Effect of medium type, light intensity, and photoperiod on the growth rate of microalgae Chlorococcum sp. local isolate

Microalgae are microscopic organisms that are living in a watery environment, whether in fresh or seawater. As photosynthetic organisms, microalgae are the primary oxygen producers in the water. Furthermore, microalgae have various benefits for the sustainability of human beings. Chlorococcum sp. is green microalgae found in freshwater, seawater, brackish water, or even in wastewater. Publication data on this microalga are limited, but this alga is known for its high lipid content. Previously, Chlorococcum sp. was isolated from the Ampenan Estuary of Lombok Island and grown in a liquid medium using Walne’s. The purpose of this study was to determine the optimum growth factors for the cultivation of Chlorococcum sp. The microalgae growth factors that were varied as treatments were the source of water medium used (distilled water, seawater, and saline water), the light intensity (2000, 25000, 3000, and 3500 lux), and the photoperiod (16: 8; 20:4; and 24:0 hours). Based on the research data, it is known that the type of water media is very influential on the productivity of microalgae. Where the highest growth of Chlorococcum sp. was produced in a medium containing saline water. In addition, the number of cells in the initial culture also affects the life span of microalgae. The treatment with the lowest initial cells caused the cell death phase to be extended, starting from the 11th day of culture. In conclusion, the optimal growth of Chlorococcum sp. occurred on the 5th day with a cell density of 323×104 cells/ml.

Four-dimensional hydrogel-in-hydrogel bioprinting for the spatiotemporal control of organoid and organotypic cultures

Tissue architecture is a driving force for morphogenetic processes during development as well as for several physiological and regenerative responses. Far from being a passive static environment, tissue architecture is highly dynamic. Hydrogel technology reproduces in vitro geometrical and mechanical constrains that control the three-dimensional self-organization of (3D) organoids and organ-like cultures. This control is restricted to the initial culture conditions and cannot be adapted to the dynamic morphological changes of complex 3D cultures during their developmental trajectory. Here, we developed a method that overcomes this spatiotemporal limit. Using 2P crosslinking approach, high resolution 3D hydrogel structures can be fabricated within pre-existing hydrogel with spatiotemporal (four-dimensional, 4D) control relative to ex-vivo organotypic or organoid culture. This hydrogel-in-hydrogel bioprinting approach enables to continuously instruct the self-organization of the evolving 3D organ-like cultures.

Retrospective diagnosis of lymphatic tuberculosis in frozen samples using two genetic amplification methods, Xpert® MTB/RIF ULTRA and Abbott RealTime MTB Assay

Objectives. The main objective of the present study is to assess the sensitivity and specificity of a retrospective diagnostic of lymphatic tuberculosis (LTB), testing frozen samples using gene amplification PCR methods. The secondary objective was to compare the results of two different commercial tuberculosis gene amplification methods for this purpose. Material and methods. We retrospectively studied 38 frozen samples, previously processed for mycobacterial culture between January 2014 and August 2019. The results of the previous cultures were: 21 samples positive for Mycobacterium tuberculosis complex (MTB) (5 being smear positive), 7 samples culture positive for Mycobacterium avium-intracellulare complex and 10 samples which were mycobacterial culture negative and discarded for LTB diagnosis, used as controls. The samples were processed using two gene amplification methods: Xpert® MTB/RIF Ultra (Cepheid) and Abbott RealTime MTB Assay (Abbott). Results. Compared to initial culture results the sensitivity and specificity of Xpert® MTB/RIF Ultra were 57.1% and 100% and 52.3 % and 92.5%, respectively for the Abbott RealTime MTB assay. The differences were not statiscally significant. In addition, there were no differences according to the period of freezing. Conclusions. Gene amplification of frozen samples confirmed the diagnosis of lymphatic TB in almost 60% of cases, allowing retrospective diagnosis in initially non suspected cases. Both gene amplification techniques tested were equally useful.

