ABSTRACT
Fabrication of scaffolds from biomaterials for restoration of defected mandible bone has attained increased attention due to limited accessibility of natural bone for grafting. Hydroxyapatite (Ha), collagen type 1 (Col1) and chitosan (Cs) are widely used biomaterials which could be fabricated as a scaffold to overcome the paucity of bone substitutes. Here, rabbit Col1, shrimp Cs and bovine Ha were extracted and characterized with respect to physicochemical properties. Following the biocompatibility, degradability and cytotoxicity tests for Ha, Col1 and Cs a hydroxyapatite/collagen/chitosan (Ha·Col1·Cs) scaffold was fabricated using thermally induced phase separation technique. This scaffold was cross-linked with (1) either glutaraldehyde (GTA), (2) de-hydrothermal treatment (DTH), (3) irradiation (IR) and (4) 2-hydroxyethyl methacrylate (HEMA), resulting in four independent types (Ha·Col1·Cs-GTA, Ha·Col1·Cs-IR, Ha·Col1·Cs-DTH and Ha·Col1·Cs-HEMA). The developed composite scaffolds were porous with 3D interconnected fiber microstructure. However, Ha·Col1·Cs-IR and Ha·Col1·Cs-GTA showed better hydrophilicity and biodegradability. All four scaffolds showed desirable blood biocompatibility without cytotoxicity for brine shrimp. In vitro studies in the presence of human amniotic fluid-derived mesenchymal stem cells revealed that Ha·Col1·Cs-IR and Ha·Col1·Cs-DHT scaffolds were non-cytotoxic and compatible for cell attachment, growth and mineralization. Further, grafting of Ha·Col1·Cs-IR and Ha·Col1·Cs-DHT was performed in a surgically created non-load-bearing rabbit maxillofacial mandible defect model. Histological and radiological observations indicated the restoration of defected bone. Ha·Col1·Cs-IR and Ha·Col1·Cs-DHT could be used as an alternative treatment in bone defects and may contribute to further development of scaffolds for bone tissue engineering.
ABSTRACT
INTRODUCTION: Although antibiotics have revolutionized health care by saving lives, the evolution of both pathogenic and commensal antibiotic-resistant bacteria are emerging as a threat in the health sector. As for Lactobacillus spp., it is usually a non-pathogenic bacteria. However, it can cause infection in immunocompromised condition. In this study, Lactobacillus spp. has been isolated from the faeces of infants with Hirschsprung disease (HD), which is congenital aganglionosis of intestine, where surgical approach and antibiotics are frequently used as medical intervention. The aim of this study is to assess the antibiotic resistance pattern and determine the presence of resistance genes, if any, in Lactobacillus spp. isolated from HD infants with ileostomy. METHODOLOGY: Six Lactobacillus spp. were isolated from faeces of six HD infants and confirmed using both conventional and molecular methods. Antibiotic resistance pattern was checked through disc diffusion method and was further investigated for the presence of antibiotic resistance genes (blaTEM, blaCTX-M, blaOXA-2, blaIMP, blaVIM-2, blaNDM-1 and mcr-1). RESULTS: Antibiotic susceptibility of the isolates showed high level of resistance towards cephalosporins, oxacillin, aztreonam, meropenem and polymyxin group. However, four of the isolates showed the presence of blaCTX-M gene after PCR amplification. CONCLUSIONS: To our knowledge, this is the first report on the presence of antibiotic resistance gene blaCTX-M in Lactobacillus spp. and this presence may pose a serious threat in treatment regimen. As not much is known regarding the presence of blaCTX-M in Lactobacillus spp., this finding may provide new light to research on antibiotic resistance in gut microflora.
Subject(s)
Drug Resistance, Bacterial/genetics , Hirschsprung Disease/microbiology , Lactobacillus/genetics , Anti-Bacterial Agents/pharmacology , Feces/microbiology , Humans , Infant , Lactobacillus/drug effects , Lactobacillus/isolation & purification , Microbial Sensitivity Tests , Surgical StomasABSTRACT
Background: The requirement of an alternative clean energy source is increasing with the elevating energy demand of modern age. Bioethanol is considered as an excellent candidate to satiate this demand. Methods: Yeast isolates were used for the production of bioethanol using cellulosic vegetable wastes as substrate. Efficient bioconversion of lignocellulosic biomass into ethanol was achieved by the action of cellulolytic bacteria ( Bacillus subtilis). After proper isolation, identification and characterization of stress tolerances (thermo-, ethanol-, pH-, osmo- & sugar tolerance), optimization of physiochemical parameters for ethanol production by the yeast isolates was assessed. Very inexpensive and easily available raw materials (vegetable peels) were used as fermentation media. Fermentation was optimized with respect to temperature, reducing sugar concentration and pH. Results: It was observed that temperatures of 30°C and pH 6.0 were optimum for fermentation with a maximum yield of ethanol. The results indicated an overall increase in yields upon the pretreatment of Bacillus subtilis; maximum ethanol percentages for isolate SC1 obtained after 48-hour incubation under pretreated substrate was 14.17% in contrast to untreated media which yielded 6.21% after the same period. Isolate with the highest ethanol production capability was identified as members of the ethanol-producing Saccharomyces species after stress tolerance studies and biochemical characterization using Analytical Profile Index (API) ® 20C AUX and nitrate broth test. Introduction of Bacillus subtilis increased the alcohol production rate from the fermentation of cellulosic materials. Conclusions: The study suggested that the kitchen waste can serve as an excellent raw material in ethanol fermentation.
