MOSP - Macao Scientific Publishers

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Optimization of culture conditions for thermostable chitinase production by Paenibacillus sp. D1

Anil Kumar Singh

Abstract: A hyper-chitinase producing isolate Paenibacillus sp. D1 was obtained from common effluent treatment plant of seafood industries at Veraval (Gujarat, India). The isolate exhibited chitinase production over a wide temperature (25 - 45°C) and pH (6 - 9) range with maxima at 30°C in medium with initial pH 7.0. The crude chitinase had activity in broad pH (4 - 10) and temperature (30 - 60°C) range with optima at pH 5.0 and 50°C, respectively. The enzyme was highly thermostable with t1/2 of 36 to 60 h at 40 and 45°C. Crab shell chitin, urea and K2HPO4 were identified as best carbon, nitrogen and phosphorous sources influencing chitinase production by Paenibacillus sp. D1. Addition of tween 80 and FeCl3 enhanced the chitinase production by 1.44 and 1.33 fold, respectively. Identification of essential nutrients affecting chitinase production by Paenibacillus sp. D1 would help to formulate a suitable medium for its production. Moreover, low cost chitin from crab shells can be used as carbon source for thermostable chitinase production by the isolate for industrial and agricultural applications.[...] Read More.

Keywords: Paenibacillus, optimization, thermostable, chitinase.

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Reduction of enterotoxigenic Escherichia coli colonization by the oral administration of Lactobacillus casei as a probiotic in a murine model

Reza Mirnejad*, Jafari Hossein, Abdolla Ardebilli and Hamid babavalian

Abstract: The aim of this study was to examine the reduction of enterotoxigenic Escherichia coli (ETEC) colonization by oral administration of Lactobacillus casei as probiotic in a murine model. In this study, thirty-six BALB/c mice were divided to two test groups and one control group. One of the test groups was fed probiotic bacteria at six days and other groups at three days; whereas, the control group did not receive any probiotic. 72 h after the last oral administration of probiotic, the all three groups were fed by the ETEC. Than, the numbers of E. coli excreted from animal intestinal were determined at various times by colony counting on specific culture media and assessed their rate of colonization. The results of this study showed that L. casei is enable to be colonize in the murine gastrointestinal tract and both test groups of murine show significant decrease of ETEC excretion compared to control group (P = 0.001) . Also, comparison of test groups indicated that longer time reception of probiotic bacteria resulted in more reduction of colonization of pathogenic bacteria. These findings suggest that L. casei can be used as a candidate probiotic to reduce the rate of colonization and establishment of ETEC in the digestive tract and to prevent diarrhea caused by this organism.[...] Read More.

Keywords: Lactobacillus casei sp. strain GG, Escherichia coli, probiotic, enterotoxigenic traveler's diarrhea, bacteriotherapy.

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In vitro activities of three kinds of antibiotics against Staphylococcal biofilm and planktonic cultures

T. El-Banna, A. Abd El-Aziz, A. Abo-Kamar, A. Ghazal and R. AboZahra*

Abstract: The aim of the present study is to determine the activities of three kinds of antibiotics against Staphylococcal biofilm and planktonic cultures in vitro, and to indicate the enhancement of biofilm formation in response to stress factors such as glucose and sub-inhibitory concentrations of antibiotics by using scanning electron microscope. Biofilm forming staphylococci were identified by using the modified microtiter plate method. And the effect of different concentrations of several antibiotics (including ciprofloxacin, gentamycin and amoxicillin-clavulanic acid) on eight isolates was determined. The result showed that out of 86 Staphylococcal isolates, eight strains were found to be strong biofilm forming. Sub-MIC of the antimicrobial agents used increased the biofilm formation in some isolates. However, the preformed biofilm was very difficult to remove with most isolates even with multiples of the MIC. The biofilm MBC reached 46 times the planktonic MBC in some isolates. Scanning electron micrographs of staphylococcus aureus isolate (45S) were made in order to confirm the enhanced biofilm formation in the presence of glucose and sub-MIC of ciprofloxacin and it was found that the slime layer production increases in the presence of glucose and low concentration of ciprofloxacin.[...] Read More.

