Novel endolysin LysMP for control of Limosilactobacillus fermentum contamination in small-scale corn mash fermentation

BACKGROUND

Traditional bioethanol fermentation industries are not operated under strict sterile conditions and are prone to microbial contamination. Lactic acid bacteria (LAB) are often pervasive in fermentation tanks, competing for nutrients and producing inhibitory acids that have a negative impact on ethanol-producing yeast, resulting in decreased yields and stuck fermentations. Antibiotics are frequently used to combat contamination, but antibiotic stewardship has resulted in a shift to alternative antimicrobials.

RESULTS

We demonstrate that endolysin LysMP, a bacteriophage-encoded peptidoglycan hydrolase, is an effective method for controlling growth of LAB. The LysMP gene was synthesized based on the prophage sequence in the genome of Limosilactobacillus fermentum KGL7. Analysis of the recombinant enzyme expressed in E. coli and purified by immobilized metal chelate affinity chromatography (IMAC) showed an optimal lysis activity against various LAB species at pH 6, with stability from pH 4 to 8 and from 20 to 40 °C up to 48 h. Moreover, it retains more than 80% of its activity at 10% ethanol (v/v) for up to 48 h. When LysMP was added at 250 µg/mL to yeast corn mash fermentations containing L. fermentum, it reduced bacterial load by at least 4-log fold compared to the untreated controls and prevented stuck fermentation. In comparison, untreated controls with contamination increased from an initial bacterial load of 1.50 × 107 CFU/mL to 2.25 × 109 CFU/mL and 1.89 × 109 CFU/mL after 24 h and 48 h, respectively. Glucose in the treated samples was fully utilized, while untreated controls with contamination had more than 4% (w/v) remaining at 48 h. Furthermore, there was at least a fivefold reduction in lactic acid (0.085 M untreated contamination controls compared to 0.016 M treated), and a fourfold reduction in acetic acid (0.027 M untreated contamination controls vs. 0.007 M treated), when LysMP was used to treat contaminated corn mash fermentations. Most importantly, final ethanol yields increased from 6.3% (w/v) in untreated contamination samples to 9.3% (w/v) in treated contamination samples, an approximate 50% increase to levels comparable to uncontaminated controls 9.3% (w/v).

CONCLUSION

LysMP could be a good alternative to replace antibiotics for mitigation of LAB contamination in biofuel refineries.

Saccharomyces cerevisiae surface display of endolysin LysKB317 for control of bacterial contamination in corn ethanol fermentations

Control of bacterial contamination in bioethanol fermentation facilities has traditionally relied on chemical-based products such as hop acids and use of antibiotics. Recent emphasis on antibiotic stewardship has prompted new research into the development of alternative approaches to microbial remediation strategies. We recently described a recombinant peptidoglycan hydrolase, endolysin LysKB317, which inhibited Limosilactobacillus fermentum strains in corn mash fermentation. Here, Saccharomyces cerevisiae EBY100 was used to anchor recombinant LysKB317 using cell surface display with the a-agglutinin proteins Aga1p–Aga2p. Immunostaining and confocal fluorescence were used for localization of the extracellular interface of the cells. Yeast surface-expressed endolysin demonstrated an 83.8% decrease in bacterial cell counts compared to a 9.5% decrease in control yeast. Recombinant S. cerevisiae expressing LysKB317 used for small-scale corn mash fermentation, when infected with L. fermentum, could proactively control bacterial infection for 72 h with at least 1-log fold reduction. Analysis of fermentation products showed improved ethanol concentrations from 3.4% to at least 5.9% compared to the infection-only control and reduced levels of lactic and acetic acid from 34.7 mM to 13.8 mM and 25.5 mM to 18.1 mM, respectively. In an optimized yeast surface display system, proactive treatment of bacterial contaminants by endolysin LysKB317 can improve fermentation efficiency in the presence of L. fermentum contamination.

New strategy for liquefying corn stover pellets

The movement of solid material into and between unit operations within a biorefinery is a bottleneck in reaching design capacity, with formation of biomass slurries needed to introduce feedstock. Corn stover slurries have been achieved from dilute acid, pretreated materials resulting in slurry concentrations of up to about 150 g/L, above which flowability is compromised. We report a new strategy to liquefy corn stover at higher solids concentration (300 g/L) by initially cooking it with the enzyme mimetic maleic acid at 40 mM and 150 °C. This is followed by 6 h of enzymatic modification at 1 FPU (2.2 mg protein)/g solids, resulting in a yield stress of 171 Pa after 6 h and 58 Pa in 48 h compared to 6806 Pa for untreated stover. Mimetic treatment of corn stover pellets minimizes the inhibitory effect of xylo-oligomers on hydrolytic enzymes. This strategy allows for the delivery of solid lignocellulosic slurry into a pretreatment reactor by pumping, improving operability of a biorefinery.