ABSTRACT
INTRODUCTION: Mango juice has always been considered as a delicious, nutritious popular drink, but processed juice may not always be safe due to chemical and microbial risks. Determination of physicochemical and microbiological qualities of some packed mango juices of Bangladesh will help consumers to know the present scenario. MATERIAL AND METHODS: Six commercially available different juice samples were collected from the market. Carbohydrate profiles were determined using HPLC, crude protein content was calculated using the Kjeldahl method and other parameters were determined by standard AOAC methods. Standard culture techniques were followed to assess the total viable count (TVC), E. coli and other fecal coliforms. RESULTS: The highest quantity of monosaccharide (58.88%) was recorded in the AC1ME5 brand, while the lowest in Homemade (5.648%) and MN1GL2 (9.867%). The maximum content of acidity recorded was 0.24% and minimum 0.21%. The TSS content of all samples varied from 19% to 12%. The highest quantity 6.87% and the lowest 3.62% of reducing sugar were recorded. Most of the mango juices were low in protein and very low/negligible in fat content. Total viable count of different types of fruit juices varied from 1×103 - 3×103 CFU/ml. No significant amount of E. coli and fecal coliform was detected. CONCLUSION: It can be concluded that the locally available mango juices contain a safe level of nutritional and microbial elements for human consumption, but not highly satisfactory.
ABSTRACT
In view of the anticipated shortage of the traditional supplies of fossil fuels, there is a great deal of interest in the production of ethanol as an alternative biofuel in recent years. The main objective of this research work was to isolate and characterize stress tolerant, high potential ethanol producing yeast strains from various fruit peel. Two yeast isolates from pineapple (Pa) and orange (Or) have been isolated, characterized on the basis of morphological and physic-chemical characters and optimized on ethanol producing capability using sugarcane molasses as substrate. Ethanol production percentage was estimated by Conway method. Isolates were thermotolerant, pH tolerant, ethanol tolerant as well as osmotolerant. They were resistant to Chloramphenicol (30 µg/disc) and Nalidixic acid (30 µg/disc). The isolates showed no killer toxin activity against E. coli. The highest production capacity of the yeasts was found to be 7.39% and 5.02% for Pa and Or, respectively, at pH 5.0, 30 °C temperature in media with an initial reducing sugar concentration of 6.5% for Pa and 5.5% for Or (shaking). Addition of metal ions increased the rate of ethanol production highest to 10.61% by KH2PO4. This study revealed that indigenous yeast isolates could be used to benefit the fuel demand and industrial alcohol industries.
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The coastal aquaculture mainly shrimps constitute major export sector in Bangladesh and is increasingly shaped by international trade conditions and by national responses to those stringent quality and safety standards. PCR based validated methods for detection of major bacterial pathogens in shrimp might be very useful tool for ensuring quality and safety standards of exportable shrimps. The objective of this study was to evaluate overall performance (sensitivity and specificity) of the multiplex PCR assay for detection of Vibrio cholerae, Vibrio parahaemolyticus, Salmonella sp. and Escherichia coli O157:H7 from spiked shrimp samples. The targeted genes were ompW for V. cholerae, tdh for V. parahaemolyticus, sefA for Salmonella spp. and hlyEHEC for E. coli O157:H7. The genomic DNA was extracted by using standard method and amplified accordingly. Sensitivity of the assay was tested by inoculating the shrimp homogenate with viable cells of laboratory references strains (target pathogens). The genes were amplified individually both from culture homogenate and spiked samples. Twenty different uniplex and multiplex PCR assay were performed; the results showed that the sensitivity and specificity of multiplex PCR are comparable to that of the results of uniplex PCR for the samples. DNA extracted from shrimp samples spiked with non-target pathogen (Bacillus cereus, Shigella flexneri and Staphylococcus aureus) yielded negative results.
