Isolation and Identification of a New Bacillus cereus Strain and Characterization of its Neopullulanase

Identification and use of more efficient enzymes in the food and pharmaceutical industries is the focus of many researchers. The aim of this study was to search for a new bacterial strain capable of producing high levels of pullulanase applicable to biotechnology, the starch bioprocessing and food industries. A new pullulan hydrolyzing Bacillus strain was isolated and designated SDK2. Morphological and biochemical tests identified the strain as a putative Bacillus cereus strain, which was further characterized and confirmed through 16s rRNA sequencing, and was submitted to GeneBank, under the accession number FR6864500. Quantitative analysis of the strain’s pullulanase activity was carried out by the Dintrosalicyclic (DNS) acid-based assay. Thin layer chromatography (TLC) of the culture supernatant, identified the extracellular pullulanase as neopullulanase. Effects of temperature and pH on pullulanase activity were also studied. The optimum conditions for enzyme activity, as represented by 60°C and a pH of 7, resulted in an activity of 13.43 U/ml, which is much higher than some of the previously reported activities. However, growth of B. cereus SDK2 was also observed at a pH range of 5 to 10, and temperatures of 30°C to 50°C. The effect of metal ions and reagents, such as Mg+2, Ca+2, Zn+2, Cu+2, Fe+2, Ni+2 on enzyme activity showed that Ca+2 ions increased pullulan activity, whereas the other ions and reagents inhibited pullulanase activity. The ability of B. cereus SDK2 to produce high levels of neopullulanase stable at 60°C that can generate panose from pullulan, make this newly isolated strain a valuable source of debranching enzyme for biotechnology, the starch bioprocess and medical industries

High folate production by naturally occurring Lactobacillus sp. with probiotics potential isolated from dairy products in Ilam and Lorestan provinces of Iran

Rapidly proliferating cells require large amounts of folate to support efficient DNA replication, repair and methylation indicating the importance of folate in human metabolism. Milk products are good sources of such vitamins which are produced by probiotics. In order to find suitable strains capable of high folate production, isolation and identification of Lactobacilli in traditional fermented milk from two different provinces located in the west of Iran were carried out. Lactobacillus  bacteria were isolated according to the ISO 7889 standard procedure. The isolated bacteria were characterized phenotypically and were screened for their ability to produce folate during fermentation of skim milk. Folate production by the selected strains was between 2.8 to 66.6 μg/l. Two strains with the highest folate production were then selected. The 16SrRNA genes from these two strains were amplified and sequenced and a phylogenetic tree constructed. The sequencing results in combination with phenotypic and biochemical properties showed that both strains were similar to Lactobacillus crustorum. Therefore, two new strains with an ability of high folate production were isolated and identified. These could be used as probiotics in the dairy industry. Hence, exploiting natural food-grade microorganisms for the production of nutritive dairy products is possible.Keywords: Folate, Lactobacillus, probiotic, traditional dairy products, IranAfrican Journal of Biotechnology Vol. 9(33), pp. 5383-5391, 16 August, 201

Malpighian tubules are important determinants of Pseudomonas transstadial transmission and longtime persistence in Anopheles stephensi

Background: Pseudomonas is a genus of bacteria commonly found in investigations of gut microbes in malaria mosquitoes. Among those mosquitoes is the dominating malaria vector in Asia, Anopheles stephensi, where Pseudomonas is a prevailing bacterium and natural inhabitant of its breeding places. In order to explore the reason for finding Pseudomonas so frequently, an investigation of its localization and transstadial properties was undertaken.Methods: A Pseudomonas isolate from Anopheles stephensi was transformed successfully with an endogenous plasmid modified to express green fluorescent protein (GFP). Subsequently, the Pseudomonas-GFP was added to the laboratory larval breeding place of Anopheles stephensi and taken up by the larvae. After 24 hours, the larvae were cleaned and moved to a bath with double-distilled water. Also, female adults were fed sugar solution containing Pseudomonas-GFP. The Pseudomonas-GFP was traced in the alimentary canal of larvae, pupae and adults.Results: Fluorescent microscopy and PCR assays showed that the Pseudomonas bacteria underwent transstadial transmission from larvae to pupae and then to adults. In blood-fed female mosquitoes, the bacteria increased in numbers and remained in the mosquito body for at least three weeks after eclosion. In addition to the midgut, the Malpighian tubules of both larvae and adult mosquitoes were colonized by the bacteria. Also Pseudomonas-GFP that was distributed through sugar solution was able to colonize the Malpighian tubules of adult females.Conclusions: Colonization of the Malpighian tubules by Pseudomonas bacteria seems to be important for the transstadial passage from larvae to adult and presumably for the longevity of the bacteria in the adult mosquito. The existence of an entry point in the larval stage, and the long duration in the female gut, opens up for a possible use of Pseudomonas in mosquito paratransgenesis

Expression of foreign epitopes in CS3 fimbriae / Bagher Yakhchali.

Includes bibliographies.1 v. : ill. ; 30 cm.Aims to develop the CS3 pile of CFA/II+ of enterotoxigenic E. coli as a delivery system for the expression of foreign antigenic determinants to the bacterial cell surface, and to make an immunogenic ST toxoid as a step towards a vaccine against Enterotoxigenic E. coli.Thesis (Ph.D.)--University of Adelaide, Dept. of Microbiology and Immunology, 199

The Effect of Prebiotic Chitosan on the growth and antimicrobial characteristic of Probiotic lactobacilli

Background and Aim: Nowadays, prebiotics are the matter of interest, because of stimulating the growth and activity of beneficial enteric bacteria (probiotic) and their antimicrobial and antitumor characteristics. The aim of this research is to study the effect of prebiotic Chitosan on the growth of probiotic bacteria and their antimicrobial effect. Materials and Methods: This research was done in 2010 in order to study of the effect of prebiotic chitosan on the growth of probiotic bacteria Lactobacillus acidophilus PTCC 1643 and Lactobacillus casei PTCC 1608 by using of drawing growth curve of these bacteria in the presence of different chitosan concentrations, also, the effect of this prebiotic on antimicrobial properties of probiotic bacteria was investigated against Escherichia coli by using of overlay method and blank disk method. Results: According to the test results, the growth of two probiotic bacteria were increased in the presence of chitosan and the most effective concentration of prebiotic chitosan was achieved, 6.5 (mg/mL).Antimicrobial effects of probiotic bacteria were increased in the presence of chitosan against E.coli especially Entrohaemoragic E. coli in comparison with the time that probiotic bacteria were used alone. Conclusions: According to the results of this study, prebiotic chitosan, due to increasing effect on the growth and antimicrobial characteristic of probiotic lactobacillus, can be a proper candidate for effective symbiotic compound against pathogenic bacteria