ISSN 2736-1756
Research Article
Advanced Journal of Microbiology Research ISSN 2241-9837 Vol. 13 (3), pp. 001-008, March, 2019. © International Scholars Journals
Full Length Research Paper
Influence of growth conditions and nutritional requirements on the production of hydrogen peroxide by lactic acid bacteria
Abimbola Enitan1*, Josiah Adeyemo1 and S. T. Ogunbanwo2
1Durban University of Technology, P. O. Box 1334, Durban, 4000, South Africa.
2Department of Botany and Microbiology, University of Ibadan, Oyo State, Nigeria.
Accepted 10 February, 2019
Abstract
Lactic acid bacteria (LAB) were isolated from raw and fermented milk samples. They were evaluated for hydrogen peroxide (H2O2) production. Sixty–three strains of LAB belonging to the genera Lactobacillus, Leuconostoc, Lactococcus and Streptococcus were isolated and all the isolates produce H2O2 with Lactococcus lactis having the highest yield of 0.4279 mg/L in de Mann Rogosa Sharpe (MRS) broth. Among the high–level H2O2-producing strains are Lactobacillus bulgaricus, Lactobacillus casei, L. lactis and Streptococcus thermophiles. They were subsequently selected and their culture supernatants were evaluated at different temperatures, pH values and using different carbon and nitrogen sources. The highest quantity of H2O2 (0.6517 mg/L) was produced at 37°C by S. thermophilus, while L. casei produced the lowest quantity of 0.1132 mg/L at 40°C . S. thermophilus produced the highest quantity of 0.5912 mg/L at pH 5.5, while the lowest quantity of 0.1042 mg/L was produced at pH 7. L. bulgaricus produced the highest concentration of0.6512 mg/L when galactose was used as carbon source and lowest quantity of 0.0210 mg/L was produced by L. lactis in basal medium containing sorbitol as carbon source. L. casei produced both the highest and lowest quantities of 0.1895 and 0.0207 mg/L of H2O2 in medium supplemented with yeast extract and ammonium sulphate as nitrogen sources respectively. The antimicrobial activity of the culture supernatants against Escherichia coli K12, Staphylococcus aureus and Candida albicans using agar well diffusion assay was evaluated. Cell-free supernatant by L. bulgaricus had the highest inhibitory activity against E. coli K12 with 21 mm zone of inhibition and against S. aureus with 15 mm zone of inhibition but showed no antagonistic activity against C. albicans. The study revealed that lactic acid bacteria isolated from raw and fermented milk in South-West Nigeria are capable of producing hydrogen peroxide which has antagonistic effect on pathogenic organisms, thus, may be promising sources of preservative that may in future be applied to food.
Key words: Hydrogen peroxide, growth conditions, nutrient utilization, antagonistic activity, lactic acid bacteria (LAB).
Abimbola Enitan*, Josiah Adeyemo and S. T. Ogunbanwo
Research Article
Characterization of biofilm formation by Salmonella enterica Serovar Pullorum strains
Advanced Journal of Microbiology Research ISSN 2241-9837 Vol. 13 (3), pp. 001-010, March, 2019. © International Scholars Journals
Full Length Research Paper
Characterization of biofilm formation by Salmonella enterica Serovar Pullorum strains
Yan Lu1, Hongyan Dong1, Sujuan Chen1, Yiping Chen2, Daxin Peng1* and Xiufan Liu1
1College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu, 225009, P. R. China.
2China Animal Health and Epidemiology Center, Qingdao, 266032, P. R. China.
Accepted 19 January, 2019
Abstract
Salmonella enterica Serovar Pullorum causes acute or persistent infection in chickens, resulting in significant economic losses. The objective of this study was to evaluate the biofilm-forming ability of S. enterica Serovar Pullorum strains and association with the pathogenicity. A total of 62 S. enterica Serovar Pullorum isolates were measured for biofilm formation by crystal violet staining. Thirty-nine out of 62 strains were found to produce biofilm which were further confirmed by observation under light microscopy, field emission scanning electron microscopy. Analysis of the major components for biofilm formation showed that bacterial colonies were smooth phenotype and the architecture of biofilm was composed of exopolysaccharides and curli other than cellulose. In addition, animal experiments were performed to determine the 50% lethal doses (LD50) of four S. enterica Serovar Pullorum isolates with or without biofilm-producing ability. Although the virulence of S. enterica Serovar Pullorum strains was independent of the ability of biofilm formation, prior growth as a biofilm for a biofilm producer of S. enterica Serovar Pullorum lead to enhanced virulence in chickens. The results suggested that biofilm may be one of the important virulence factors for S. enterica Serovar Pullorum infection.