Clinical assessment of acellular dermal matrix (AlloDerm©) as an option in the replacement of the temporomandibular joint disc: A pilot study

BACKGROUND

There is limited data available in the literature describing the utility of acellular dermal matrix (AlloDerm©) in the replacement of the temporomandibular joint disc. Few reports of clinicians using implantable AlloDerm to replace the disc do exist, however, this has been described for reconstruction after surgical resection of the entire temporomandibular joint complex to treat pathology, as opposed to isolated articular disc disorders. Moreover, there is a lack of description in the literature regarding associated perioperative outcomes after such a procedure. We sought to assess the immediate perioperative outcomes in the form of a pilot study, to determine whether this technique warrants further investigation in the form of prospective clinical studies.

METHODS

The study team conducted a retrospective review of medical records for patients who underwent temporomandibular joint discectomy and replacement with AlloDerm© at a single tertiary care center, from 2011 to 2016. Perioperative outcomes of interest including pain levels and range of motion were recorded and descriptive statistics were utilized for statistical analysis.

RESULTS

15 patients met the inclusion criteria, of which 87% were females and 13% males. The mean age was 47.27±15.93 years. Preoperatively, 74% of the patients reported severe pain (VAS scores of 7-10); in contrast, 73% of the patients reported only mild pain (VAS scores of 1-3) during the postoperative visits, suggesting an overall reduction in pain intensity. Range of motion also improved from an average of 27.73±13.04mm, to an average of 38.60±6.08mm (P<0.01).

CONCLUSIONS

Based on our preliminary data, patients with advanced TMJ articular disc disorders showed clinical improvement from discectomy and replacement with acellular dermal matrix (AlloDerm©). Further longitudinal studies evaluating long-term outcomes need to be conducted to validate this technique, in the form of larger sample sizes with a control group, as well as radiographic assessment of long-term clinical outcomes.

Comparison of esophagectomy with and without thoracotomy in a low-resource tertiary care center in a developing country

Esophageal cancer surgery is traditionally performed by a number of open surgical approaches. Open approaches require thoracotomy and laparotomy. Developments in instrumentation and optics have allowed the use of minimally invasive approaches to esophageal cancer, which had been traditionally managed by open operation. Minimally invasive surgery (MIS) avoids thoracotomy and laparotomy and results in quicker return to normal functions and less morbidity. In this prospective study, we compared the immediate surgical and oncologic outcomes of patients who have undergone MIS with those who have had open surgery. From November 1, 2003 to March 30, 2006, 62 cases of carcinoma esophagus were operated in Surgical unit 3 (MIS unit) in the institute. Out of the 62 patients, 34 (54.8%) underwent minimally invasive esophagectomy (MIE), and the remaining 28 patients (45.2%) underwent open surgery. Both operations were done by the same team of surgeons. The groups were compared in terms of perioperative outcomes, morbidity, mortality, and adequacy of oncologic excision. The average duration for MIS was 312.35 min (60-480 min), which was more than that of open group surgery whose average duration was 261.96 min (60-360 min). This difference was found to be not significant (P < 0.110). The average blood loss was 275.74 mL (200-500 mL) in minimally invasive group compared with 312.50 (200-500 mL) in open group (P-value 0.33). Four patients (11.76%) in MIS group had been converted to open surgery. Average duration of hospitalization was 11.9 (4-24) days in MIS group compared with 12.19 (5-24) days in open group (P-value 0.282). Nine (26.47%) patients in MIS group had developed major or minor morbidity. Similarly, eight (28.57%) patients in open group had morbidity. One patient each expired in each group. The morbidity and mortality rates were not statistically significant. There were four leaks (11.76%) in MIS group and three leaks (10.71%) in open group (P-value 0.85). Regarding the extent of nodal clearance, an average number of 9.5 (0-19) nodes were removed in MIS group compared with an average of 7.26 (0-12) nodes in open group (P-value 0.05). Better visibility and magnification enabled more number of lymph nodes to be removed in MIS group. MIE is oncologically safe compared with open surgery. It has almost similar postoperative course, morbidity pattern, and duration of hospital stay as open surgery. Increased duration of procedure compared with open surgery is a disadvantage of MIS, especially in the early part of learning curve.

Hypercalcemia induced by parathyroid hormone-related peptide after treatment of squamous cell carcinoma of oral cavity

Squamous cell carcinoma of the head and neck is a rare cause of humoral hypercalcemia of malignancy. This paraneoplastic syndrome is usually one of the presenting symptoms of the disease. We report a case of squamous cell carcinoma of the oral cavity that presumably elaborated parathyroid hormone-related peptide (PTH-rP) and caused hypercalcemia only after radiotherapy and chemotherapy.