Keywords: Staphylococcal biofilms, scanning electron micrograph, antimicrobial sub-MIC activity.

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Investigation of in vitro effects of daptomycin, tigecycline and teicoplanin combinations against MRSA, VISA and VRE strains

Ahmet Yilmaz Coban*, Aydin Deveci, Ozlem Acicbe, Nuriye Tasdelen Fisgin, Alper Ciftci, Basak Dokuzoguz and Belma Durupinar

Abstract: Multidrug resistant (MDR) gram positive infectious agents can cause severe infections and monotherapy of these infections by current available antimicrobial agents can be problematic. Therefore, antimicrobial combination therapy may be needed for effective treatment. The study aimed to investigate in vitro effects of binary combinations of tigecycline (TGC), daptomycin (DPC) and teicoplanin (TP) against 4 methicillin resistant Staphylococcus aureus (MRSA), 2 vancomycin intermediate S. aureus (VISA) and 9 vancomycin resistant enterococci (VRE) species by E test method. Whilst, all binary combination of TGC, DPC and TP showed synergistic effect against standard strain of S. aureus and 50% of clinical MRSA isolates, all of the combinations except DPC-TP combination showed additive effect against VISA strains (Mu 3 and Mu 50). TGC-TP, DPC-TP and TGC-DPC combinations showed additive effect against 25, 60 and 50% of clinical VRE isolates, respectively. Synergistic effect was observed in combinations of TGC-TP and DPC-TGC against 2 and 1 VRE clinical isolates, respectively. Combinations of TP with any of TGC and DPC brought MIC values of TP below the level of sensitivity in all of TP resistant VRE and VISA isolates. Antagonistic effect was not observed in combinations of tested drugs against any strains. In conclusion, in vitro effectiveness of these drug combinations may reflect advantages in clinical practice for severe MDR gram positive bacterial infections.[...] Read More.

Keywords: Multidrug resistant, antimicrobial agents, methicillin resistant Staphylococcus aureus, infectious agents, vancomycin resistant enterococci.

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A binding of ECM proteins - collagen, fibronectin, albumin and vitronectin by Bacteriocinogennic enterococci isolated from chicken and rabbits

Igor Štyriak*, Viola Strompfová, Iveta Štyriaková, Monika Simonová and Andrea Lauková

Abstract: Ten Bacteriocinogennic enterococci, isolates from chicken and rabbits, were examined for their binding of collagen, fibronectin, albumin and vitronectin in tubes with Nutrient broth No.2. For ECM binding examination, enterococci were grown in MRS broth under normal air conditions at 37°C. Individual strains expressed binding of selected glycoproteins to various degrees, however, vitronectin was bound the best from these four ECM proteins. These observations lead to suggestion that at least one mode of enterococcal attachment utilizes glycosaminoglycan chains present on the surface of adherent cells. Significance and impact of the study is that some animal strains are comparable with the commercially used strains with respect to their ECM ability. As this feature is important for probiotic bacteria to be able to colonize intestine, these strains could be considered for their wider use in fermented feed for animals.[...] Read More.

Keywords: Enterococcus, extracellular matrix, collagen, fibronectin, albumin and vitronectin.

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Determination of the ability of microorganisms isolated from mechanic soil to utilise lubricating oil as carbon source

