Effect of Nutrient Solution Composition on Bio-Cemented Sand

Microbial-induced carbonate precipitation is an environmentally friendly foundation treatment technology that effectively improves soil engineering performance. The various nutrient components of liquid curing compounds significantly influence the curing effect. On the basis of penetration, dry density, water absorption, and unconfined compressive strength tests, this study showed the effect of nutrient solution composition, including urea, calcium chloride, sodium bicarbonate, ammonium chloride, and nutrient broth, on the physicomechanical properties of bio-cemented sand. The morphological differences of calcium carbonate precipitates under nutrient solution composition were compared through scanning electron microscopy (SEM). Results showed that the curing effect of compound nutrient solution was improved compared with the basic nutrient solution (urea and calcium chloride). Among the individual components added, ammonium chloride had the most remarkable effect, followed by sodium bicarbonate and nutrient broth. Among the paired components added, sodium bicarbonate + ammonium chloride had the most significant effect, followed by sodium bicarbonate + nutrient broth and ammonium chloride + nutrient broth. The strength of bio-cemented sand cured with compound nutrient solution containing five components could reach 3.43 MPa, which was 1.92 times higher than the strength of the basic nutrient solution. As shown by the SEM image, the calcium carbonate precipitation in the solidified sand was distributed in the clearance of sand particles, effectively bonding the sand particles. The calcium carbonate obtained by the composition of the compound nutrient solution precipitated the sand particles, and some of the sand particles were wrapped. Moreover, the amount of precipitation was evidently greater than that of the basic nutrient solution. Compared with the basic nutrient solution, the compound nutrient solution effectively reduced the apparent porosity and average pore size of the sand. Thus, the curing effect of the compound nutrient solution was better than that of the basic nutrient solution.

Polymicrobial synergy stimulates Porphyromonas gingivalis survival and gingipain expression in a multi-species subgingival community

Background Dysbiosis in subgingival microbial communities, resulting from increased inflammatory transudate from the gingival tissues, is an important factor in initiation and development of periodontitis. Dysbiotic communities are characterized by increased numbers of bacteria that exploit the serum-like transudate for nutrients, giving rise to a proteolytic community phenotype. Here we investigate the contribution of interactions between members of a sub-gingival community to survival and development of virulence in a serum environment—modelling that in the subgingival pocket. Methods Growth and proteolytic activity of three Porphyromonas gingivalis strains in nutrient broth or a serum environment were assessed using A600 and a fluorescent protease substrate, respectively. Adherence of P. gingivalis strains to serum-coated surfaces was studied with confocal microscopy and 2D-gel electrophoresis of bacterial supernatants used to investigate extracellular proteins. A model multi-species sub-gingival community containing Fusobacterium nucleatum, Streptococcus constellatus, Parvimonas micra with wild type or isogenic mutants of P. gingivalis was then created and growth and proteolytic activity in serum assessed as above. Community composition over time was monitored using culture techniques and qPCR. Results The P. gingivalis strains showed different growth rates in nutrient broth related to the level of proteolytic activity (largely gingipains) in the cultures. Despite being able to adhere to serum-coated surfaces, none of the strains was able to grow alone in a serum environment. Together in the subgingival consortium however, all the included species were able to grow in the serum environment and the community adopted a proteolytic phenotype. Inclusion of P. gingivalis strains lacking gingipains in the consortium revealed that community growth was facilitated by Rgp gingipain from P. gingivalis. Conclusions In the multi-species consortium, growth was facilitated by the wild-type and Rgp-expressing strains of P. gingivalis, suggesting that Rgp is involved in delivery of nutrients to the whole community through degradation of complex protein substrates in serum. Whereas they are constitutively expressed by P. gingivalis in nutrient broth, gingipain expression in the model periodontal pocket environment (serum) appeared to be orchestrated through signaling to P. gingivalis from other members of the community, a phenomenon which then promoted growth of the whole community.

