Henry Y. Wang

Thermostable alkaline lipase from a newly isolated thermophilic Bacillus, strain A30-1 (ATCC 53841)

A thermophilic bacterium was isolated from a hot spring area of Yellowstone National Park. The organism grew optimally at 60–65°C and in the pH range of 6–9. It was characterized as Bacillus sp. In the presence of corn or olive oil (1.0%) as the growth substrate, this Bacillus produced an extracellular lipolytic activity (EC 3.1.1.3). The enzyme activity could be efficiently recovered by ultrafiltration of cell-free culture supernatant. The partially purified lipase preparation had an optimum temperature of 60°C, at an optimum pH of 9.5. It retained 100% of the original activity after being heated at 75°C for half an hour. The half life of the enzyme was 8 h at 75°C. The enzyme retained at least 90% of the original activity after it was incubated at 60°C for 15 h at pHs in the range of 5 to 10.5. The enzyme was active on triglycerides containing fatty acids having a carbon chain length of C16 : 0 to C22 : 0 as well as on natural fats and oils. The enzyme activity was stable to both hydrogen peroxide and alkaline protease which are detergent ingredients. The purified enzyme had an isoelectric point of 5.15 and an approximate molecular weight of 65,000.

Synthesis of state feedback laws for end-point optimization in batch processes

nature of the feedback law (static or dynamic) are completely characterized in terms of the Lie bracket structure of the system dynamics. Explicit synthesis formulae for the state feedback laws are first obtained for time-invariant systems and then extended to time-varying systems. As illustrative examples of application of the proposed methodology, we consider several end-point optimization problems in batch chemical and biochemical reactors. INTRCJDUCTJON Batch and semi-batch processes are of great importance to the chemical industry. A wide variety of specialty chemicals such as antibiotics and polymers are produced in batch reactors; they are preferred due to their ease and flexibility of operation. Batch reactors are used when there are many processing steps in the chemical process, when isolation is required for reasons of sterility or safety and when the materials involved are hard to handle.

Recovery of a foreign protein from the periplasm of Escherichia coli by chemical permeabilization

We have applied the technique of protein release by chemical permeabilization to recover a foreign protein in active form from the periplasm of a recombinant strain of Escherichia coli. The two agents used in our chemical permeabilization scheme, guanidine hydrochloride and Triton X-100, have different modes of action, allowing selectivity in protein release based on intracellular location under different treatment conditions. Specifically, treatment of E. coli C600-1 cells by guanidine alone resulted in 40-fold purification of recombinant beta-lactamase, which is periplasmically expressed in this host. Achieving such high purification in the cell disruption stage could alleviate some of the problems associated with recovery of intracellular products, such as low expression or the need to solubilize cytoplasmic inclusion bodies. Recovery of periplasmic proteins by chemical permeabilization is simpler than by osmotic shock and is less expensive than using enzymatic digestion.

Effects of extractive fermentation on butyric acid production by Clostridium acetobutylicum

SummaryThe addition of an oleyl alcohol extractant to a batch fermentation of glucose byClostridium acetobutylicum resulted in a concentration profile that was distinctly different from the non-extractive control fermentation. The concentration of butyric acid increased and subsequently decreased in the control fermentation. The concentration of butyric acid increased but did not subsequently decrease in the oleyl alcohol extractive fermentation. The production of butyric acid was found to have been prolonged into the solventogenic phase in the oleyl alcohol extractive fermentation. Butyric acid was continually replenished from glucose while it was being converted to butanol. Supplementation of exogenous acetic and butyric acids, the metabolic uncoupler carbonyl cyanide 3-chlorophenylhydrazone, or decanol to the oleyl alcohol extractive fermentation helped to reinstate the normal butyric acid concentration profile. These findings are discussed with respect to the effects of these additives on the ΔpH ofC. acetobutylicum and its importance with regard to the production of butyric acid.

Microbial utilization of aqueous co-products from hydrothermal liquefaction of microalgae Nannochloropsis oculata

Hydrothermal liquefaction of algae biomass is a promising technology for the production of sustainable biofuels, but the non-oil, aqueous co-product of the process has only been examined to a limited extent. The aqueous phase from liquefaction of the alga Nannochloropsis oculata (AqAl) was used to make growth media for model heterotrophic microorganisms Escherichia coli, Pseudomonas putida, and Saccharomyces cerevisiae. Growth rates, yields, and carbon/nitrogen/phosphorus uptake were measured. E. coli and P. putida could grow using AqAl as the sole C, N, and P source in media containing 10 vol.%-40 vol.% AqAl with the best growth occurring at 20 vol.%. S. cerevisiae could grow under these conditions only if the media were supplemented with glucose. The results indicate that in a biorefinery utilizing algae liquefaction, the aqueous co-product may be recycled via microbial cultures with significantly less dilution than previously published methods.

