New Culture Media Using The Pericarp Layer of Citrus Fruits For Cultivating Bacteria and Fungi
Samia Ahmed Gumaa , Mohamed Taha Shigidi, Ahmed Mohamed Abd Alathem
كلية الطب البيطري-جامعة الخرطوم · السودان
Powder of pericarp layers fromorange and grape fruit wereused as a source of nutrients for culturing some species of bacteria andfungi. Nine reference strains and one bacterium isolates and nineisolates of fungi, identified to species level were tested for theirgrowth ability on orange pericarp media. Orange pericrp powder withagar and NaCl (type1), orange pericarp powder with agar, NaCl andpotassium nitrate (type2), and orange pericarp powder with agar,NaCl and peptone water (type 3) were used to test bacterial growth.Whereas orange pericarp media consisting of pericarp powder withagar and peptone water (type A) , pericarp powder with agar, peptonewater and potassium nitrate (type B), pericarp powder with agar,peptone water and vitamins (B1, B6 and B12) ( type C) and type Cmedium with potassium nitrate (typeD) were used to test fungalgrowth.Escherichia coli, Pseudomonas aeruginosa Klebsiella pneumoniaeStaphylococcus aureus, Salmonella typhimurium, Shigella flexneri,Proteus mirabilis, Bacillus subtilis, Enterococcus feacalis andSterptococcus agalactiaegrew well on pericarp medium type3.Whereas only E.coli and K.pneumoniae grew on pericarp mediatype 1 and 2. Fastidious bacterium namely: Strept. pyogenesfailed tovgrow in all types of media. Differences in apperance and color of thecolonies were noted for some tested bacterial species when grown ongrape fruit pericarp media comparedto orange pericarp media.When comparedwith MacConkey’s and blood agar, orangePericarp medium type 3 was found to be a non inhibitory medium,cheap and very easy to prepare. There was low risk of contaminationduring pouring and sterilization procedures, compared to blood agar.Special growth characteristics of some bacterial species were moreconspicuous on this medium, for example; K.peumoniaeproducedvery mucoid colonies; swarming growth was very marked withPr.mirabilisand Ps.aeruginosa produced visible diffused pigments.All Aspergillus species (A.niger, A.terreus, A.flavus, andA.fumigatus), Trichophyton species(T.mentagrophytes, T.verrucosumandT.schoenleinii) andMicrosporum canisgrew well on orangepericarp media, but Microsporum audouinii failed to grow.T.mentagrophytes grew on all types of orange pericarp media,except type A. It produced different colonial morphology; one of thesecolonies had special grey volcano/cut tree appearance. Growth of M.canis, T.verrucosum and T.schoenleiniiwas slow and scanty onorange pericarp media compared to that on Sabouraud dextrose agar.Growth of Aspergillus specieswas faster on pericarp media than onviSabouraud dextrose agar, but the amount of growth was comparableon both media. Rate and quantity of growth ofT.mentagrophyteswerecomparable on both, pericarp media and Sabouraud dextrose agar.There were variations in the appearance ofT.mentagrophytescolonieson pericarp media; not noted on Sabouraud dextrose agar. On pericarpmedia the colonies were larger and granular and some have a volcano– shapes. It appears that pericarp media can be used as non inhibitorymedia for culturing some bacterial and fungal species