Pembentukan Biofilm Pseudomonas aeruginosa pada Beberapa Media Cair

Pseudomonas aeruginosa merupakan bakteri Gram negatif berbentuk batang bersifat patogen oportunistik yang menjadi penyebab utama infeksi nosokomial dan mampu membentuk biofilm pada media pertumbuhan, biofilm sering mengakibatkan pengobatan penyakit infeksi menjadi lebih sulit. Media pertumbuhan bakteri ada beberapa jenis, komposisi dan merek. Tujuan penelitian ini adalah untuk mengetahui kemampuan P. aeruginosa dalam membentuk biofilm pada beberapa media biakan cair. P. aeruginosa diisolasi dari sampel klinis dari rumah sakit, media cair yang digunakan adalah nutrien broth, laktosa broth, brain-heart infusion (BHI), luria bertani broth, dan tripticase soy broth. Uji pembentukan biofilm menggunakan metode microtiter plate culture technique, kemampuan pembetukan biofilm diukur berdasarakan optical density dengan menggunakan microtiter plate reader pada panjang gelombang 570nm, dengan pewarnaan crystal violet 0,1%, setelah inkubasi 24 jam pada suhu 37oC, dengan replikat 8 kali. Hasil penelitian menunjukkan bahwa P. aeruginosa memiliki kemampuan membentuk biofilm pada nutrient broth 0,926±0,081, laktosa broth 0,521±0,041, BHI 1,283±0,031, luria bertani 1,301±0,043, dan media trypticase soy broth 1,563±0,032. Pembentukan biofilm tertinggi pada trypticase soy broth, dan terendah pada laktosa broth, sedangkan pada media BHI dan luria bertani kemampuan pembentukan biofilm yang setara. Kesimpulan penelitian ini adalah P. aeruginosa memiliki kemampuan yang berbeda dalam membentuk biofilm ketika ditumbuhkan pada media cair yang berbeda.Kata kunci : Biofilm, Pseudomonas aeruginosa, media cair

The Biotransformation and Biodecolorization of Methylene Blue by Xenobiotic Bacterium Ralstonia pickettii

The biotransformation and biodecolorization of methylene blue (MB) dye using the bacterium Ralstonia pickettii was investigated. This experiment was conducted in a nutrient broth (NB) medium after adding MB at 100 mg L–1 concentration. Approximately 98.11% of MB was decolorized after 18 h of incubation. In addition, the metabolic products detected by LC-TOF/MS were Azure A (AA), thionine, leuco-MB, and glucose-MB, which indicated the MB degradation through a reductase that attacked the heterocyclic central chromophore group present in the structure. Moreover, azure A and thionine fragments resulted from the N-demethylase enzyme that attacked the auxochrome group. Thus, this research was assumed to be the first scientific report suggesting the potential to use R. pickettii in the biodecolorization and biotransformation of dye waste, particularly MB.

APLIKASI BIOSURFAKTAN Bacillus subtilis ATCC 19659 DENGAN MEDIA PRODUKSI LIMBAH TAHU UNTUK ENHACED OIL RECOVERY

Biosurfactant as secondary metabolit produced by Bacillus subtilis. It has the ability to emulsify and reduce the surface tension. Biosurfactants produced by B. subtilis is a lipopeptide. Furthermore, biosurfactant can be utilized in microbial enhanced oil recovery (MEOR). In this research, biosurfactant of B. subtilis ATCC 19 659 were evaluated. The production use Nutrient Broth (NB) and soybean liquid waste. Application of biosurfactant in oil recovery showed that biosurfactant of NB recover 2 mL crude oil and biosurfactant of soybean liquid waste medium recover 3.67 mL.

THIẾT LẬP MẪU MÁU GIẢ ĐỊNH CHỨA VI KHUẨN STAPHYLOCOCCUS AUREUS DÙNG TRONG NGOẠI KIỂM

Mục tiêu: Thiết lập mẫu máu giả định chứa S. aureus sử dụng cho chương trình ngoại kiểm chất lượng vi sinh đạt độ đồng nhất và ổn định theo ISO 17043:2011. Phương pháp: Nghiên cứu thực nghiệm. Đánh giá tốc độ tăng trưởng của và S. aureus trong môi trường máu giả định có và không có acid boric và natriformat. Xác định nồng độ acid boric và natriformat phù hợp. Thử nghiệm sản xuất bộ mẫu máu giả định chứa cơ chất nutrient broth, máu cừu, acid boric và natrifomat theo nồng độ đã xác định. Sử dụng phép kiểm T-Student và Oneway ANOVA đánh giá tính đồng nhất, tính ổn định bộ mẫu máu giả định đã sản xuất. Kết quả: Sử dụng acid boric và natrifomat duy trì nồng độ S. aureus trong mẫu (máu cứu, nutrient broth) hiệu quả hơn so với không sử dụng. Nồng độ acid boric 8% và natriformat 4% là phù hợp với sản xuất mẫu máu giả định vi khuẩn đích là S.aureus. Bộ mẫu sản xuất chứa vi khuẩn đích S. aureus đạt tính đồng nhất với Fthực nghiệm= 0,911 < F lý thuyết =3,02, ổn định trong 17 ngày. Kết luận: Qua nghiên cứu, sử dụng acid boric- natrifomat làm chất bảo quản trong môi trường máu giả định là phù hợp. Thiết lập thành công bộ mẫu máu giả định S. aureus sử dụng cho chương trình ngoại kiểm vi sinh theo tiêu chuẩn ISO 17043:2011 đạt tính đồng nhất và tính ổn định trong 17 ngày ở 220C-300C.

