DISTRIBUSI DAN KEMELIMPAHAN BAKTERI AEROBIK ANOKSIGENIK FOTOTROFIK PANTAI SIUNG, GUNUNGKIDUL, YOGYAKARTA

Victor Aprilyanto, Prof. Drs. Langkah Sembiring, M.Sc., Ph.D.

2013 | Tesis | S2 Biologi

Distribusi dan kemelimpahan bakteri aerobic anoxygenic phototrophic (AAP) pada laut tropika, khususnya pantai selatan Jawa belum banyak diteliti. Penelitian ini bertujuan untuk mengungkap distribusi dan kemelimpahan bakteri AAP pada perairan pesisir pantai Siung, Gunungkidul, Yogyakarta. Pengambilan sampel dilakukan pada kolom air daerah tangkapan ikan nelayan setempat pada 0, 4, 6, dan 20 meter yang masing-masing mewakili jeluk permukaan, jeluk subsurface, jeluk transparansi cahaya, dan jeluk afotik. Total bakteri dan komunitas bakteri AAP masing-masing dihitung dengan mikroskopi epifluoresens dan real-time quantitative PCR (qPCR) gen pufM. Strain bakteri AAP diisolasi secara selektif dengan menumbuhkan sampel air pada medium PPES–II dan kemudian setiap koloni berwarna di-skrining untuk pigmen bacteriochlorophyll-a intraselular. Parameter fisikokimia perairan yang diukur meliputi suhu, pH, salinitas, oksigen terlarut, dan nutrien (NO3 –, NH4 +, PO4 3–, SO4 2–). Hasil menunjukan bahwa komunitas bakteri AAP terdistribusi secara tidak merata dengan kemelimpahan berkisar antara 1 hingga ~2,5% dari total bakterioplankton di kolom air. Persentase bakteri AAP terhadap total bakteri terendah dan tertinggi secara berturut-turut berada pada permukaan dan zona kompensasi cahaya. Di sisi lain, hanya satu strain bakteri AAP yang berhasil terisolasi yang kemudian teridentifikasi sebagai anggota genus Roseobacter. Dengan demikian, dapat disimpulkan bahwa komunitas bakteri AAP terdistribusi di sepanjang kolom air dengan kemelimpahan rendah pada perairan pesisir Gunungkidul, Yogyakarta.

This research aimed to reveal the distribution and abundance of aerobic anoxygenic phototrophic (AAP) bacteria in the tropical coastal waters of Gunungkidul, Yogyakarta, which has not been much investigated. Sampling location was determined at the local fish catchment area. Samples in five replicates were collected vertically at four depths (0, 4, 6, and 20 m); representing the surface, subsurface, compensation, and aphotic depth, respectively. Total and AAP bacteria were each enumerated using epifluorescence microscopy and realtime quantitative PCR (qPCR) of environmental pufM gene, respectively. Strains of AAP bacteria were selectively isolated by growing the water sample on PPES– II medium and then each growing colored colonies were screened for the intracellular bacteriochlorophyll-a. Water physicochemical parameters consisting temperature, pH, salinity, dissolved oxygen, and nutrients (NO3 –, NH4 +, PO4 3–, SO4 2–) were also measured. The results showed that AAP bacteria were distributed non-uniformly distributed with abundances ranging up from 1 to ~2.5% of total bacterioplankton throughout the water column. The lowest and highest percentage of AAP bacteria to total bacterioplankton were at the surface and compensation depths, respectively. Meanwhile, only a single strain of AAP bacteria was succesfully isolated which was then identified as a member of Roseobacter genus. Therefore, it can be concluded that the community of AAP bacteria was distributed throughout the water column with low abundances in the coastal waters of Gunungkidul, Yogyakarta.

Kata Kunci : bakteri AAP, pesisir, pufM