No abstract

One of the benefits of probiotic bacteria is to become a source of protein that can be used as a product in the field of biotechnology with high use value. Proteins derived from bacteria are less widely used compared to animals and fungi. The aim of this study is to analyze the composition of the media and the optimal time for the growth of a consortium of Bacillus cereus bacteria. The experimental method used is a consortium of B. cereus bacteria isolates (5 Strains) six treatments in each B. cereus consortium, namely the addition of a different protein source (eggs and skim milk, the same carbohydrate source, namely Sago) and 3 different concentrations in each protein source (8%, 10%, and 12%) so that the treatment obtained was 6 treatments with 3 replications in each treatment. Measurement of bacterial culture growth was carried out every 6 hours for 24 hours using two methods, namely the TPC method and bacterial cell biomass. Optimal growth was found in sago media which was added in different concentrations, namely 12% due to growth in this medium which was close to the same results as growth in positive control. Growth on biomass measurements showed similar results to the growth pattern similar to TPC. While in milk sago media, the growth is less because the exponential and stationary phases are shorter.

Protein is the main source of nutrition in fish feed. It is necessary to use bacterial single-cell protein (SCPs) as a substitute for conventional protein. This study aims to determine the effectiveness of tofu liquid waste as a growth medium for biomass production of Bacillus cereus as an SCPs. The isolates used were B. cereus SN7 and B. cereus consortium (combination of 5 isolates of B. cereus with different strains). The method used was experimental where isolates were cultured in a medium containing tofu liquid waste with different concentrations (8%, 10%, and 12%) enriched with 10% skim milk. Furthermore, the analysis of an effective growth medium was carried out by three methods, namely total plate count, optical density, and cell-dry weight. Cell biomass measurements were carried out for 24 hours with an observation time of every 6 hours. The results showed the best growth medium used in the culture of B. cereus SN7 and B. cereus consortium was tofu liquid waste at a concentration of 12% enriched with 10% skim milk. In conclusion, the cell mass of B. cereus SN7 and B. cereus consortium significantly increased at 6 to 12 hours.

Dumai is one of the coastal waters of Indonesia that has the potential for the biodiversity of microorganisms including anoxygenic photosynthetic bacteria (APB). Anoxygenic photosynthetic bacteria are bacteria that carry out decomposition activities even though oxygen levels in water and sediment are very little or even absent. This study aims to determine anoxygenic photosynthetic bacteria from aquatic and sedimentary ecosystems in the coastal waters of Dumai, Indonesia. This research was conducted by an experimental method using modified mineral media. The APB was isolated from six different places in sequence, namely Dumai sea station, river prayer room, harbor, shrimp pond area, fish auction place, and, Purnama tour. All bacteria obtained were then characterized by their morphological and physiological characteristics. The isolation results showed that 15 different bacterial isolates were obtained after being determined based on Bergey’s Manual of Determinative Bacteriology. All isolates contained different pigments such as carotenoids, xanthophylls, and, chlorophylls. Thus, further utilization of APB bacteria can be carried out in various microbiological applications such as bioremediation, aquaculture, biofuel, food, and medicines.

Peatlands are terrestrial wetland ecosystems formed from piles of organic matter that decompose into organic deposits. Peat soil has a high potential to produce cellulose which, can be reused by cellulolytic bacteria. This study aims to find out the potential strain of cellulolytic bacteria isolated from peatland ecosystems. The method used was experimental, sequentially, the stages are isolation and screening for cellulolytic bacteria, quantitative testing of cellulolytic activity, characterizing the morphology and physiology of bacteria, and the identification of bacteria based on Bergey’s Manual of Determinative Bacteriology. The screening results obtained seven isolates of cellulolytic bacteria capable of hydrolysed cellulose on 1% Carboxy Methyl Cellulose (CMC) Agar Medium, namely SPS1, SPS2, SPS 3, SDG1, SDG 2, SPW1, and SPW4. Three of seven isolates obtained the highest cellulolytic index sequentially, namely SPS2 of 2.82, SPS3 of 2.65, and SDG1 of 2.47. The cellulolytic activity was indicated by the value of a halo zone around the colonies on 1 % CMC medium after being dripped with Congo red. The halo zone is an early indication to determine the ability of bacteria to decompose cellulose. Based on Bergey’s Manual of Determinative Bacteriology showed that the three isolates had the same characteristics as the genus Bacillus, Lactobacillus and Corynebacterium.