A. Sebiomo*, S. A. Bankole and A. O. Awosanya

Abstract: Ten bacteria and five fungi capable of utilising lubricating oil as carbon source were isolated from mechanic soil. The growth profiles were determined by monitoring the optical density, total viable counts, dry weights and pH of the culture utilizing lubricating oil as sole carbon and energy source. The total viable counts increased significantly with optical density and dry weights of fungi as the days of incubation progressed until the 14th day (P < 0.001). There was significant decrease in pH (P < 0.001) as fungal cells metabolised lubricating oil, Pseudomonas aeruginosa produced the highest optical density and viable count values of 0.441 and 8.31 to the end of 14th day of incubation among all bacterial isolates used in this study. P. aeruginosa also presented lowest pH value of 6.53 after 14 days of incubation between all bacterial isolates. Bacillus licheniformis and Enterobacter aerogenes recorded the lowest optical density and viable count values of 0.19 and 8.1 of all bacterial isolates after 14th day of incubation, Enterobacter aerogenes had the highest pH value of 6.8. Of all the fungal isolates used in this study Aspergillus niger and Aspergillus terreus recorded the highest dry weight and viable count values of 19.3 and 6.41. Trichoderma sp. had the lowest pH, dry weight and viable count values of 5.1, 17 and 6.3, respectively, Aspergillus flavus had the highest pH of 5.6. Correlation analysis indicated negative correlation between optical density and pH (correlation coefficient = +0.174) and between viable counts and pH (correlation coefficient = +0.159), there was positive correlation between viable counts and optical density (correlation coefficient = 0.735). For the fungal isolates there was negative correlation between dry weights and pH (correlation coefficient = +0.958) and between viable counts and pH (correlation coefficient = -0.830). The correlation analysis between fungal dry weights and viable counts showed positive correlation (0.786). The utilization of hydrocarbon in lubricating oil resulted in gradual reduction in the oil layer and complete disappearance of the oil with prolonged incubation. This study has shown that the microorganisms isolated from mechanic soils have potential application in the bioremediation of sites polluted with lubricating oil.[...] Read More.

Keywords: Bacteria, fungi, lubricating oil, biodegradation.

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Isolating endophytic fungi from evergreen plants and determining their antifungal activities

Changhong Liu*, Tingting Liu, Fengfeng Yuan and Yucheng Gu

Abstract: A total of 262 strains of endophytic fungi were isolated from 23 evergreen plant species collected from Zijin Mountain in Nanjing, China. Two-hundred and three of the fungi isolates were classified into 23 taxa in 19 genera based on colony morphology and microscopic observation of mycelia and asexual/sexual spores. The highest richness was obtained from Cedrus deodara (28), while the highest diversity of identified species (6) was isolated from Sabina procumbens. Some fungi appeared to be host-specific, such as Botrytis ricini lt300, Geotrichum candidum lt274 and Lacellina graminicola lt256, while other strains (e.g. Alternaria alternata lt222, Anthina sp. Lt147, Colletotrichum gloeosporioids lt305 and Fusarium solani lt293) were commonly isolated from a range of plants. The richness of the endophytic fungi recovered from plant branches was significantly higher than those from leaves. Moreover, about 70% of the obtained endophytic fungi could produce antifungal metabolites against at least one plant pathogenic fungi. The EtOAc extracts of seven species of Anthina sp. lt147, C. gloeosporioids lt305, Ectostroma sp. Lt144, Fusarium decemcellulare lt183, Fusarium oxysporum lt173, Paraconiothyrium brasiliense lt161 and C. montemartinii lt198 showed broad inhibition against the growth of all the six phytopathogens with the inhibition rates from 20 to 80%. These results indicated that endophytic fungi may play an important role in protection of the evergreen plants from disease as well as an excellent resource for searching for natural antifungal compounds.[...] Read More.

Keywords: Endophytic fungi, evergreen plants, antifungal activity.

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Microbial morphology and community structure in a suspended carrier biofilm reactor as a function of substrate loading rates

