March, 2012

Extensive use of hexavalent chromium Cr(VI) in various industrial applications has caused substantial environmental contamination. A marine bacterium, Streptomyces sp. MS-2 showed a high Cr(VI) reduction performance. Streptomyces sp. MS-2 completely reduced 75 mg/l Cr(VI) within 72 h of growth. The effectiveness of the bacterium for reducing Cr(VI) under different conditions was evaluated. Optimum pH and temperature were 7.0 and 37^oC, respectively. Statistical screening of medium components for Cr reduction by Streptomyces sp. MS-2 was carried out by Plackett–Burman design. Peptone, yeast extract, inoculum size, and volume of the medium were shown as significant components influencing Cr(VI) reduction. By applying a verification experiment, Streptomyces sp. MS-2 completely reduced 75 mg of Cr(VI) to Cr(III) within 12 h. This optimization strategy led to a 6-fold increase in the reduction rate. This holds great promise for detoxification of Cr(VI) under a wide range of environmental conditions.

Key words: Streptomyces MS-2; hexavalent chromium; Plackett–Burman design.

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Solubilization of inorganic phosphates and plant growth promotion by strains of Pseudomonas fluorescens isolated from acidic soils of Cameroon

FANKEM Henri, NGO NKOT Laurette, DEUBEL Annette, QUINN John, MERBACH Wolfgang, ETOA François-Xavier and NWAGADieudonné*

Abstract: A trial of a screening and selection strategy for phosphate-solubilizing bacteria based on phosphate solubilization ability, and the subsequent effect of these strains on plant growth promotion under in situ conditions was conducted. Of all the bacteria tested, three Pseudomonas fluorescens strains (CB501, CD511 and CE509) were selected. On agar plates, two strains (CB501 and CE509) showed an ability to solubilize the three phosphate types (Ca3 (PO4)2, AlPO 4·H2O or FePO4·2H2O), while strain CD511 showed a halo zone only on an agar plate supplemented with iron phosphate (Fe-P). However, in liquid media, all the strains were able to mobilize significant amounts of phosphorus (P) depending on the phosphate type. Calcium phosphate (Ca-P) solubilization resulted from the combined effects of pH decrease and carboxylic acids synthesis. At pH 4, it was solubilized by most of the organic acids. However, the synthesis of carboxylic acids was the main mechanism involved in the process of aluminium phosphate (Al-P) and Fe-P solubilization. Both were mobilized at pH 4 by citrate, malate, tartrate, and on a much lower level by gluconate and trans-aconitate. Subsequently, a greenhouse trial was conducted using Zea mays, the results of which obtained using 5 parameters including grain yield and P uptake, revealed that strain CB501 was the best plant growth promotor with a global effect of +37%, followed by strain CE509 (+21.2%) and then by strain CD511 (+16.7%). However, the selection of phosphate-solubilizing Pseudomonas strains as possible inoculation tools for phosphate-deficient soils should focus on the integral interpretation of laboratory assays, greenhouse experiments and field trials.[...] Read More.

Keywords: Carboxylic acids, Phosphate solubilization, plant growth, Pseudomonas fluorescens.

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