Next Generation Sequencing Approaches Deciphering Hidden Microbial Treasure in Soil

Soil is one of the most important and complex biological habitats on earth. As we know the microbes are important key players in every ecosystem, and biological and ecological processes. Thus, it is necessary to understand this microbial treasure to have information about their role in such processes. Initial culture dependent methods helped a lot but are insufficient to indentify all the microbial species present in the soil. It has been estimated that only ~1% of bacterial species are cultivable on culture medium and rest are still hidden in through such methods. On the other hands, soil metagenomics is a modern concept that allows us to recognize these hidden species without biasness of growing bacteria on to petri plates. In last two decades rapid improvements in modern techniques itself enhanced the human capabilities in not only identifying but also have an understanding of functional aspects of these microbes in soil. Present review describes the available culture dependent methods and emergence and improvement in modern sequencing approaches helping to explore soil microbial diversity of more detail.

Screening and Assessment of Antimicrobial Susceptibility of Periodontopathic Bacteria in Peruvian Patients with Periodontitis: A Pilot Study

Background. Severe periodontal disease is highly prevalent worldwide, affecting 20% of the population between the ages of 35 and 44 years. The etiological epidemiology in Peru is scarce, even though some studies describe a prevalence of 48.5% of periodontal disease in the general population. Periodontitis is one of the most prevalent oral diseases associated with site-specific changes in the oral microbiota and it has been associated with a socioeconomic state. This study aimed to determine the etiology and resistance profile of bacteria identified in a group of Peruvian patients with periodontal disease. Methods. Six subgingival plaque samples were collected from eight patients with severe periodontitis. Bacterial identification was carried out by an initial culture, PCR amplification, and subsequently DNA sequencing. We evaluated the antibiotic susceptibility by the disk diffusion method. Results. Variable diversity in oral microbiota was identified in each one of the eight patients. The bacterial genus most frequently found was Streptococcus spp. (15/48, 31.3%) followed by Rothia spp. (11/48, 22.9%), Actinomyces spp. (9/48, 18.8%), and Eikenella spp. (4/48, 8.3%). The most common species found was Rothia dentocariosa (8/48, 16.7%). The antimicrobial susceptibility assay varied according to the species tested; however, among all the isolates evaluated, Actinomyces naeslundii was resistant to penicillin and tetracycline; Eikenella corrodens was resistant to dicloxacillin; and Rothia dentocariosa was resistant to amoxicillin + clavulanic acid and metronidazole but also susceptible to trimethoprim-sulfamethoxazole. Conclusions. The most prevalent periodontal bacterium found in this study was Rothia dentocariosa. Specific antimicrobial therapy is required to improve the treatment outcomes of patients with periodontal disease and avoid antibiotic resistance.

Enhanced Ohmyungsamycin A Production via Adenylation Domain Engineering and Optimization of Culture Conditions

Ohmyungsamycins (OMSs) A and B are cyclic depsipeptides produced by marine Streptomyces strains, which are synthesized by a non-ribosomal peptide synthetase. Notably, OMS A exhibits more potent activity against Mycobacterium tuberculosis and human cancer cells than OMS B. The substrate promiscuous adenylation (A) domain in the second module of OMS synthetase recruits either L-Val or L-Ile to synthesize OMSs A and B, respectively. Engineering of the substrate-coding residues of this A domain increased OMS A production by 1.2-fold, coupled with a drastic decrease in OMS B production. Furthermore, the culture conditions (sea salt concentration, inoculum size, and the supply of amino acids to serve as building blocks for OMS) were optimized for OMS production in the wild-type strain. Finally, cultivation of the A2-domain-engineered strain under the optimized culture conditions resulted in up to 3.8-fold increases in OMS A yields and an 8.4-fold decrease in OMS B production compared to the wild-type strain under the initial culture conditions.

