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B Mukoye*, BC Mangeni, RK Leitich, DW Wosula, DO Omayio, PA Nyamwamu, W Arinaitwe, S Winter, MM Abang and HK Were

In western Kenya, groundnuts (Arachis hypogaea L.) is one of the major legumes where it is not only the principal source of protein but also a major source of small-holder cash income. However, groundnut production has continued to decline with farmers realizing less than 50% of the yield potential. Viral diseases play a great role in yield reduction. Cowpea mild mottle virus (CPMMV) has been reported to be one of the viruses infecting groundnuts but its status in western Kenya was not known. Therefore this study sought to establish whether the virus was already infecting groundnuts in this region. Two surveys were conducted in seven major groundnut growing Counties of western Kenya; Bungoma, Busia, Vihiga, Siaya, Migori, Nandi and Homabay, basing on various Agro-ecological zones (AEZs). Leafy samples were collected and tested by DAS-ELISA. Indicator plants were mechanically inoculated with CPMMV from positive samples and symptoms observed. The disease was found to be widespread in all the AEZs surveyed with high incidence at farm levels. Most farmers were found to use uncertified seed. ELISA tests confirmed the presence of CPMMV in the leafy samples collected from the farms. The virus induced varied symptoms on indicator plants tested. All the indicator plant used were major legumes grown in western Kenya and were found to be susceptible to CPMMV. This implies that CPMMV is a serious threat to legume production in western Kenya

Isolation and Characterization of Bacteriocin-Producing Lactic Acid Bacteria against Indicator Organisms

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Nagwa B Elhag*, El Rakha B Babiker and Ahmed A Mahdi

In the last recent years, bacteriocins produced by lactic acid bacteria (LAB) have received a considerable attention to be used as biopreservatives in different fields of food industry. LAB was isolated from Sudanese fresh sausages, intestines of different animals, saliva, cheese and cucumber in de Man Regosa and Sharp medium. In this study the antimicrobial effect of LAB producing-bacteriocins against Staphylococcus aureus ATCC 2818, Bacillus cereus, and Escherichia coli ATCC 29522 was studied. The agar well diffusion assay (AWDA) was followed to determine the antimicrobial effect. Characterization of bacteriocin produced by LAB was conducted by exposing bacteriocins to different heat treatment at 40, 60, 80, 100, and 121OC for 0, 30, 60 or 90 minutes and after a week in a water bath set up at 37 OC, and adjusted to different pH levels at 2, 4, 6, 8, 10 and 12. Sensitivity to enzymes was assayed by treatment with α-amylase and the proteolytic enzyme pepsin. Only 16 LAB isolates of 30 produced clear inhibition zones. Only 3 LAB isolates of 16 exhibited the strongest performance against the indicator organisms. These LAB isolates were identified as Enterococcus faecalis, Pediococcus pentosaceus, and Lactobacillus murinus. Characterization of bacteriocins obtained revealed that these substances were found to be stable after heat treatment, at low pH and at pH 6-8. The proteinaceous nature of bacteriocins was completely lost after treatment with the proteolytic enzyme pepsin. Sudanese products of animal sources may be a rich source for bacteriocins-producing LAB which can be used as bio-preservatives

Comparative assessment of antimicrobial activity of five extract of P. longum and P. nigrum against B. brevis, P. thailandensis, E. aerogenes and B. anthracis

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Somesh Mehra*, Apurwa Dubey, Jose Mathew and Manish Mehra

In the present study the four candidate microbes B. brevis, P. thailandensis, E. aerogenes and B. anthracis were isolated from soils samples and were identified through various biochemical tests. The PCR amplification and sequencing of 16s rRNA gene was also performed for accurate identification of candidate microbes and showed up amplicon size of 718bp ,453bp, 581bp & 499bp respectively on agarose gel electrophoresis and sequencing. The antimicrobial activities of five different extract of P. longum and P. nigrum fruits have been investigated on the candidate microbes. P. longum & P. nigrum showed maximum antimicrobial activity against E. aerogenes and B. brevis, respectively in methanolic and isopropanolic extracts form correspondingly. P. thailandensis and B. anthracis were highest inhibited by P. longum in methanolic & isopropanolic extract form respectively, while by P. nigrum in isopropanolic extract form. In general, Piper longum demonstrated highest antimicrobial activity in methanolic extract form while P. nigrum in isopropanolic extracts form. This study emphasize that Piper longum and P. nigrum are enormously vital as natural antimicrobial agent or as it adjuvant and in microbiologically secure foods

Diversity of Rhizobium leguminosarum bv. viceae Strains Isolated from Different Schemes in Shendi Area

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Tagelsir Hassan Mohamed Ahmad* and Mohamed Saifelden Abdelmageed

An attempt has been made to evaluate the diversity of sixteen Rhizobium leguminosarum bv. viceae strains isolated from different schemes in Shendi area. Morphological and cultural characteristics were performed viz: colony morphology, Gram staining and motility. Biochemical and physiological tests include acid - base production, oxidase and catalast tests were carried out. The effects of antibiotics on the growth of Rhizobium strains on YEMA media were tested using measurement of diameters of the growth inhibition zones. Growth of pure rhizobial isolates on (YEM) medium having variable range of pH (5.5 to 8.5) and different concentrations of NaCl (0.5 - 6.6 %) were recorded. The genetic diversity of the eleven studied strains were examined and screened for the polymorphism and were amplified using two different RAPD primers (OPC9 and OPY14). The isolates studied were motile, gram negative and rod shaped and catalase and oxidase positive bacteria. Regardless the location of isolation. Rhizobium strains tested showed significant differences (P < 0.05) in their sensitivity to the antibiotics. Strain SHUOS1F34, SHUMAF6 and SHUGF37 were the most sensitive strains where as strain SHUJ15F2, SHUSSF4 and SHUR2F36 were the most tolerant ones to almost all antibiotics tested. With the exception of strain SHUNOF35, which tolerate high pH values upto 8.5, the growth rate of all strains increased steadily with increasing pH from 5.5 reaching the maximum at pH 6.5 to 7.5 and declined then after to 8.5. In all the tested strains the growth rate decreased with increasing salt concentration from 0.5 upto 6%.The two RAPD primers gave amplification products and they were reproducible. A total of 88 fragments were detected representing 15 different loci with 100% polymorphism. The most relative lines were strains SHUTR2F36 and SHUGO3F42 with 79% similarity. According to the similarity indices, the eleven strains were grouped into four Clusters