Dechlorination of polychlorinated biphenyl congeners by an anaerobic microbial consortium

Abstract  An anaerobic methanogenic microbial consortium, developed in a granular form, exhibited extensive dechlorination of defined polychlorinated biphenyl (PCB) congeners. A 2,3,4,5,6-pentachlorobiphenyl was dechlorinated to biphenyl via 2,3,4,6-tetrachlorobiphenyl, 2,4,6-trichlorobiphenyl, 2,4-dichlorobi-phenyl and 2-chlorobiphenyl (CB). Removal of chlorine atoms from all three positions of the biphenyl ring, i.e., ortho, meta and para, was observed during this reductive dechlorination process. Biphenyl was identified as one of the end-products of the reductive dechlorination by GC-MS. After 20 weeks, the concentrations of the dechlorination products 2,4,6-CB, 2,4-CB, 2-CB and biphenyl were 8.1, 41.2, 3.0 and 47.8 μM respectively, from an initial 105 μM 2,3,4,5,6-CB. The extent and pattern of the dechlorination were further confirmed by the dechlorination of lightly chlorinated congeners including 2-CB, 3-CB, 4-CB, 2,4-CB and 2,6-CB individually. This study indicates that the dechlorination of 2,3,4,5,6-CB to biphenyl is due to ortho, meta and para dechlorination by this anaerobic microbial consortium.

Feasibility study of repeated harvesting of menthol from biologically viable Mentha x piperata using ultrasonic extraction

To potentially replace the conventional destructive extraction process, we have shown the feasibility of devising a novel technique that uses ultrasound to nonlethally and repeatedly extract menthol from biologically viable peppermint plants (Mentha x piperita). Our results show that plants ultrasonicated for 1 h at 22 °C in a standard 40 kHz ultrasonic bath could release approximately 17.8 μg of menthol per gram of leaf tissue (2% of total product). The amount of menthol release increases with the time of treatment and is greatly affected by the temperature of the ultrasonic bath water. An increase from 2% to 12% of total product was observed when the temperature was increased from 22 °C to 39 °C. When the temperature effects were isolated, the mechanism of the product release was found to be that of cavitation. The treated plants remained viable and were ready for the subsequent ultrasound extraction after approximately 4 days of recuperation. However, the amount of product released is reduced in subsequent extractions. Scanning electron micrographs indicate that there are two mechanisms involved in extraction: (1) the diffusion of product through the cuticle of peppermint glandular trichomes and (2) the exudation of the product from broken and damaged trichomes. This study has shown the possibility of using an on‐line ultrasonic, nondestructive extraction method to continuously release intracellular plant metabolites from the plants while maintaining the plants viability.

Optimal feedback control of batch reactors with a state inequality constraint and free terminal time

Abstract In this paper we derive optimal state feedback laws for end-point optimization of a dynamic system where the final time is free and the system has a scalar inequality constraint. The existence of a singular region as well as the nature of the state feedback law (static or dynamic) is completely characterized in terms of the system dynamics. Explicit synthesis formulae for the state feedback laws are presented. Once the state feedback laws for end-point optimization have been derived, issues on how these laws can be implemented as part of a closed-loop scheme are discussed. As illustrative examples of application of the proposed methodology, several end-point optimization problems in batch chemical reactors are considered.

The application of dynamic calorimetry for monitoring growth ofSaccharomyces cerevisiae

SummaryA dynamic calorimetric technique was investigated to determine the feasibility of monitoring cell growth by thermal measurements. Theoretical analysis of growth ofSaccharomyces cerevisiae on glucose showed that the correlation depends on cellular yield values but not on ethanol formation. Experiments withS. cerevisiae on a molasses-mineral salts medium resulted in a thermal yield of 4.4 kcal/g cells, consistent with our theoretical expectations.

Degradation of Pentachlorophenol by Non-Immobilized, Immobilized and Co-Immobilized Arthrobacter Cells

Abstract Non-immobilized, immobilized and co-immobilized Arthrobacter (ATCC 33790) cells were examined for their ability to degrade PCP in a mineral medium. Non-immobilized cells could completely remove PCP from the aqueous phase and mineralize 77% of the added PCP within 135 h. Alginate-encapsulated cells mineralized 86% of the PCP with a similar profile as free cells. Use of co-immobilized cells (which co-immobilized cells and activated carbon in hydrogel capsules) resulted in rapid removal of PCP from the aqueous phase and extensive PCP mineralization.