Dergiler / EurAsian Journal of BioSciences (elektronik) / 2010 / Sayı: 4
Isolation and characterization of salt-tolerant nitrogen-fixing microorganisms from food
- Sayı
- 2010 · Sayı: 4
- Sayfa
- 33–40
- DOI
- —
Özet
Halofilik mikroorganizmalar halihazirda; ß-karoten, polimerler (polihidroksialkanoatlar ve polisakkaritler), enzimler ve uygun çözgenler gibi bazi biyoteknolojik islemlerde kullanilmaktadir. Ticari önemi göz önünde bulundurularak, gida örnekleri (kaba tuz kristalleri ve ham mango tursusu) halotolerant mikroorganizmalarin izolasyonunda kullanildi. Gida örneklerinden elde edilen iki bakteriyel izolat; stres sartlari altinda hayatta kalma ve artan NaCl (%1 ila %15 w/v), pH (5.0 ila 10.0) ve sicaklik (10 ila 70°C) seviyelerindeki büyüme tepkileri açisindan incelendi. Izolatlar, çubuk seklinde gram-pozitif, tuza dayanikli, halofitik olmayan azot tutucu suslardi. Glukoz, fruktoz, maltoz, sukroz, ksiloz and laktoz gibi farkli sekerler, asit ve gaz üretimini kontrol etmek için kullanildi. Organizmalar, kasein, nisasta ve jelatin gibi substratlari hidrolize etme yetenekleri açisindan incelendi. Bu organizmalar, (i) SM bazal tuz ortaminda ve azotsuz yari-kati LGI ortaminda iyi büyüdüler, (ii) %10-15 tuz konsantrasyonunu tolere ettiler, (iii) D-glukoz, D-fruktoz ve sukrozdan asit ürettiler, (iv) karbon kaynagi olarak gliserol ve sitrik asiti kullandilar ve (v) asidik (pH 4-5) ve alkalin (pH 9- 10) sartlarda hayatta kaldilar. Bu sonuçlar; endüstriyel açidan önemli enzimlerin kaynagi olarak performanslarini gelistirme potansiyeli oldugunu gösterdi. Morfolojik ve biyokimyasal özelliklerine dayali olarak, bu izolatlarin Bacillus cinsine ait oldugu belirlenmistir. Ayrica 16S rRNA'nin kismi dizininden elde edilen sonuçlar, izolat 1 ve 2'nin sirasiyla Bacillus subtilis subsp. subtilis NCIB 3610T (%97,9) ve Bacillus sonorensis NRRL B-23154T (%99,8) ile yakin iliskili oldugunu ortaya çikarmistir.
Abstract
Halophilic microorganisms are already in use for some biotechnological processes, such as commercial production of ß-carotene, polymers (polyhydroxyalkanoates and polysaccharides), enzymes, compatible solutes etc. Considering their commercial importance, food samples (crude salt crystals and raw mango pickle) were used for isolation of halotolerant microorganisms. Two bacterial isolates obtained from food samples were examined for their ability to survive under stressed conditions and their growth response in increasing levels of NaCl (1 to 15% w/v), pH (5.0 to 10.0) and temperature (10 to 70°C). The isolates were rod shaped Gram-positive, salt-tolerant, non-halophilic, nitrogen-fixing strains. Different sugars such as glucose, fructose, maltose, sucrose, xylose and lactose were used to check for acid and gas production. The organisms were studied for their ability to hydrolyse substrates such as casein, starch, gelatin, etc. These organisms (i) grew well in SM basal salt medium and nitrogen-free semi-solid LGI medium (ii) tolerated 10-15% salt concentration (iii) produced acid from D-glucose, D-fructose and sucrose and (iv) utilized glycerol and citrate as carbon source, and v) survived acidic (pH 4-5) and alkaline (pH 9-10) conditions. The results suggested that there is potential to improve their performance as sources of industrially important enzymes. On the basis of morphological attributes and biochemical characteristics the isolates belonged to the genus Bacillus. The results of partial sequencing of 16S rRNA also revealed that the isolates 1 and 2 are closely related to Bacillus subtilis subsp. subtilis NCIB 3610T (97.9% pairwise similarity) and Bacillus sonorensis NRRL B-23154T (99.8% pair-wise similarity) respectively.