Influence of some chemicals and solvents on the lytic activity and the adsorption of bacteriophages on Pectobacterium carotovoroum Subsp. carotovorum

Recently, bacteriophages have been used to control hazardous bacterial soft rot disease on crops. However, agricultural plants are frequently treated with different chemicals (fertilizers, pesticides and solvents), so we assessed the effect of some commonly used chemicals and solvents on the lytic activity of tested bacteriophages and their adsorption potential. This study reports the isolation of three specific phages against the Pectobacterium carotovorum subsp. carotovorum DSM 30170 strain, designated as ?PC1, ?PC2 and ?PC3, then partially characterized using electron microscopy and genome size. The 3 isolated phages belong to the Myoviridae family. The results obtained were based on the plaque-forming unit observed after incubation. By increasing the chemical concentrations (from 0.1 to 0.5 mM), calcium chloride (CaCl2) and potassium chloride (KCl) showed a significant increase in the lytic activity of the phages. Copper sulphate (CuSO4) and copper chloride (CuCl2) showed a substantial decrease in the activity of ?PC3; however, such a decrease was insignificant for ?PC1 and ?PC2. By increasing the solvent concentrations (from 30 % v/v to 70 % v/v), propanol, ethanol and methanol showed a significant decrease in the count of the three isolated phages, ?PC1, ?PC2 and ?PC3, compared to the control. Chloroform was the only solvent that did not reduce the phage titer. Our findings offer significant information for developing a strategy to combat the P. carotovorum subsp. carotovorum caused bacterial soft rot disease. avoiding copper compounds and alcoholic solvents such as propanol, ethanol and methanol in plots where phages are applied seems advisable

Detection of Ralstonia solanacearum phylotype II, sequevar 1 in seasonal weed plants associated with potato cultivations in Egypt

تم أخذ عينات عشوائية من نباتات الحشائش من حقول البطاطس المختلفة الموجودة  ببعض  القرى المصرية وفحصها لمعرفة  مدى وجود المسبب المرضي Ralstonia solanacearum  بها .  كان إجمالي عدد العينات (1609 ) عينة   على مدار موسمين(2017 /2018 ( و (2018/2019( .  تضمنت هذه الحشائش حوالى (50) نوع نباتي تابعين لحوالي (20) عائلة نباتية، اخذت هذه العينات من حقول البطاطس الموجودة ببعض القرى  التابعة لمحافظات القليوبية ،البحيرة ، الجيزة ، الغربية ، الاسماعيلية والمنوفية (دجوى، السعدنى ، الرفاعى ، كفر يعقوب ، أبوصوير وطاليا) على الترتيب. تم عزل المسبب المرضى من (272) عينه من الحشائش وتضمن هذا العدد  حوالى (25) نوع نباتي  تابعين ل (13) عائلة نباتية. تم تجميع هذه الحشائش على عمر 70 يوم من زراعة البطاطس ولم تكن الحشائش بها أي أعراض تدل على اصابتها بالبكتريا المسببة لمرض العفن البنى في البطاطس. بصفة عامة كان معدل اصابة هذه الحشائش بالبكتريا المسببة لمرض العفن البنى قليلا اذ وصل الى حوالى (16.9%). انتمت جميع عزلات ال R. solanacearum المعزولة من الحشائش الى phylotype II, sequevar 1 (race 3, biovar 3). أوضحت النتائج ان أعلى نسبة إصابة للحشائش بالبكتريا كانت في محافظتي الغربية والقليوبية حيث بلغت (44.7) و (31.7%) على الترتيب تلاهم في الاصابة محافظة البحيرة حيث بلغت نسبة الاصابة الى (16,1%)  بينما سجلت محافظة المنوفية اقل نسبة إصابة (11,5%). علاوة على ذلك فقد سجلت كلا من محافظتي الجيزة والاسماعيلية تقريبا نفس نسبة الاصابة في الحشائش اذ بلغت (12,7و13,9% ) على الترتيب. كانت الحشائش الشتوية الحولية هي الأكثر إصابة وتضمنت (11 ) نوعاً Chenopodium album L.,  Chenopodium mural L., Cichorium pamilum, Malva parviflora L., Medicago polymorpha L., Rumex dentatus L., Sisymbrium irio L., Sonchus oleraceus L. and  Urtica urens L.. تلاهم في الاصابة  الحشائش الصيفية الحولية والتي شملت (7) انواع من الحشائش المختلفة :  Arachis hypogaea, Conyza aegyptiaca L., Cyperus difformis L., Dactyloctenium aegyptium L, Polypogon monspeliensis L.,Portulaca oleracea L.and Solanum nigrum L. بينما تضمنت الحشائش المعمرة على (4) أنواع من الحشائش: Convolvulus arvensis L., Cyperus rotundus L., Cynodon dactylon L., Dichanthium annulatum. علاوة على ذلك فقد اشتملت الحشائش ذات الحولين على (2) فقط من الحشائش وهما: Centaurea calcitrapa L.and Beta vulgaris L تشير النتائج إلى أن الحشائش الخالية من الأعراض قد تكون مصدرًا خطيرًا للإصابات الكامنة لكلا من الحشائش أو محصول البطاطس المعد للتصدير ويمكن اعتبارها من عوائل بكتيريا ال R. solanacearum  Weed plants were randomly sampled from different potato fields in some Egyptian villages and were examined for the presence of Ralstonia solanacearum. A total of (1609) plants were sampled over two year's period (2017/2018 and 2018/2019). These weeds were found belonging to almost (50) species affiliated to (20) families associated more or less with the potato fields near Al-Kalubeiah, El-Behira, El-Giza, El-Gharbeya, El-Ismailia and El-Menofiya governorates at different village (Digwa, El-Saadany, Al-Rifai, Kafr-Yaqoub, Abu Sawyer and Talia, respectively). The pathogen was successfully recovered from the crown area of 272 plant weeds belonging to 25 plant species of 13 families. The weeds in concern, 70 days after planting potato, were found latently infected and mostly symptomless at the time of sampling. The rates of positive isolation from these weeds were generally low, and account for 16.9%. All isolates of R. solanacearum from weeds were confirmed as phylotype II, sequevar 1 (race 3, biovar 2) via PCR. Data revealed that, the highest infection percentage of weed plants were shown from El-Gharbeya and Al-Kalubeiah, governorates (44.7 and 31.7 % respectively) followed by El-Behira governorate (16.1%), whereas the lowest percentage (11.5%) was observed in El-Menofiya governorate. On the other hand, both El-Giza and El-Ismailia governorates showed almost similar percentage of infected weeds (12.7 and 13.9% respectively). The winter annual weeds were the most affected weeds and included 11 different species of weeds (e.g. Amaranthus ascendens Lois, Amaranthus cruentus, Chenopodium album and Chenopodium mural) followed by the summer annual weeds that included 7 different species (e.g. Portulaca oleracea L. and Solanum nigrum L.). While the perennial weeds included 4 species (e.g. Convolvulus arvensis and Dicanthium annulatum), the biennial, however, weeds included only two species of infected weeds (Beta vulgaris L. and Centaurea calcitrapa L.). The results denoting that symptomless weeds might be a serious masked source of latent infection for either weeds or exported potato crop and it may be considered as an attractive overwintering hosts of R. solanacearum