Property loss estimation for wind and earthquake perils

This article describes the development of a generic loss assessment methodology, which is applicable to earthquake and windstorm perils worldwide. The latest information regarding hazard estimation is first integrated with the parameters that best describe the intensity of the action of both windstorms and earthquakes on building structures, for events with defined average return periods or recurrence intervals. The subsequent evaluation of building vulnerability (damageability) under the action of both earthquake and windstorm loadings utilizes information on damage and loss from past events, along with an assessment of the key building properties (including age and quality of design and construction), to assess information about the ability of buildings to withstand such loadings and hence to assign a building type to the particular risk or portfolio of risks. This predicted damage information is then translated into risk-specific mathematical vulnerability functions, which enable numerical evaluation of the probability of building damage arising at various defined levels. By assigning cost factors to the defined damage levels, the associated computation of total loss at a given level of hazard may be achieved. This developed methodology is universal in the sense that it may be applied successfully to buildings situated in a variety of earthquake and windstorm environments, ranging from very low to extreme levels of hazard. As a loss prediction tool, it enables accurate estimation of losses from potential scenario events linked to defined return periods and, hence, can greatly assist risk assessment and planning.

Nasopharyngeal presentation of renal cell carcinoma

In this case report, we present a 50-year- old woman, who presented with severe headache as her only presenting clinical symptom due to nasopharyngeal mass. Histo-pathological evaluation of the biopsy from nasopharyngeal mass revealed clear cell carcinoma. On further evaluation, an asymptomatic mass was detected in the left kidney. The metastatic lesion was treated with palliative radiotherapy. A search of the literature revealed no reports of such unusual metastasis in the nasopharynx from a primary carcinoma of the renal origin.

Branchiogenic carcinoma--a case for radiation induced carcinogenesis

From the time the first case of bronchial cleft carcinoma was reported over a century ago, very few cases have been reported which prove to be a cancer of primary branchial origin, while many metastatic cystic squamous cell carcinomas in the neck have been wrongly categorized as branchial carcinoma. Here, we describe a case of primary branchiogenic carcinoma in a 53 year old Libyan female showing a transformation of a benign epithelium into a malignant type. We further report that this transformation is perhaps brought about by an irregular radiotherapy to the head and neck region.

Sequential respiratory, psychologic, and immunologic studies in relation to methyl isocyanate exposure over two years with model development

Of 113 methyl isocyanate (MIC)-exposed subjects studied initially at Bhopal, India, 79, 56, 68, and 87 were followed with clinical, lung function, radiographic, and immunologic tests at 3, 6, 12, 18, and 24 months. Though our cohort consisted of subjects at all ages showing a varied severity of initial illness, fewer females and young subjects were seen. Initially all had eye problems, but dominant symptoms were exertional dyspnea, cough, chest pain, sputum, and muscle weakness. A large number showed persistent depression mixed with anxiety, with disturbances of personality parameters. The early radiographic changes were lung edema, overinflation, enlarged heart, pleural scars, and consolidation. The persistent changes seen were interstitial deposits. Lung functions showed mainly restrictive changes with small airway obstruction; there was impairment of oxygen exchange. Oxygen exchange improved at 3-6 months, and spirometry improved at 12 months, only to decline later. The expiratory flow rates pertaining to large and medium airway function improved, but those for small airways remained low. There were changes of alveolitis in bronchoalveolar lavage fluid on fiber optic bronchoscopy, and in 11 cases positive MIC-specific antibodies to IgM, IgG, and IgE were demonstrated. On follow up, only 48% of the subjects were clinically stable, while 50% showed fluctuations. Thirty-two percent of the subjects had lung function fluctuations. Detailed sequential behavior over 2-4 years was predicted for dyspnea, forced vital capacity, maximum expiratory flow rate (0.25-0.75), peak expiratory flow rate, VO2, and depression score. A model for clinical behavior explained a total variance of 52.4% by using the factors of cough, PCO2 and X-ray zones in addition to above five parameters. The behavior of the railway colony group (1640 patients) revealed a similar pattern of illness. When this observed pattern of changes was transferred to the affected Bhopal city sections (with an equitable age-sex distribution), our model results were again validated. Thus the picture of MIC-induced disease seems similar despite the differences for age-sex and initial severity of illness in our cohort and in the population of Bhopal city as predicted by our model.

Comparative study of amoxycillin and amoxycillin/clavulanic acid in lower respiratory infections

A comparison of oral amoxycillin (500 mg tds) with amoxycillin/clavulanic acid (Augmentin; 750 mg tds) for 7 to 10 days was completed in 76 patients with lower respiratory infection. In another 9 patients, intravenous Augmentin alone was administered (1.2 g 8 hourly) for 3 days followed by oral doses as above for 7 days. In 50 (59%) patients the underlying chronic lung disease was bronchiectasis. Clinical improvement (1 + or more) was seen in 66% with amoxycillin, 60% with oral Augmentin and 56% with IV Augmentin. For radiographic improvement the respective figures were 47, 53 and 44 per cent. Bacteriologically, elimination was seen in 8% with amoxycillin and 45% with Augmentin (P less than 0.01), while partial success was seen in 16 and 24 per cent respectively. While for gram positive organisms, both drugs were similar in efficacy, for gram negative strains the overall success was 27% with amoxycillin and 67% with Augmentin. The main organisms isolated were Str pneumoniae (12), Klebsiella (41), Pseudomonas (21), E coli (9), Haemophilus (7) and Staph aureus (6). For bacteriologic sensitivity and consequent success, Augmentin may be superior in respiratory infections.