Biocompatibility and radioprotection by newly characterized melanin pigment and its production from Dietzia schimae NM3 in optimized whey medium by response surface methodology

Purpose To characterize and optimize the productivity of melanin using an extremotolerant actinobacterium, Dietzia schimae NM3, for the first time. Methods An extracellular brown pigment produced by D. schimae NM3 in the nutrient broth and cheese whey medium by adding L-tyrosine. The extracted melanin was analyzed by UV-visible, HPLC, and FTIR assays. The radical scavenging activity (by DPPH) and sun protection factor (SPF) of the extracted melanin were measured. The melanin cytotoxicity was assayed by MTT and chromate biosorption was measured by atomic absorption spectroscopy. Finally, melanin production by D. schimae NM3 was optimized by response surface methodology (RSM) using Box-Behnken design in the whey medium. Result The purified melanin showed similar peak to the standard melanin (SIGMA) at 3.5 min in HPLC, and C=O bands, NH2, CH, C-N, and aromatic groups by FTIR. The radical scavenging activity (by DPPH) and SPF of the extracted melanin were obtained 188.9% and 20.22, respectively. Using MTT assay, the melanin revealed non-toxic effect on the normal human fibroblast (HFB) cell culture. The melanin yield 790 mg l−1, and tyrosinase activity 3400 U ml−1 were obtained in the medium contained whey powder [5% (w v−1)], L-tyrosine 2.5 g l−1, CuSO4 0.013 g l−1, and pH 10.5, incubated at 32 °C for 3 days. The ANOVA results indicated significant P-value, model F-value, and probability, with insignificant lack of fit. After optimization with mono-factors, the nutrient broth came up with melanin yield as 1.2 g l−1 and tyrosinase activity as 4040 U ml−1. Conclusion This is the first report of melanin production by D. schimae NM3 and this natural melanin showed valuable biological properties such as high antioxidant activity and radioprotection (SPF) and the biocompatibility to human cell line.

Effect of humate on the activity of bacterial fertilizers

The plots of experiment was control (two different efficient bacteria), humate fertilizer (250 ml) in laboratory condition. The use of bacteria and humate fertilizer showed that the beneficial bacterial cell growth and development of each version increased from control, and some of the version were highly activaties. In result, beneficial bacteria have been found to be resistant to humate fertilizer and the humic fertilizer promotes bacterial growth. Бактерийн бордооны идэвхид гуматын нөлөөг судалсан дүн Дархан-Ризо шингэн бордоон дахь ашигтай бактерийн бүрэлдэхүүнд гуматын нөлөөг илрүүлэх зорилгоор лабораторийн туршилтыг гүйцэтгэв. Судалгааны материал болгон УГТХ-ийн Хөрсний микробиологийн лабораторийн өсгөврийн санд хадгалагдаж байгаа ризобактерийн эх өсгөвөр дээр гуматын бордоог 250 мл/тн тунгаар нэмж Nutrient broth шингэн тэжээлийн орчинд ургуулж хяналттай харьцуулан спектрофотометр багажаар эсийн нягтыг тодорхойлов. Судалгааны дүнгээр ризобактерийг гуматтай хольж тэжээлийн орчинд ургууулахад эхний 48 цагийн өсөлт хөгжил гумат холиогүй хувилбартай ижил зүй тогтолоор өсч байв. Харин 72 цагийн дараа гумат холиогүй хувилбарын эсийн нягт 2.422 байсан бол гуматтай орчинд агуулагдаж байгаа бактерийн эс 4.029 нягтралтай байв. Энэ нь судалгаанд ашиглаж буй гумат ризобактерийн идэвхийг дарангуйлах үйлчилгээгүй, харин өсөлтийн эрчмийг хяналтаас 1.6 дахин нэмэгдүүлдэг болохыг тогтоов. Цаашид талбайн нөхцөлд таримлуудыг бордох технологитой хамтатган нарийвчилсан судалгааны ажлуудыг хийж гүйцэтгэх нь зүйтэй юм. Түлхүүр үг: Humate fertilizer, rhizobium biofertilizer, beneficial bacteria, spectrophotometr