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
Page: 1 - 8
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
Virulence and characteristics of a new nucleopolyhedrovirus strain of Dendrolimus kikuchii (Lepidoptera: Lasiocampidae)
Miao Miao Yang1,2,6, Meng Lou Li1, Yu Zhu Wang2, Liang Jian Qu2, Ke Yue Huai3, Xue Wen Nie4, Lu Qin Qiao5, Jin Ying Ding6 and Yong An Zhang2*
1Forestry Entomology Laboratory of Academic Forestry, Northwest Agriculture and Forest University, Yangling 712100 China.
2The Key Laboratory of Forest Protection, State Forestry Administration of China, Research Institute of Forest Ecology, Environment and Protection, Chinese Academy of Forestry, Beijing 100091 China.
3Forestry Research Institute of Yunnan, Yunnan 650000 China.
4Forest Protection Station Mile County of Yunnan, Yunnan 652300 China.
5College of Plant Protection, Shandong Agricultural University, Tai’an 271018 China.
6Ningxia agricultural school, Yinchuan 750000 China.
Accepted 19 January, 2019
Abstract
In present study, a nucleopolyhedrovirus was isolated from the infected larvae of Dendrolimus kikuchii, which is a serious pest for a variety of conifers in China. Ultrastructural observation revealed that this virus is a multiple-nucleocapsid nucleopolyhedrovirus (MNPV), which was encapsulated within the envelope of each virion. Based on the morphological characteristics, it was identified as a new virus and named as DkNPV. It exhibited high potential as a biocontrol agent to protect the forest because of the high virulence against the third-instar larvae of D. kikuchii. The virus passage in the host after 4 generations, toxicity and ultrastructural morphology were stable.
Key words: Dendrolimus kikuchii, multiple-nucleocapsid nucleopolyhedrovirus, Dendrolimus Kikuchii Matsumura nuclear polyhedrosis virus (DkNPV), virulence, ultrastructure, biological control.
Yu Zhu Wang, Meng Lou Li, Lu Qin Qiao, Liang Jian Qu, Ke Yue Huai, Xue Wen Nie, Miao Miao Yang, Jin Ying Ding and Yong An Zhang*
Page: 1 - 5
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,
Page: 1 - 7
Research Article
Advanced Journal of Microbiology Research ISSN 2241-9837 Vol. 13 (3), pp. 001-009, March, 2019. © International Scholars Journals
Full Length Research Paper
Isolation and characterization of a psychrophilic bacterium producing cold active lactose hydrolyzing enzyme from soil of Mt. Himalaya in Nepal
E. S. Nam1, Y. H. Kim2, K. H. Shon2, and J. K. Ahn2*
1Department of Chemical and Biomolecular Engineering, Sogang University, Seoul 121-742, Republic of Korea.
2Department of Agricultural Sciences, Korea National Open University, Seoul 110-791, Republic of Korea.
Accepted 18 February, 2019
Abstract
Psychrophilic bacteria, which grew on lactose as a carbon source, were isolated from soil of Island Peak area at Mt. Himalaya in Nepal, and identified. 148 bacterial isolates were isolated via X-gal hydrolysis on plate. Among these, three isolates, referred to as KNOUC 401, 402 and 403, displayed good cold-adapted growth and activity for hydrolysis of o-nitrophenyl- -D-galactopyranoside (ONPG) and lactose in cell free extracts. Strain KNOUC403 showing negative activity in -hemolysis was selected and identified. The strain was gram-positive bacilli, non-motile, catalase-positive and aerobic. Optimum growth was done at 20°C and pH 6.5~6.8. Anteiso-C15:0 (68.14%) was predominant in the fatty acid composition of cell. The physiological and biochemical properties, cellular fatty acid composition and sequence of 16S rDNA, suggest that strain KNOUC403 indicate a taxonomic affiliation to Arthrobacter psychrolactophilus. The optimal conditions for ONPG hydrolysis of cell free extracts from the strain were 15°C and pH 6.0, and the enzyme was stable at 4°C for 42 h. Zymogram assay of cell free extract from the strain in nondenaturing polyacrylamide gel showed a distinct band of X-gal hydrolysis.
Key words: Psychrophilic bacteria, Arthrobacter psychrolactophilus, cold-active lactose hydrolyzing enzyme, Mt. Himalaya.
Y. H. Kim, K. H. Shon and J. K. Ahn*, E. S. Nam
Page: 1 - 9
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
Bacteriological study of vaginal discharge of pregnant women using Gram stain smear and culture
Manigeh Mehdinejad1*, Azar Dokht Khosravi1,2, Hamideh Yazdizadeh3 and Porandokht Afshari3
1Department of Microbiology, School of Medicine, Ahvaz Jundishapur University of Medical Sciences (AJUMS), Ahvaz, Iran.
