Keanekaragaman Bakteri Serasah Daun Rhizophora Apiculata yang Mengalami Dekomposisi pada Berbagai Tingkat Salinitas di Kota Pari Pantai Cermin Sumatera Utara

Abstract

ABSTRACT The aims of this study were investigated the effect of salinity level on the diversity of bacteria and remaining in the C, N and P during the process of composition of the R. apiculata leaf litter. The research has been conducted at the mangrove forest of Kota Pari Cermin Beach North Sumatera. The leaf litter were collected using litter traps made of nylon mesh 2 mm pore. The leaf was collected for two weeks period. Litter bag was filled with 50 g leaf litter and put on the forest’s floor in four different salinity level, the litter bag was observed each 15 days of decomposition. The results of our investigation indicated that tottaly 18 species of bacteria were isolated from R. apiculata leaf litter undergoing the decomposition, including Bacillus (5 species), Flavobacterium (1 species), Alcaligenes (1 species), Sporosarcina (2 species), Staphylococcus (1 species), Micrococcus (2 species), Kurthia (1 species), Escherichia coli (1 species), Pseudomonas (1 species), Planococcus (2 species), Mycobacterium (1 species). The highest amounts of bacteria at 10-20 ppt were 82,69 X 107 CFU/ml, whereas the lowest of bacteria at >30 ppt were 57,03 X 107 CFU/ml. Bacillus sp. 1 was dominant species during decomposition period. The species diversity indices in the leaf litter decomposition at 0-10 ppt were 2,41, at 10-20 ppt were 2,58, at 20- 30 ppt were 2,20, at >30 ppt were 2,06. The frequency of the bacteria species colonization during the decomposition process ranged from 12,5 to 100%. The salinity level were influenced rate of decomposition R. apiculata in the leaf litter. The Salinity level on rate of decomposition leaf litter R. apiculata at 0-10 ppt were 0,60, at 10-20 ppt 0,50 ppt, at 20-30 ppt were 0,44, at >30 ppt were 0,45. The salinity level were influenced to C, N and P remaining in the leaf litter a long decomposition period. Sampel were analyzed for change in total C, N and P during decomposition period. The highest content of C was found in the leaf litter decomposed at 0-10 ppt, while the lowest content of C was found in the leaf litter decomposed at >30 ppt. The highest content of N was found in the leaf litter decomposed at >30 ppt, whereas the lowest content of N was found in the leaf litter decomposed at 10-20 ppt. The highest content of P was found in the leaf litter decomposed at >30 ppt, whereas the lowest content of P was found in the leaf litter at 0-10 ppt. Keywords: Rhizophora apiculata, Bacteria, Decomposition, Diversity, Leaf Litter, Mangrove, Salinity

ABSTRAK Penelitian ini bertujuan untuk mengetahui pengaruh tingkat salinitas terhadap keanekaragaman bakteri, laju dekomposisi serasah dan kandungan unsur hara C, N dan P pada serasah daun R. apiculata yang mengalami proses dekomposisi. Penelitian dilakukan di kawasan hutan mangrove Kota Pari Pantai Cermin Sumatera Utara. Serasah dikumpulkan menggunakan kantong serasah yang terbuat dari jaring nilon dengan mesh 2 mm. Serasah daun dikumpulkan selama 2 minggu. Kantong serasah diisi 50 gram daun kering dan diletakkan di lantai hutan mangrove pada 4 lokasi yang memiliki tingkat salinitas yang berbeda, pengamatan dilakukan tiap 15 hari. Hasil penelitian menunjukkan bahwa ada 18 jenis bakteri yang berhasil diisolasi dari serasah daun R. apiculata yang mengalami proses dekomposisi yaitu Bacillus (5 jenis), Flavobacterium (1 jenis), Alcaligenes (1 jenis), Sporosarcina (2 jenis), Staphylococcus (1 jenis), Micrococcus (2 jenis), Kurthia (1 jenis), Escherichia coli (1 jenis), Pseudomonas (1 jenis), Planococcus (2 jenis), Mycobacterium (1 jenis). Jumlah bakteri yang paling banyak ditemukan pada tingkat salinitas 10-20 ppt yaitu 82,69 X 107 CFU/ml, sementara jumlah bakteri paling sedikit ditemukan pada tingkat salinitas >30 ppt yaitu 57,03 X 107 CFU/ml. Bakteri yang paling sering ditemukan selama proses dekomposisi adalah Bacillus sp. 1. Indeks keanekaragaman jenis bakteri pada serasah daun R. apiculata yang mengalami proses dekomposisi pada tingkat salinitas 0-10 ppt adalah 2,41, 10-20 ppt adalah 2,58, 20-30 ppt adalah 2,20, >30 ppt adalah 2,06. Frekuensi kolonisasi spesies bakteri antara 12,5 % sampai 100%. Tingkat salinitas berpengaruh terhadap laju dekomposisi pada serasah daun R. apiculata mulai dari 15 sampai 120 hari. Laju dekomposisi pada tingkat salinitas 0-10 ppt adalah, 0,60, 10-20 ppt adalah 0,50, 20-30 ppt adalah 0,44, >30 ppt adalah 0,45. Tingkat salinitas berpengaruh terhadap kandungan unsur hara C, N dan P pada serasah daun yang mengalami proses dekomposisi. Kandungan unsur hara C tertinggi terdapat pada serasah daun yang mengalami proses dekomposisi pada tingkat salinitas 0-10 ppt, sedangkan kandungan unsur hara C terendah terdapat pada tingkat salinitas >30 ppt. Kandungan unsur hara N tertinggi pada serasah daun R. apiculata yang mengalami proses dekomposisi terdapat pada tingkat salinitas >30 ppt, sedangkan kandungan unsur hara N terendah terdapat pada tingkat salinitas 10-20 ppt. Kandungan unsur hara P tertinggi terdapat pada tingkat salinitas >30 ppt sedangkan kandungan unsur hara P terendah terdapat pada tingkat salinitas 0-10 ppt. Kata kunci: Rhizophora apiculata, bakteri, dekomposisi, keanekaragaman, mangrove, Salinitas