Rhizofiltrasi kromium dan keragaman komunitas Rhizobakteri pada tanaman air

SAFARRIDA, Anna, Dr.Ir. Ngadiman, M.Si

2007 | Tesis | S2 Bioteknologi

Logam berat dalam limbah industri merupakan bahan pencemar lingkungan yang mendapatkan perhatian global. Salah satu upaya untuk mengatasi masalah tersebut adalah memanfaatkan tanaman untuk menyerap logam dalam medium cair atau dikenal sebagai rhizofiltrasi. Disisi lain, keberadaan logam berat dalam media tanaman tersebut juga mempengaruhi komunitas rhizobakteri. Penelitian ini bertujuan untuk mengetahui ketahanan dan serapan tanaman air terhadap kromium, keragaman komunitas rhizobakteri tanaman air yang dipapar kromium, dan isolasiidentifikasi rhizobakteri yang tahan kromium. Empat tanaman air (Pistia stratiotes, Eichornia crassipes, Lemna minor, dan Salvinia sp.) ditumbuhkan pada medium buatan (Hoagland) yang dipasok 0, 1, 2, 4, dan 8 ppm Cr. Berdasarkan daya tahan dan serapan kromium, tanaman terseleksi diujikan lebih lanjut dalam limbah cair industri penyamakan kulit. Kemampuan toleransi dan serapan tanaman terhadap kromium didasarkan pada pengamatan morfologi dan analisis kadar Cr dalam biomas. Keragaman komunitas rhizobakteri dianalisis melalui pendekatan culture independent dan culture dependent. Kolonikoloni yang berbeda pada culture dependent diseleksi ketahanannya terhadap kromium dan dianalisis keragamannya dengan Rep-PCR. Isolat yang terpilih diidentifikasi berdasarkan sekuen parsial gen 16S rDNA. Dalam medium Hoagland dan limbah cair industri penyamakan kulit, P. Stratiotes dan Salvinia sp. berturut-turut mempunyai ketahanan dan serapan paling rendah dan paling tinggi terhadap Cr dibandingkan dengan tanaman lain yang diujikan. Pada pendekatan culture independent dan culture dependent, paparan kromium menurunkan keragaman komunitas rhizobakteri baik pada P. stratiotes maupun Salvinia sp. dimana keragaman komunitas rhizobakteri pada P. stratiotes lebih rendah dari pada Salvinia sp. Hasil pengujian ketahanan terhadap Cr diperoleh 6 isolat rhizobakteri yang tahan sampai 40 ppm. Berdasarkan sekuen parsial gen 16S rDNA, isolat P01, P41, P603, S01, S81, dan S401 berturut-turut teridentifikasi sebagai Aeromonas sp., Rhodococcus fascians, Bacillus sp., Pseudomonas mosselii, Agrobacterium tumefaciens, dan Brevibacterium sp..

Existance of heavy metals in industrial waste is gaining global attention since their negative impact to environment. An effort to solve the problem is to use plant to absorb metal in liquid medium, known as rhizofiltration. In the other side, the metal exposure in plant medium can influence rhizobacterial communities associated with aquatic plants. This research is aimed to select aquatic plants which show relatively resistant or susceptible to chromium, diversity of rhizobacterial community after chromium exposure, isolation and identification of Cr resistant rhizobacteria. Four aquatic plants (Pistia stratiotes, Eichornia crassipes, Lemna minor and Salvinia sp.) were grown in artificial medium (Hoagland) which was supplemented by 0, 1, 2, 4 and 8 ppm chromium. Based on resistance and absorption of chromium, selected plants are tested further in liquid waste of tanning industry. The plants resistance and absorption toward chromium was absorved based on morphology and chromium content of chromium in biomass. Diversity of rhizobacterial community was analyzed through by culture independent and culture dependent approaches. Different colonies of culture dependent was subsequently cultivated on media with measured chromium content. Selected isolates were they distinguished by Rep-PCR and identified using partial sequence of 16S rDNA gene. In Hoagland and liquid waste of tanning industry, P. stratiotes and Salvinia sp. showed highest and lowest chromium resistance and absorption compared to other plants examined respectively. Both culture independent and dependent, chromium exposure decreased rhizobacterial communities diversity of P. stratiotes and Salvinia sp. Where diversity of rhizobacterial communities in P. stratiotes was lower than in Salvinia sp. Six rhizobacterial isolates were known resistant to 40 ppm Cr. Based on partial sequence of 16S rDNA gene, isolate P01, P41, P603, S01, S81 and S401 was identified as Aeromonas sp., Rhodococcocus fascians, Bacillus sp., Pseudomonas mosselii, Agrobacterium tumefaciens and Brevibacterium sp. respectively.

Kata Kunci : Rhizofiltrasi,Rhizobakteri Tanaman Air, rhizofiltration, chromium, communities, rhizobacterial