Extraction of Chitin From Shrimp Shell by Successive Two-Step Fermentation of Exiguobacterium profundum and Lactobacillus acidophilus

As an environmentally friendly and efficient method, successive two-step fermentation has been applied for extracting chitin from shrimp shells. To screen out the microorganisms for fermentation, a protease-producing strain, Exiguobacterium profundum, and a lactic acid-producing strain, Lactobacillus acidophilus, were isolated from the traditional fermented shrimp paste. Chitin was extracted by successive two-step fermentation with these two strains, and 85.9 ± 1.2% of protein and 95 ± 3% of minerals were removed. The recovery and yield of chitin were 47.82 and 16.32%, respectively. Fourier transform infrared spectroscopy, X-ray diffraction, and scanning electron microscopy (SEM) were used to characterize the chitin. The crystallinity index was 54.37%, and the degree of deacetylation was 3.67%, which was lower than that of chitin extracted by the chemical method. These results indicated that successive two-step fermentation using these two bacterial strains could be applied to extract chitin. This work provides a suitable strategy for developing an effective method to extract chitin by microbial fermentation.

Green synthesis of silver nanoparticles by Exiguobacterium profundum isolated from carpet industry effluent

Green synthesis of silver nanoparticles using microorganisms has received profound interest because of their potential to synthesize nanoparticles of various size, shape and morphology. The main objective of the current study was to evaluate the synthesis of silver nanoparticles by a bacterial strain, Exiguobacterium profundum with potential dye degrading ability isolated from carpet industry effluent. The strain was tested for its ability to degrade various dyes including Methylene Blue, Malachite Green, Congo Red, Crystal Violet, Coomassie Brilliant Blue, Methyl Red, Sudan Black. Treatment of the bacteria with 1 mM AgNO3, showed its ability to form silver nanoparticles. This was confirmed by visual observation and UV–Vis absorption at 450 nm. Further characterization of nanoparticles by Scanning electron microscopy confirmed the size of silver nanoparticles in 20-40 nm range. Therefore, the present study is a demonstration of an efficient synthesis of stable silver nanoparticles using Exiguobacterium profundum which could be utilized in dye degradation thereby reducing the pollution from industrial effluents.

Molecular identification of pathogenic bacteria causing foodborne disease in Caulerpa racemosa

Caulerpa racemosa is a green algae consumed by people in northern coastal areas. C. racemosa has a habitat attached to the shallow seabed. C. racemosa usualy consumed fresh without any cooking process so that the contamination of microorganisms can be eaten. Molecular identification using 16S rRNA is needed to determine the type of bacterial contaminants in C. racemosa. The isolates of C. racemosa were cultured in HIA, BAP, and BHI media. Bacteria from BHI media were isolated by DNA, PCR for 16S rRNA gene, and sequencing. Bacteria isolate C. racemosa was found to have the α-hemolytic ability in BAP media. The sequencing analysis showed that the three bacterial colonies of C. racemosa isolate had high similarity with V. parahemolyticus, Caldalkalibacillus mannanilyticus, and Exiguobacterium profundum.

Screening of anti-Candida albicans metabolites produced by marine sponge-associated bacteria

This study selected bacteria with high anti-Candida albicans (CA) activity among ten bacteria isolated from marine sponges. Bacteria were cultivated using the basal medium to produce the extract. Minimum Inhibitory Concentration (MIC) microdilution broth was used as an anti-CA assay followed by TLC-direct bioautography to characterize their active compound with spray reagents. The bacteria determination was done by molecular approaches using Repetitive-Element Sequences-based-PCR (rep-PCR) and amplification of 16S rDNA partial gene sequences, continued with BLAST analysis. The four out of ten tested bacteria had high anti-CA compounds and were potentially to be produced on a larger scale using the basal medium, which was BYT5C4, BYT5C5, BYT1A, and BYT7, with MIC of 1 mg/mL against 7.5×106 CFU/mL CA. TLC-bioautography test results showed that all metabolites from each isolate had different Rf and types of metabolites. Rep-PCR test showed that four bacteria had a low similarity index, indicating that they were different species. Based on molecular identification results, the BYT5C4, BYT5C5, BYT1A, and BYT7 isolates are strictly related to Brevibacterium casei, Exiguobacterium profundum, Micrococcus lylae, and Bacillus firmus, respectively. The active metabolites identified in this study can be isolated to determine the active molecules and their inhibitory routes to fungal growth. It is worth noting that additional research might be conducted to compare the activity of each antifungal metabolite to the synergistic activity of numerous antifungal metabolites detected in plant extracts.

STUDIES ON BIOSURFACTANT PRODUCED USING Exiguobacterium profundum

Background: The manufacture of pharmaceutical preparations generally adds surfactants. Microbial biosurfactants can be an alternative because biodegradable and have antibacterial properties. Objective: This study aimed to examine the biosurfactant activity of Exiguobacterium profundum.Methods: Hemolysis and spreading oil tests were performed as an initial screening. Biosurfactant production was carried out by growing bacteria on oil-enriched media with shaker system for 7 days. Biosurfactant activity can be seen from the emulsification index, while the characterization of biosurfactant were used thin layer chromatography and antibacterial qualitative testing.Results: Exiguobacterium profundum could spread the oil layer and form micelles. The emulsification index on days 0, 1, 3, 5, and 7 showed percentage in sequence 44.83%, 48.28%, 48.28%, 40%, and 43.75%. The result of TLC showed lipopeptide group which is marked with red stain with ninhydrin appearance. Antibacterial testing using Escherichia coli showed the formation of clear zones around the disk paper.Conclusion: The biosurfactant produced by Exigoubacterium profundum can be classified into lipopeptide group which has antibacterial activity against gram-negative.

IDENTIFICATION AND CHARACTERIZATION OF PIGMENTED BACTERIA ISOLATED FROM MALAYSIAN SEAWATER

Purpose of study: Bacteria can naturally produce pigments that can be useful for various applications as they possess antimicrobial metabolites among other numerous benefits towards the human health. This study was carried out to identify the species of marine bacterial isolates PMA, PM3C1 and PM5C1 exhibiting yellow, orange and green colors respectively. Methodology: The current study is using Polymerase Chain Reaction (PCR) amplification and sequence analysis of their 16S rRNA gene. The stability of pigments extracted from the bacterial samples was also analyzed against different temperature and light conditions. Main Findings: Sequence alignment using BLAST revealed that the yellow, orange, and green-pigmented bacteria have 84% similarity with Staphylococcus aureus, 85% similarity with Exiguobacterium profundum and 95% similarity with Pseudomonas aeruginosa respectively. The green pigment showed major changes in color following exposure to sunlight and fluorescent light, and when incubated at 24°C and 50°C. Exposure to direct sunlight also results in the reduction of color for the yellow and orange extracts, while no effect was observed for both pigments under fluorescent light. Incubation at 50°C results in the reduction of the orange color, while the yellow pigment was observed to be unaffected suggesting its stability at high temperature. Implications: Natural pigments production can provide many advantages including reduction of pollution generation, ease of disposal and other benefits to the human health.