Self-Generated Hypoxia Leads to Oxidative Stress and Massive Death in Ustilago maydis Populations under Extreme Starvation and Oxygen-Limited Conditions

Ustilago maydis and Saccharomyces cerevisiae differ considerably in their response to water-transfer treatments. When stationary phase cells were transferred to pure water and incubated under limited supply of oxygen, the U. maydis cells suffered a catastrophic loss of viability while the S. cerevisiae population was virtually unaffected by the treatment. The major factor underlying the death of the U. maydis cells under those conditions was an oxygen-consuming cellular activity that generated a hypoxic environment, thereby inducing oxidative stress and accumulation of reactive oxygen species, which resulted in lethality. Importantly, a small residue of U. maydis cells that did survive was able to resume growth and repopulate up to the initial culture density when sufficient aeration was restored. The regrowth was dependent on the cellular factors (Adr1, Did4, Kel1, and Tbp1), previously identified as required for repopulation, after killing with hydrogen peroxide. Surprisingly, the survivors were also able to resume growth under apparently hypoxic conditions, indicating that these remnant cells likely switched to a fermentative mode of growth. We discuss the findings in terms of their possible relevance to the eco-evolutionary adaptation of U. maydis to risky environments.

Bacteria-induced nasal necrosis with negative cultures

A 79-year-old man with liver failure, hypertension and hyperlipidemia presented with a 1.5-month history of progressive nasal crusting and pain on the inside of the nose, advancing into a necrotic columella and philtrum. On rigid endoscopy, debris extended to middle and inferior turbinate to midway posteriorly. Initial culture swabs and CT were negative. The patient underwent endoscopic biopsy of the lesion, with histopathological findings revealing abundant acute inflammation and minute fragments of atypical squamous epithelium, favouring reactive atypia. Non-invasive fungal hyphae were identified. Bacterial cultures revealed Staphylococcus epidermidis, Corynebacterium accolens, Curvularia species and Pseudomonas putida. A current literature search failed to find other published cases of P. putida nasal infections. P. putida is generally difficult to isolate on swab culture as the surrounding tissue is necrosed; this case highlights the importance of reconsidering bacterial infection and obtaining a tissue biopsy in the case of non-healing necrotic-appearing tissue with negative culture swab and CT without evidence of mass.

In vitro propagation of popular banana cultivar (Musa spp. Cv. Patakpura)

The present experiment was conducted to optimize protocols for in vitro propagation of banana (Musa sp.) cv. ‘Patakpura’ (AAB), supplemented with different growth regulators. Shoot tips obtained from sword suckers were cultured aseptically on MS medium supplemented with different concentrations of cytokinins like 6-Benzylaminopurine (BAP) and Kinetin (KN) for multiplication of shootsand auxins such as indole acetic acid (IAA) and naphthalene acetic acid (NAA) for induction of roots. The best result from the initial culture was obtained from MS medium supplimented with 4 mg/l BAP + 0.5 mg/l IAA. The highest shoot fresh weight, shoot length and number of shoots per explant were recorded from MS medium supplemented with 4 mg/l BAP + 0.5 mg/l IAA + 0.25 mg/l NAA. Therefore, the MS medium supplemented with 4 mg/l BAP + 0.5 mg/l IAA + 0.25 mg/l NAA was found to be most effective and productive combination for shoot multiplication and proliferation of the culture in vitro. IAA at a concentration of 1 mg/l was found to be most suitable for rooting of the shoots. Bangladesh J. Agril. Res. 44(4): 641-648, December 2019

High Burden of Staphylococcus aureus Among Native American Individuals on the White Mountain Apache Tribal Lands

Background This study was done to determine the burden of invasive Staphylococcus aureus on the White Mountain Apache Tribal lands. Methods Active population and laboratory-based surveillance for invasive S aureus infections was conducted from May 2016 to April 2018. A case was defined as a Native American individual living on or around the White Mountain Apache Tribal lands with S aureus isolated from a normally sterile body site. Results Fifty-three cases were identified. Most cases were adults (90.6%) and had ≥1 underlying medical condition (86.8%), the most common of which were diabetes (49.1%) and obesity (41.5%). A total of 26.4% cases were categorized as community acquired. Most infections were methicillin-resistant (75.5%). A total of 7.5% of cases required amputation, and 7.7% of cases died within 30 days of initial culture. The incidence of invasive S aureus was 156.3 per 100 000 persons. The age-adjusted incidence of invasive methicillin-resistant S aureus was 138.2 per 100 000 persons. Conclusions This community has a disproportionately high burden of invasive methicillin-resistant S aureus compared with the general US population. Interventions are urgently needed to reduce the morbidity and mortality associated with these infections.