Key words: Salmonella enterica Serovar Pullorum, biofilm, curli, virulence.
Daxin Peng* and Xiufan Liu, Yiping Chen, Hongyan Dong, Yan Lu, Sujuan Chen
Research Article
Advanced Journal of Microbiology Research ISSN 2241-9837 Vol. 13 (3), pp. 001-007, March, 2019. © International Scholars Journals
Full Length Research Paper
Determination of insecticidal toxicity of three species of entomopathogenic spore -forming bacterial isolates against Tenebrio molitor L. (Coleoptera: Tenebrionidae)
N. Du Rand and M. D. Laing
Department of Plant Pathology, University of KwaZulu-Natal, Private Bag X01, Scottsville 3209, Pietermaritzburg, Republic of South Africa.
Accepted 10 January, 2019
Abstract
Bioassays were conducted using larvae of mealworms, Tenebrio molitor, to determine lethal concentration for five entomopathogenic strains of spore-forming bacteria. Lethal concentration was determined by feeding T. molitor larvae cabbage discs dipped in whole cell cultures of these five strains of bacteria. The strains of bacteria were isolates of Bacillus cereus, Bacillus thuringiensis and Brevibacillus laterosporus. An isolate of B. cereus required the highest concentration of viable spores (8.531 x 107 spores ml-1) to achieve its LC50, whereas an isolate of B. laterosporus required the lowest concentration of viable spores (3.388 x 106 spores ml-1) to achieve LC50.
Key words: Mealworms, spore-forming bacteria, bioassays.
N. Du R, M. D. Laing,
Research Article
Screening of the PGPR strains compatible with Cajanus cajan and used as biofertilizer
Advanced Journal of Microbiology Research ISSN 2241-9837 Vol. 13 (3), pp. 001-005, March, 2019. © International Scholars Journals
Full Length Research Paper
Screening of the PGPR strains compatible with Cajanus cajan and used as biofertilizer
M. Usha Rani1, Arundhathi2 and Gopal Reddy3
1Principal Investigator, Department of Science and Technology (DST), "Women Scientists Scheme WOS, A, JNTUK, Kakinada, India.
2Department of Botany, Andhra University, Visakhapatnam, India.
3Department of Microbiology, Osmania University, Hyderabad, India.
Accepted 10 January, 2019
Abstract
Plant growth promoting rhizobacteria (PGPR) are beneficial bacteria that colonize plant roots and enhance plant growth by a wide variety of mechanisms. The use of PGPR is steadily increasing in agriculture and offers an attractive way to replace chemical fertilizers and pesticides. Here, we have isolated and characterized PGPR traits from the rhizosphere soil of pigeon pea and tested for the growth enhancement of pigeon pea. Rhizosphere soils were collected from different areas of Samalkot, Pithapuram, Peddapuram and Kakinada in India. A total of 65 isolates have been identified and characterized for their morphological, cultural, staining and biochemical characteristics, of which 35 isolates have been selected for further screening of PGPR traits. Sixteen isolates were successfully characterized for the PGPR traits like indole acetic acid (IAA) production, phosphorus solubilization and 1-aminocyclopropane-1- carboxylate (ACC) deaminase. Among the sixteen isolates, seven were found to be high IAA producing. Six were found to be efficient phosphate solubilizers, two were shown to be promising in both IAA production, phosphate solubilization and mineralizing capacity. These isolates showed growth promotion in pigeon pea for seedling emergence, increase of shoot length, root length, dry matter production, nodule number and nodule mass. Furthermore, PGPR isolates remarkably increased seed germination of pigeon pea. The two promising isolates were identified for 16sRNA sequencing and found to be Bacillus cereus and Enterobacter cancerogens.
