Cellulolytic bacteria are a group of bacteria that have an ability to degrade material containing cellulose and have potency to inhibit the growth of pathogenic bacteria. The bacteria can be found in soil or sediment in the mangrove ecosystem. This research aimed to: 1) isolate cellulolylitic bacteria from mangrove sediments in Dumai Marine Station, of Riau, Indonesia, 2) to examine the antagonism against pathogenic bacteria (Escherichia coli, Pesudomonas aeruginosa, Vibrio alginolyticus), and 3) to identify and the phenotype and genetic characters of the potential isolates. The bacteria were isolated on Zobell Marine Agar 2216 added with carboxymethyl cellulose (CMC). Cellulolytic index value was obtained by reducing clear zone diameter with the bacterial colony diameter. Disc diffusion agar method was used to examine antagonism of selected isolates against pathogens. The isolates were observed for the colony and cell morphology, biochemical and genetically characters. Twenty four isolates showed cellulolytic activity and index values ranged from 1.00 to 2.86 and 0.01 to 2.12, respectively. Nine of selected isolates performed ranges of zone inhibition against E. coli, P. aeruginosa and V. alginolyticus from 2.38 ± 0.21 mm to 3.58 ± 0.83 mm, 2.75 ± 0. 59 mm - 4.81 ± 0.57 mm and 2.28 ± 0.45 mm - 4.68 ± 1.40 mm, respectively. Based on the 16S rDNA sequence analysis, three cellulolytic isolates indicated similarity to Bacillus toyonensis (99.53 %).

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Accumulation of organic component in mangrove ecosystem results in diversity of microorganisms producing extracellular enzymes. Two species of proteolytic bacteria had been isolated and identified from sediment of mangrove ecosystem in the Dumai Marine Station of Riau Province, Indonesia. This research aimed to assess the activity and enzyme production of the proteolytic bacteria, i.e. Bacillus manliponensis (isolate code P.Az6) and B. toyonensis (P.Az20). The growth of bacteria in tryptic soy broth (TSB + skimmed milk) was observed by using spectrophotometer at λ 610 nm and by analysis the total plate counts on Zobell Marine Agar at 0, 6, 12, 18 and 24 hours. Production of enzyme protease was measured from the absorbance values of bacterial supernatant, then were conversed to the protease concentration by using the Bovine serum Albumin Standard. The highest bacterial growth and optimal enzyme production was observed at 6 hours incubation, and period after that showed decrease in growth enzymatic activity. Bacillus toyonensis showed higher bacterial growth and enzyme production than B. manliponensis.

Bacillus toyonensis has been isolated in Dumai mangrove ecosystem of Riau Province. One of factors affecting the growth of the bacteria is growth substrate. Tofu wastewater is rich in nutrition which can be used as substrate for bacterial growth. This research aimed to observe the growth of B. toyonensis in different concentration of tofu wastewater. The bacteria was grown in tofu wastewater at concentrations 8%, 10% and 12% was supplemented with 0.1 g K2HPO4, 0.15 g KH2PO4, 0.15 g NaCl and 0.5 g vitamin B12 in 100 mL distilled water. The bacterial growth was observed by using spectrophotometer at λ 610 nm and by analysis the total plate counts on plate count agar (PCA) at 0, 24, 48, 72 and 96 hour cultivation. Spectrophotometric observation showed that the highest bacterial growth of all tofu wastewater treatments indicated by the addition of 12% tofu wastewater, although the absorbance value was lower than culture in tryptic soy broth (TSB) as control. Exponential growth occurred between 0-24 hour incubation, and the highest growth indicated in substrate contained 12% tofu wastewater. Similarly, total plate count (TPC) analysis indicated that the highest bacterial growth of all treatment occurred at 24 hours incubation, and the highest count was also indicated by treatment of 12% tofu wastewater (2.42±0.06×108 CFU/mL). In conclusion, tofu wastewater can be an alternative substrate for the bacterial growth.

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