STUDI KINETIKA BIODEGRADASI SENYAWA HERBISIDA S-TRIAZINE OLEH BAKTERI KARANG

Abstract

Pusat Studi Pesisir dan Laut Tropis, Lembaga Penelitian Universitas Diponegoro, Tahun 2005, 45 halaman, Ditjend Dikti, Depdiknas, No. Kontrak 031/SPPP/PP/DP3M/IV/2005 tanggal 11 April 2005 Indonesian coral reefs is an ecosystem shallow waters with the most beauty in diversity of the world. The increasing of pesticide used in agriculture have introduced new organic pollutants which are recalcitrant to biodegradation, and their entry into the sea, might be, poses many challenges to the existing coral reefs and even to live in this vicinity in general. Ametryne herbicide is one of the chemical compound of pesticide that is wide spread distributed in Indonesia. It can cause coral reef degradation in particular caused by ocean pollution from agriculture wastes run-off. This problem need to be handled alternatively by exploring bacteria on the surface of coral biofilm that capable to degrade ametryne herbicide compound. Ametryne is used as herbicides to control the turf on rice of gogo and corn of agriculture area. The purposes of this research were to isolate and select coral bacteria that have ability to degrade s-triazine herbicide compound, to study the growth kinetics and subtrate depletion and the bacterial diversity of s-triazine-degrading coral bacteria. The long-term target on this research is to provide an alternative model for coral conservation through the application of indigeneous bacteria on bioremediation of pesticide pollutants. The research was conducted by using exploratif method. Sampling was carried out at Pulau Panjang, lepara waters on four different coral life forms, namely massive, sub-massive, foliose and branching by scuba diving in geographic sample locations. Marine microbiology research was done by preparing Zobell's 2216E media and were used to isolate bacteria from coral tissues. The strain, then, were examined for their ability to degrade s-triazine by using EMBA indicator medium. Selected bacteria were tested on their sensitivity and s-triazine degrading ability. Kinetic study on bacterial growth and substrate depletion was conducted. Phenotypic characteristics on morphological biochemistry were examined to support the result of molecular identification. The molecular phylogenetic approach based on variation in RFLP of 16S rDNA sequences amplified by polymerase chain reaction (PCR) was conducted for identifying triazine-degrading coral bacteria and for estimating genetic relationship among strains. A phylogenetic-tree was constructed from the distance matrix by using CLUSTAL W. neighbour-joining method and PI-IYLIP program. The results showed that among 233 isolates obtained, 83 isolates were capable of degrading ametryne. MT1.8 isolate was selected based on the highest degrading ability (74,86%) and the lowest sensitivity characteristic (8 mm). Growth kinetics studies revealed that the highest spesific growth rate (0,7010 h-1) and the highest spesific substrat removal rate (0,0022 h-1) were achieved at 150 ppm. Growth kinetics of isolate MT1.8 particularly has rate (usiss) was 0,349 with generation time was 1,98 h and saturated concentration (Ks) was 9,56 ppm. Terumbu karang Indonesia merupakan salah satu sumber daya hayati laut dangkal yang memiliki daya pesona karena kekayaan dan keanekaragaman yang paling lengkap di dunia. Namun meningkatnya penggunaan pestisida di bidang pertanian mengakibatkan terganggunya dan menurunnya kualitas lingkungan yang sangat merugikan bagi keseimbangan ekosistem terumbu karang. Herbisida s-triazine adalah salah satu pestisida yang beredar di Indonesia yang keberadaannya dapat menyebabkan kerusakan terumbu karang melalui run-off residu limbah pertanian. Permasalahan ini perlu dilakukan alternatif penanganan dengan mengeksplorasi bakteri pada lapisan karang yang memiliki kemampuan mendegradasi senyawa s-triazine. S-triazine adalah herbisida yang biasa dipergunakan untuk mengendalikan pertumbuhan daun rumput-rumput liar/gulma, perdu di wilayah pertanian padi gogo dan jagung. Target khusus yang ingin dicapai dari penelitian ini adalah mendapatkan strain bakteri yang berasoslasi dengan karang yang memiliki kemampuan mendegradasi senyawa herbisida triazin dan mengetahui kinetika pertumbuhan dan degradasi bakteri karang pendegradasi senyawa triazine serta mengetahui distribusi dan keanekaragaman melalui pendekatan filogenetik molekuler. Adapun tujuan jangka panjang dari penelitian int adalah memberikan model alternatif di dalam pelestarian karang darl pencemaran pestisida melalui bioremedlasi dengan aplikasi bakteri indigeneous strain. Metode yang dilakukan adalah metode eksploratif. Pengambilan sampel dilakukan di Perairan Teluk Awur, Jepara terhadap empat life-form karang (massive, sub-massive, foliose dan branching). Tahap-tahap penelitian yang akan dilaksanakan dalam mencapai tujuan tersebut meliputi survei di lapangan dengan penyelaman scuba untuk mengetahul kondisi ekologis dan kondisi karang. Studi degradasi senyawa pestisida oleh bakteri yang berasosiasi dengan karang dilakukan dengan isolasi bakteri dad jaringan karang, purifikasi, uji degradasi, uji sensitivitas, dan kinetika pertumbuhan dan penggunaan senyawa pestisida. Studi filogenetik molekuler meliputi ekstraksi DNA, amplifikasi DNA, gen sequencing 165 rRNA, dan anallsis homologi dengan menggunakan program BLAST dan RDP database. Konstruksi pohon filogenetik dilakukan dengan metode neighbour-joining CLUSTAL W dan program PHYLIP. Hasil penelitian menunjukkan dart 233 isolat yang diperoleh, 83 diantaranya menunjukkan kemampuan mendegradasi senyawa s-triazine. Isolat MT1.8 diseleksi berdasarkan daya degradasi tertinggi (74,85%) dan derajat sensitivitas rendah (8 mm). Uji kinetika isolat MT1.8 mempunyai laju pertumbuhan spesifik tertinggi (0,7010 jam-I) dan laju penggunaan substrat tertinggi (0,0022 jam-1) yang dicapai pada konsentrasi 150 ppm. Isolat MT1.8 didapatkan laju pertumbuhan maksimum (u„,aks) sebesar 0,349 jam-I dengan waktu generasi (tg) 1,98 jam dan nilai tetapan kejenuhan (K,) sebesar 9,56 ppm.