Key words: Indole acetic acid (IAA), plant growth promoting rhizobacteria (PGPR), phosphorus solubilization, 1-aminocyclopropane-1-carboxylate (ACC) deaminase, polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP), seed germination.
Arundhathi and Gopal Reddy, M. Usha Rani
Research Article
Advanced Journal of Microbiology Research ISSN 2241-9837 Vol. 13 (3), pp. 001-005, March, 2019. © International Scholars Journals
Full Length Research Paper
Characteristics of the secretory expression of pectate lyase A from Aspergillus nidulans in Escherichia coli
Zhihua Han1,2, Qingxin Zhao1,3*, Huanli Wang1,3 and Yijun Kang1,3
1Jiangsu Provincial Key Laboratory of Coastal Wetland Bioresource and Environmental Protection, Yancheng Teachers University, Yancheng City, Jiangsu Province 224002, China.
2Nanjing Institute of Environmental Sciences of State Environmental Protection Administration, No. 8 Jiangwangmiao Street, Nanjing, Jiangsu 210042, China.
3College of Life Science and Biotechnology, Yancheng Teachers University, Xiwang Road, Yancheng, Jiangsu 224002, China.
Accepted 11 February, 2019
Abstract
Pectate lyases from Aspergillus spp. are a major kind of industrial pectinases, can improve the surface properties of natural fibers and have promising applications in medicine, food, textile and other industries. Pectate lyases catalyze the eliminative cleavage of de-esterified pectin, which is a major component of the primary cell walls of many higher plants. The Pectate lyase A (PelA) gene without an N-terminal signal peptide sequence from Aspergillus nidulans was recombinantly expressed using Escherichia coli as the host strain and pET-20b(+) as expression vector with a pelB N -terminal signal pepetide. PelA biosynthesis reached the maximum production field (450 U ml-1 medium) at 0.5 mM IPTG, 37°C, 200 rpm, for 2 h and the expressed PelA primarily appeared in extracellular medium. Calcium ion had a more obvious promotion than glycine and SDS to the extracellular enzyme fields, and the C-terminal sequence of Pel A might have an important effect on the transportation through the outer-membrane of E. coli. The time (2h) of reaching the maximum enzyme at 37°C implied that the PelA expression was very significant to pectate lyase industrial production.
Key words: Characteristics, extracellular expression, pectate lyase A, Aspergillus nidulans, Escherichia coli.
Zhihua Han, Huanli Wang and Yijun Kang, Qingxin Zhao*
Research Article
Advanced Journal of Microbiology Research ISSN 2241-9837 Vol. 13 (3), pp. 001-008, March, 2019. © International Scholars Journals
Full Length Research Paper
Effect of oligosaccharides and isoflavones aglycones in defatted soy meal fermented by Lactobacillus paracasei and Bifidobacterium longum
T. R. Chen1*, Q. K. Wei2, and Z. X. Chi1
1Department of Food Science, National Chia-Yi University, No.300 Syuefu Rd., Chia-Yi, 60004, Taiwan, Republic of China.
2Department of Food Science and Technolgoy, National Taitung Junior College, No.889, Jhengci North Road, Taitung, 95045 Taiwan, Republic of China.
Accepted 17 February, 2019
Abstract
The study determined bacterial population, pH value, oligosaccharides and isoflavone in defatted soy meal fermented by Lactobacillus paracasei and Bifidobacterium longum at 37°C for 48 h. B. longum and L. paracasei fermented in defatted soy meal has significantly increased the maximum bacterial population over 9.6 log CFU/h and reduced pH to 4.9. Furthermore, content of oligosaccharides, including sucrose, raffinose and stachyose, in FDSM were significantly reduced by L. paracasei (97.7, 98.3 and 98.5%) and B. longum (98.0, 97.5 and 86.3%, P<0.05). Isoflavone aglycones concentration was significantly increased to 60% for B. longum and was higher than 52% for L. paracasei (P<0.05). Daidzein and genistein increased concentration to 28-folds and 14.4 to 15.6-folds, respectively, compared to unfermented defatted soy meal.
Key words: Oligosaccharides, isoflavones, defatted soy meal, Lactobacillus, Bifidobacterium.
T. R. Chen*, Q. K. Wei and Z. X. Chi