Metallothionein induction in two species of pseudomonas exposed to cadmium and copper contamination

The main objective of this study was to investigate the effect of cadmium [2] and copper [2] salts concentrations on uptake, tolerance, growth pattern and metallothionein induction as a biomarker by two bacterial strains including Pseudomonas aeruginosa and Pseudomonas putida PTCC 1694. For this purpose, the minimum inhibition concentration, minimum bactericidal concentration, growth and uptake patterns of Pseudomonas aeruginosa and Pseudomonas putida were determined in culture media with 0.09-10mM/L of Cd and Cu salts in pH7 +/- 0.2= at 30 +/- 2 Degree C. Growth rate and amount of metal uptake were determined by spectrophotometer and atomic absorption assay every 24 hours for 14 to 23 days. Biosorption of the heavy metals on the bacterial cell wall surfaces after preparation were analyzed by Scanning Electron Microscopy [SEM] equipped with Energy Dispersive Spectroscopy [EDS]. Metallothionein production was evaluated by silver saturation methods. The results showed that the growth was directly inhibited at the concentration of 1.5 mM/L Cd[2] and 9 mM/L Cu[2] for P. aeruginosa and 0.95 mM/L Cd[2] and 7.5 mM/L Cu[2] for P. putida. Results of the growth pattern showed that the log phase for Pseudomonas aeruginosa and Pseudomonas putida lasted 48 and 121 hours, 217 and 121 in presence of cadmium and copper, respectively. The stationary phase was very short and very soon after log phase, the microorganisms went into death phase. The maximum biosorption of metal from cultures of two strains was 36.6% and 28% of cadmium and 80% and 47% of copper of final concentration. The result of elemental analysis with SEM-EDS approved surface adsorption of cadmium and copper. Since the exact number of Ag-binding sites per metallothionein molecules is unknown for Pseudomonas putida, results were expressed as nanomoles of Agbinding site per gram of wet weight as equal to 0.0033 and 0.0031

[Potential ability of probiotics isolated from Iranian local yogurts to produce lactacins]

Lactic acid bacteria are microorganisms with ability to produce a wide range of chemical compounds that affect the shelf-life of foods. The objective of this study was to determine the potential ability of probiotics isolated from Iranian local yogurts to produce lactacins and assess their antimicrobial activity. Samples were prepared from 20 kinds of local yogurts [Arak, Sarein, Shahandasht, and Damavand] to isolate and purify lactic acid bacteria in an MRS agar medium and compare them with 3 isolated probiotics strains, i.e., L. casei [PTCC 1608], L. reuteri [PTCC 1655] and L. rhamnosus [PTCC 1637]. The inhibition of growth zone was tested, by the well diffusion agar method, on 5 gram-positive and gram-negative bacterial strains. The maximum amount of antimicrobial substance produced was determined by comparing the growth curves, and extraction purification of the lactacins was done by dialysis. In each stage the amount of protein extracted was determined by the Lowry method, and the recovery percent, total protein, unit activity, specific activity, purification fold, and bacteriocin field were calculated. The molecular weight of the extracted protein was determined by the SDS-PAGE method. A total of 21 lactic acid bacterial strains were isolated. The maximum antimicrobial components were found to be produced by Ln11 and Ld17 during the logarithmic phase of growth curve. The results of SDS-PAGE showed lactacins with molecular weights ranging from 48 to 57 KD. Considering the antimicrobial properties of the bacterial strains isolated from the local yogurts, they can be used as local probiotic strains in production of fermented foods in preference to the 3 standard strains

effects of garlic and cardamom extracts on morphology and physiology properties methicillin resistant staphylococcus aureus [MRSA] and Pseudomonas aeruginosa