2Infectious and Tropical Diseases Research Center, Ahvaz Jundishapur University of Medical Sciences (AJUMS), Ahvaz, Iran.
3School of Nursing and Midwifery, Ahvaz Jundishapur University of Medical Sciences (AJUMS), Ahvaz, Iran.
Accepted 10 January, 2019
Abstract
Bacterial vaginosis is caused by an imbalance of the organisms that naturally exist in the vagina. The importance of bacterial vaginosis with respect to pregnant women’s health is emphasized by the association between bacterial vaginosis and adverse outcome of pregnancy. The aim of present study was to evaluate the direct smear microscopy and culture for determination of bacteria from vaginal discharge of pregnant women. In total, 240 vaginal swabs were collected from 120 pregnant women and were screened for bacterial population. For each patient one swab was used for smear preparation and Gram staining and the second swab was used for cultivation. The prepared Gram-stained smears were observed for various morphotypes. Each morphotype was quantified on a scale from 0 to 4 and weighed to yield a score of 0 to 10, as per Nugent’s system. The bacteria grown in preliminary culture media were identified using standard identification tests. The majority of isolated bacteria in culture were Diphtheroid, Lactobacillus spp., Coagulase-negative Staphylococci and yeast. In Gram-stained smears, 78 (65%) Gram positive rods and 54 (45%) Gram positive cocci were detected. According to Nugent’s criteria, 64 cases (53.33%) were classified as having normal vaginal flora, 45 (37.5%) intermediate flora and 11 cases (9.2%) having bacterial vaginosis. The prevalence of bacterial vaginosis is not very high. However we recommend the regular screening of women with Gram stain method using Nugent’s criteria which is reliable, easy to perform and well suited for the routine clinical laboratory.
Key words: Vaginal discharge, bacterial vaginosis, Nugent’s criteria, Gram stain, culture.
Manigeh Mehdinejad*, Azar Dokht Khosravi, Hamideh Yazdizadeh and Porandokht Afshari
Page: 1 - 5
Research Article
Advanced Journal of Microbiology Research ISSN 2241-9837 Vol. 13 (3), pp. 001-004, March, 2019. © International Scholars Journals
Full Length Research Paper
Prevalence and antimicrobial resistance profiles of Listeria monocytogenes in spontaneous abortions in humans
Lida Lotfollahi1,2*, Jamileh Nowrouzi3, Gholamreza Irajian1, Faramarz Masjedian1, Bahram Kazemi4, Laleh Eslamian5, Arash Falahat6 and Maryam Ramez1
1Department of Microbiology, School of Medicine, Tehran University of Medical Science, Tehran, Iran.
2Department of Microbiology, School of Medicine, Urmia University of Medical Science, Urmia, Iran.
3Department of Biology, Islamic Azad University, North Tehran Branch, Tehran, Iran.
4Chronic Lymphocytic Leukemia (Cll) and Molecular Biology Research Center, School of Medicine, Shahid Beheshti
University of Medical Science, Tehran, Iran.
5Department of Gynecology, Shariati Hospital, Tehran, Iran.
6Department of Cardiology, Shariati Hospital, Tehran, Iran.
Accepted 09 February, 2019
Abstract
Listeria monocytogenes is a causative agent of listeriosis. Clinical manifestation of invasive listeriosis is usually sever and include sepsis and meningoencephalitis. Uterian infection in listeriosis depend on gestational age varies from preterm labour, delivery of infected neonate to abortion. The present study investigated the incidence and antibiograms of the organism in clinical samples were collected from women with spontaneous abortions in Iran. Clinical samples were collected from patients with spontaneous abortions hospitalized in Shariati hospital in Tehran during December 2009 and November 2010. Antibiogram was done by disk-agar method. L. monocytogenes was isolated from 9 of 100 samples. Out of 9 isolates of L. monocytogenes 3 (16.66%), 0 (0%), 1 (4%), 3 (12%) and 2 (8%) were isolated from placental tissue, blood, urine, vaginal and rectal swabs respectively. Resistance to Penicillin G had the highest rate. Because of high incidence of L. monocytogenes in this study, in women with history of abortions or bad obstetric history, diagnosis procedures for detection of L. monocytogenes and on time treatment is recommended additionally because of high resistance rate of bacteria to Penicillin G in this study, antibacterial susceptibility before initiation of treatment is recommended.
Key words: Listeria monocytogenes, spontaneous abortion, antibiotic resistance.
Faramarz Masjedian, Jamileh Nowrouzi, Gholamreza Irajian, Bahram Kazemi, Arash Falahat and Maryam Ramez, Laleh Eslamian, Lida Lotfollahi*
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