Publication: Production of polyhydroxyalkanoate from extreme obligate alkaliphilic strain bacillus marmarensis gmbe 72t ısolated from mushroom compost
Abstract
Geleneksel petrol türevli sentetik plastiklerin çevre üzerinde bir çok zararlı etkileri olması nedeni ile son yıllarda doğal biyobozunur polimerler önemli ölçüde ilgi odağı olmuştur. Özellikle mikrobiyal kaynaklardan üretilen bu polimerler sentetik plastikler ile çok benzer fiziksel özellikler göstermelerinin yanı sıra, doğada parçalandıklarında toksik etkisi olmayan zararsız moleküller oluşturmaktadırlar.Mikroorganizma kaynaklı doğal biyopolimerlerin başında gelen polihidroksialkonatların (PHA) en iyi tanımlanmış türü olan poli-3-hidroksibütirat, biyouyumluluğu ve polipropilen ile benzer özellik göstermesi nedeni ile çeşitli uygulamalar için en çok ilgi odağı olan biyobozunur polimerlerden bir tanesidir. Gram negatif mikroorganizmalar olan Alcaligenes eutophus ve Alcaligenes lotus endüstriyel PHB üretiminde yaygın olarak kullanılan mikroorganizmalardır. Ancak gram negatif bakteriler dış membranlarındaki lipopolisakkarit kısımlarında endotoksin taşıyor olduklarından, gram-pozitif bakteriler medikal uygulamalarda kullanım amaçlı PHB üretimi için daha uygundur. Bu nedenle PHB üretimi için özellikle Bacillus türleri üzerine yoğunlaşılmıştır.Ülkemizde Marmara Bölgesinde bulunan bir mantar çiftliğinden izole edilen ve zorunlu alkalifilik olan Bacillus marmarensis’in genomunda PHB üretimi ile ilgili genleri bulundurması sebebi ile, bu çalışmada B. marmarensis’in PHB üretim kapasitesi incelenmiştir. Elde edilen sonuçlara göre en iyi PHB sentezinin 30°C sıcaklıkta, 1% (v/ v) inokülasyon ile 24 saatte sağlandığı bulunmuştur. 0,3% et özütü ve 0,5% pepton içeren besiyerinde üretimin, sukroz, glukoz, fruktoz ve maltoz ilavesi ile azaldığı, fakat aynı ortama MgSO4 ve KH2PO4 ilavesi ile arttığı görülmüştür. Zorunlu alkalifilik bakteri olması sebebi ile pH etkisi incelendiğinde, ilginç bir şekilde organizmanın ortam pH’sını düşürerek PHB üretimini gerçekleştirdiği ve pH 8,8 de en iyi sentezin gerçekleştiği belirlenmiştir. B. marmarensis tarafından üretilen PHB karakterize edildiğinde, ticari PHB ile kristal yapısının benzer olduğu ve bu nedenle çeşitli prosesler için uygulanabilir olabileceği bulgusuna ulaşılmıştır. Bu çalışma, zorunlu alkalifilik B. marmarensis’ten PHB üretimi ile ilgili gerçekleştirilen ilk çalışmadır.
Since conventional petroleum derived synthetic plastics cause several harmful effects on the environment, in recent years, natural biodegradable polymers have gained a great deal of attention. These polymers, which are especially produced from microbial sources, have similar physical properties to synthetic plastics and they are capable of decomposing into innocuous molecules, which are non-toxic.Poly-3-hydroxybutyrate (PHB), the best-characterized member of microorganism originated Polyhydroxyalkanoates (PHAs), is one of the most attractive biodegradable polymer for several applications due to its biocompatibility and similar properties with polypropylene.Gram-negative microorganisms Alcaligenes eutophus and Alcaligenes lotus are commonly used microorganisms for industrial PHB production. However, since the outer membrane lipolpolysaccharides of those microorganisms include endotoxins, gram-positive bacteria are more convenient for production of PHB to be used in medical applications. Hence, Bacillus species were brought in the center of attraction for PHB production.Since the genes related to PHB production are included in the genome of obligate alkaliphilic Bacillus marmarensis, which was isolated from a mushroom compost in our country in Marmara Region, its PHB production capability was investigated in this thesis. According to the results obtained from experiments, the highest PHB synthesis was achieved at 30°C with 1% inoculation at the end of 24 hr incubation. It was revealed that addition of sucrose, glucose, maltose or fructose to medium supplemented with 0,3% meat extract and 0,5% peptone caused to decrease PHB production , while addition of MgSO4 ve KH2PO4 into the same medium enhanced PHBproduction. When the effect of pH were investigated, although organism is an obligate alkaliphilic Bacillus, it reduced the initial pH in order to produce PHB and the highest PHB synthesis was obtained at initial pH 8,8.Regarding the characterization of PHB produced from B. marmarensis , it was executed that its crystallinity was similar to commercial PHB and thus it can be applicapable for several processes. To our knowledge, this is the first attempt to investigate the production of PHB from obligate alkaliphilic B. marmarensis.
Since conventional petroleum derived synthetic plastics cause several harmful effects on the environment, in recent years, natural biodegradable polymers have gained a great deal of attention. These polymers, which are especially produced from microbial sources, have similar physical properties to synthetic plastics and they are capable of decomposing into innocuous molecules, which are non-toxic.Poly-3-hydroxybutyrate (PHB), the best-characterized member of microorganism originated Polyhydroxyalkanoates (PHAs), is one of the most attractive biodegradable polymer for several applications due to its biocompatibility and similar properties with polypropylene.Gram-negative microorganisms Alcaligenes eutophus and Alcaligenes lotus are commonly used microorganisms for industrial PHB production. However, since the outer membrane lipolpolysaccharides of those microorganisms include endotoxins, gram-positive bacteria are more convenient for production of PHB to be used in medical applications. Hence, Bacillus species were brought in the center of attraction for PHB production.Since the genes related to PHB production are included in the genome of obligate alkaliphilic Bacillus marmarensis, which was isolated from a mushroom compost in our country in Marmara Region, its PHB production capability was investigated in this thesis. According to the results obtained from experiments, the highest PHB synthesis was achieved at 30°C with 1% inoculation at the end of 24 hr incubation. It was revealed that addition of sucrose, glucose, maltose or fructose to medium supplemented with 0,3% meat extract and 0,5% peptone caused to decrease PHB production , while addition of MgSO4 ve KH2PO4 into the same medium enhanced PHBproduction. When the effect of pH were investigated, although organism is an obligate alkaliphilic Bacillus, it reduced the initial pH in order to produce PHB and the highest PHB synthesis was obtained at initial pH 8,8.Regarding the characterization of PHB produced from B. marmarensis , it was executed that its crystallinity was similar to commercial PHB and thus it can be applicapable for several processes. To our knowledge, this is the first attempt to investigate the production of PHB from obligate alkaliphilic B. marmarensis.