Garlic has been known as an important medicinal plant for centuries and belonging to the Liliaceae family. Cardamom is the dried fruit of the tall perennial herbaceous plant, Elettaria cardamomum Maton, and belonging to the Zingiberaceae. family. The purpose of this study was to investigate the effect of aqueous extract of garlic and methanolic extract of cardamom on MRSA and P. aeruginosa. Dry garlic bulbs [l00g] were peeled and homogenized distilled water [1:1 w/v], using a blender and 50% juice of garlic is obtained, centrifuged and then the supernatant of garlic juice is collected and passed through a 0.45 micro m filter and stored at 4 for further experiments. Also after collecting cardamom seeds, drying and making it powder, extracts were obtained by using percolation method with methanol. for evaluating the antibacterial activity of the extracts or garlic and cardamom, the microbial suspension was prepared by direct colony suspension method and different dilutions of extracts [1:2, 1:4, 1:8,. .., 1:64 v/v for garlic; 800, 650, 400,. .., 50 micro g/ml for cardamom] were prepared and tested against of MRSA ATCC 33591 and P. aeruginosa ATCC 27853. Minimum Inhibition Concentration [MIC] was obtained via Disc diffusion and Broth dilution and well diffusion method. We also analyzed morphological changes of MRSA and P.aeruginosa by light microscopy [LM] and biochemical properties was studied by inoculation of low concentrations of garlic and cardamom extracts to bacterial culture. The results showed that cardamom extract has no effect against Pseudomonas aeruginosa but garlic extract is effective on P. aeruginosa. Garlic extract [1:2, 1:4, 1:8, 1:16, containing 220, 110, 55, 27.50 micro g/ml allicin] inhibited the growth of MRSA and concentrations of 1:2 to 1:8 [v/v] inhibited the growth of Pseudomonas aeruginosa. Further more MRSA is sensitive to cardamom extract in 800 to 200 micro g/ml. In general, the minimal inhibitory concentration for MRSA [garlic MIC 1:16; allicin mean MIC 7.50 micro g/ml] were lower than for P. aeruginosa [garlic MIC 1:8; allicin mean MIC 55 micro g/ml].The treatment group with garlic extract showed a changed form of morphology such as cellular swelling, partially distored shape and changes in the size of bacteria, but cardamom extract dose not reveal any changes compared to the control. It was also observed in low concentrations of garlic, production of catalase enzyme and pyocyanine pigment by P.aeruginosa were decreased but it increased strain hemolysis ability, and acid production from saccharose, manitol by MRSA changed to negative. This research showed that garlic and cardamom extracts have different antibacterial properties against 2 tested bacteria

Removal of lead and chromium from aqueous solution by bacillus circulans biofilm

The different methods are used for the removal of heavy metals as important contaminants in water and waste water. Biosorption is an alternative to traditional physicochemical in removing toxic metals from wastewaters and groundwater resources. In this study biosorption of lead and chromium ions from solution was studied using Bacillus circulans isolated from Anzali wetland in batch and biofilter modes and optimum conditions were determined. The experimental results showed 900-950 mg/L and 1050-1100 mg/L, for minimum bactericidal concentration and minimum inhibitory concenteration for lead and chromium, respectively. Results of metal concentration in solution containing 500 mg/L in batch culture showed a reduction about 65% and 48% in five and four days for lead and chromium, respectively. The highest value of lead and chromium uptake in solution with 500 mg/L was 78% and 40% in biofilter mode, respectively. The biosorption of lead and chromium were increased up to pH=5.5, 6, 5.5 and 7, respectively. In the other hand, maximum sorption occurred at neutral pH. There was a significant decreasing of biosorption levels by lowering pH fewer than 3. Accumulation of lead and chromium was determined by scanning electron microscopy analysis of the biofilm exposed to 500 mg/L metal concentration. Based on this analysis, the highest metal concentrations were observed in regions with including bacteria

Recovery of chitin and chitosan from shrimp waste by chemical and microbial methods

Shrimp waste is the most important chitin source for commercial use. In this study chitin and chitosan were extracted from Penaeus semisulcatus waste collected from a shrimp processing landing center situated at Persian Gulf in south of Iran by chemical and microbial methods. Chitin and chitosan were extracted by alkali-acid treatment and the yields were 510 and 410mg/g, respectively. Demineralization is an important step in the chitin purification process from shrimp waste. Chemical extraction method included the use of NaOH solution and acetic acid. In microbial extraction, organic acids [lactic acid] produced by probiotic bacteria was used to demineralize microbial deproteinized shrimp shells. The study showed that the effectiveness of using lactic acid bacteria especially added Fe [NO[3][3] as extra nitrogen source for demineralization of shrimp shells than chemical method [1750 against 810mg/g]. Chitin and chitosan extracted from shrimp waste by chemical and microbial methods was crystalline powder, non-harmful and odorless, white and off-white, respectively. The moisture content was calculated as 63.8%. The amount of Ca, Fe, Cu and Mn present in the shells was 168, 35.58, 38.28 and 6.72mg/L, obtained by atomic absorption spectroscopy, respectively. The amount of calcium in the shells was 25 times higher than manganese. The results suggested Lactobacillus plantarum [PTTC 1058] is an attractive source of recovery for chitin and chitosan

Biocontrol of Aspergillus flavus and aflatoxin B1 production in corn

The potent mycotoxin aflatoxin B1 is a secondary metabolite of Aspergillus fungi that grow, on a variety of food and feed commodities at any stage during growth, harvest, storage and transportation. The occurrence of aflatoxin contamination is global, with severe problems especially prevalent in developing countries. In present study, corn samples were contaminated with aflatoxin B1 in the concentration of 240 micro g/kg. Four trials were inoculated by Lactobacillus plantarum [PTCC 1058]. Three control assays were analysed in the same conditions. All the assays were kneaded and incubated for 4-7 days at 37[degree sign] C. Aflatoxin B1 was determined after extraction by HPLC. Results showed a drastic removal of the mycotoxin with a reduction of 77% for Aflatoxin B1 by Lactobacillus plantarum. In the Inoculated corns, spore germination of A. flavus was totally inhibited. Results in inoculated spikes showed a high percentage of reduction of aflatoxin after incubation by Lb. plantarum. Gram staining of a sample from inoculated corns and microscopic observation demonstrated that the growth of A. flavus spores was totally inhibited by Lb. plantarum. Fungal spores were surrounded by Lactobacillus plantarum and spores were degraded