Fu Bo, Liao Xiaoyi, Ding Lili, Xu Ke and Ren Hongqiang*

Abstract: An aerobic suspended carrier biofilm reactor was efficient in simultaneous organic carbon and nitrogen removal, with COD removal efficiencies of 87.1–99.0% and simultaneous nitrification and denitrification (SND) efficiencies about 96.7-98.8%. The effects of substrate loading on microbial morphology and community structure were investigated by environmental scanning electron microscopy (ESEM), denaturing gel gradient electrophoresis (DGGE) and fluorescence in situ hybridization (FISH). Biofilms formed at different substrate loadings had different morphology and community structures. A higher substrate concentration resulted in denser and thinner biofilms, while a lower substrate concentration resulted in looser and thicker biofilms with significant presence of filamentous bacteria. Both sequence analysis of DGGE bands and FISH analysis indicated the dominance of β-Proteobacteria in the biofilm communities, especially Zoogloea. FISH analysis revealed that the relative abundance of β-proteobacteria ammonia oxidizing bacteria (AOB) was positively correlated with ammonium concentrations, whereas Nitrospira-like nitrite-oxidizing bacteria (NOB) were negatively affected by ammonia and nitrite concentrations. The presence of denitrifying bacteria, Hydrogenophaga spp., Hyphomicrobium spp. and Rhizobium spp. suggested that not only the oxygen microgradients within the biofilm but also aerobic denitrifiers may be responsible for SND in the aerobic biofilm.[...] Read More.

Keywords: Microbial community structure, microbial morphology, substrate loading, suspended carrier biofilm.

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Bacteriological quality of some Nigerian currencies in circulation

S. Awe*, K. I .T. Eniola, F. T. Ojo and A. Sani

Abstract: The bacteriological quality of some Nigerian currencies in circulation was investigated in terms of total bacterial count and kinds of bacterial species present. The notes had high bacterial counts: ranging from 1.5×104 to 4.2×104 cfu/cm2; there was no significant difference in the bacterial counts. Eight bacterial species were isolated: Escherichia coli, Staphylococcus aureus, Proteus mirabilis, Streptococcus faecalis, Klebsiella sp., Pseudomonas aeroginosa, Bacillus subtilis and Salmonella sp. Salmonella sp. was the least prevalent of the bacterial isolates (2%) while S. aureus was the most prevalent (28%). Antibiotic susceptibility pattern suggests that some of the isolates (S. aureus and P. mirabilis) had potentials for multiple antibiotic resistances. The health implications of the organisms encountered are discussed and suggestions are provided to enable safe handling of the notes.[...] Read More.

Keywords: Currencies, naira notes, antibiotic resistance.

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Studies on the culturable marine actinomycetes isolated from the Nahoon beach in the Eastern Cape Province of South Africa

Isoken H. Ogunmwonyi, Ntsikelelo Mazomba, Leonard Mabinya, Elvis Ngwenya, Ezekiel Green, David A. Akinpelu, Ademola O. Olaniran, Kim Bernard and Anthony I. Okoh*

Abstract: A total of 84 culturable marine actinomycetes belonging to 15 generic morphotypes were isolated from water and rock scrapings from the Nahoon beach, a coastal shore of Indian Ocean in the Eastern Cape Province of South Africa. The colonies showed diverse morphological characteristics and their occurrence and distribution varied with sample type. The rock scrappings yielded more actinomycetes morphotypes than the water samples. Streptomyces was most prevalent in both samples. Actinoplane, Actinosynnema, Norcadia, Norcardiopsis, Streptosporagium and Intrasporagium were present in rock scrapings but absent in water samples. Kibdellosporium was present in water sample and absent in rock scrapings. The Streptomyces isolates were selected and preliminarily screened for antimicrobial activity. The bioactive compounds of 10 most potent Streptomyces isolate was extracted twice with equal volume of ethyl acetate (1:1 v/v). The ethyl acetate extracts of the putative Streptomyces isolates showed activities against at least 6 and up to 26 of the 32 test bacteria screened. Inhibition zones were found to range between 9 and 32 mm diameters at a concentration of 10 mg/ml. The partial characterization of the crude extracts by IR spectra analysis revealed the possible presence of terpenoid, long chain fatty acids and secondary amine derivatives compounds in the extracts. We conclude that the Nahoon beach promises to be a veritable resource for diverse marine actinomycetes of potentials for bioactive compounds production and novel drug discovery.[...] Read More.

Keywords: Morphotypes, occurrence, rock scrapings, IR spectral, bioactive compound.

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