Alginate biopolymer production by Azotobacter chroococcum from whey degradation

The potential of three Azotobacter chroococcum strains for whey degradation and alginate production were investigated. After dilution, samples were spread plated on isolation agar and Manitol agar and incubated at 30 °C for 24 h. Microorganisms were screened for their ability to whey degradation and alginate production based on colony morphology, negative and capsule staining, ability to decrease the apparent turbidity of the fermentation broths in batch and semi continuous culture by spectrophotometer assay at 400 nanometer and tensiometer assay. Of the three strains tested for whey degradation, only Azotobacter chroococcum 1723 produced significant apparent growth on whey broth and could decrease about 70% of turbidity in fermentation broth during 6 days in batch culture. Colonies of this strain was characteristically yellow, large, moucoid and slimy on whey agar than Manitol agar after 24 h at 30 °C. Transmission electron microscopy assay and Carbazole reagent were used to recognize the alginate biopolymer. After optimizing environmental factors such as pH, salt concentration and temperature, this strain was able to produce exopolysaccharide greater than 5 mg/mL. Optimum results were obtained when using whey broth as a fermentation medium without extra salt, temperature at 35 °C and pH 7. Increasing inorganic and organic nitrogen sources [yeast extract and NH[4]NO[3]] reduced whey degradation at least 30%. Transmission electron microscopy assay showed a net-structured polysaccharide capsule around the cells. Semi-continuous culture results demonstrated that, alginate production as well as whey degradation was decreased [1 mg/mL and 30%]

Extraction of astaxanthin esters from shrimp waste by chemical and microbial methods

The carotenoid pigments specifically astaxanthin has many significant applications in food, pharmaceutical and cosmetic industries. The goal of this research was the extraction of Astaxanthin from a certain Persian Gulf shrimp species waste [Penaeus semisulcatus], purification and identification of the pigment by chemical and microbial methods. Microbial fermentation was obtained by inoculation of two Lactobacillus species Lb. plantarum and Lb. acidophilus in the medium culture containing shrimp waste powder by the intervention of lactose sugar, yeast extract, the composition of Both and the coolage [-20°C]. The carotenoids were extracted by an organic solvent system. After purification of astaxanthin with the thin layer chromatography method by spectrophotometer, NMR and IR analysis the presence of astaxanthin esters was recognized in this specific species of Persian Gulf shrimp. Results obtained from this study showed that the coolage at -20°C not only does not have an amplifiying effect on the production of astaxanthin but also slightly reduces this effect. Also the effect of intervention of lactose sugar showed more effectiveness in producing astaxanthin than yeast extract or more than with the presence of both. The results also indicated that there is not much difference in the ability of producing the pigment by comparing both Lb. plantarum and Lb. acidophillus. Also results showed the microbial method of extraction of astaxanthin is more effective than chemical method. The pigment extracted from certain amount of shrimp powder, 23.128 mg/g, was calculated

Production and recovery of poly- beta -hydroxybutyrate from whey degradation by azotobacter

Three strains of Azotobacter chroococcum were studied to produce poly- beta hydroxybutyrate as a inclusion body by whey degradation. Optimum degradation whey results were obtained when using whey broth as a fermentation medium without extra salt, temperature at 35°C and pH 7 [P<0.05]. Lambda max for whey broth medium was determined probably about 400 nm. The effect of different nitrogenous rich compounds [NH[4]NO[3], Bactopeptone, Casein, Yeast extract, Meat extract, Protease peptone and Tryptone] on whey degradation showed that incorporation of nitrogenous compounds into the medium did not increase whey degradation by Azotobacter chroococcum 1723 [P<0.05]. But poly- beta hydroxyl-butyrate production was increased in presence Meat extract up to 75% of the cell dry weight after 48h. The addition of nitrogenous sourced [except ammonium nitrate] had a positive effect on poly- beta hydroxyl-butyrate production as it peaked in the presence of Meat extract and 4.43 g/L was accumulated in comparison to 0.5g at diazotrophically growing cells. Increasing the O[2] values resulted by shaking at 122 rpm in decreased poly- beta hydroxyl-butyrate yield form 4.43 to 0.04 g/L. The results show that this medium supports the growth of strain 1735 and also that this waste could be utilized as a carbon and nitrogen source. Production of poly- beta hydroxyl-butyrate by using whey as a medium looks promising, since the use of inexpensive feed-stocks for poly- beta hydroxyl-butyrate is essential if bioplastics are to become competitive products